133,99 €
Mehr erfahren.
- Herausgeber: Wiley-VCH GmbH
- Kategorie: Wissenschaft und neue Technologien
- Sprache: Englisch
>Collagen-Derived Materials
Comprehensive Resource for Current Ideas and Strategies for the Synthesis and Characterization of Advanced Collagen-Derived Materials
This book presents and summarizes new synthetic strategies and multi-functional applications of collagen-derived materials in electrochemical energy storage and conversion. Through easily-comprehensible illustrations and images, the book presents basic knowledge for collagen-derived materials (including gelatin and collagen-derived carbons) and their typical synthesis and applications, thus enabling students and new researchers to obtain a thorough understanding of different materials and corresponding application areas.
This book also serves as an important reference book for scientists and engineers in different research fields. It presents the up-to-date ideas and strategies for the synthesis and characterization of advanced collagen-derived materials, as well as multi-functional applications (especially in energy-related areas). Sample topics covered within the book include:
- Structural compositions, properties, and extraction of collagen and gelatin
- Precursors, structural compositions, and synthesis of collagen-derived carbons
- Applications of collagen-derived materials in electrochemical energy storage and conversion
- Applications of collagen-derived materials as electrode and supporting materials in the electrochemical energy storage and conversion systems, including capacitors, batteries, and electrocatalysts
- Challenges and opportunities for the design and synthesis of different collagen-derived materials
For electrochemists, materials scientists, chemical engineers and students in related programs of study who are interested in the topic of collagen-derived materials, Collagen-Derived Materials: Synthesis and Applications in Electrochemical Energy Storage and Conversion serves as an important resource for gaining a holistic understanding of the field and learning about the state of the art based on promising energy-related applications.
Sie lesen das E-Book in den Legimi-Apps auf:
Seitenzahl: 518
Veröffentlichungsjahr: 2022
Ähnliche
Table of Contents
Cover
Title Page
Copyright
Preface
1 Introduction
1.1 Electrochemical Energy Storage and Conversion
1.2 Materials for Electrochemical Energy Storage and Conversion
1.3 Collagen‐Derived Materials for Electrochemical Energy Storage and Conversion
References
2 Collagen
2.1 History of Collagen
2.2 Structure and Composition of Collagen
2.3 Classification, Function, and Distribution of Collagen
References
3 Synthesis and Applications of Collagen
3.1 Biosynthesis of Collagen
3.2 Extraction of Collagen
3.3 Applications of Collagen
References
4 Gelatin
4.1 History of Gelatin
4.2 Structures and Compositions
4.3 Properties and Characterization
References
5 Synthesis of Gelatin
5.1 Raw Materials
5.2 Extraction
5.3 Modification
References
6 Applications of Gelatin in Electrochemical Energy Storage and Conversion
6.1 As Binders for Battery Electrodes
6.2 As Modifying Agents for Battery Electrodes
6.3 As Modifying Agents for Battery Separators
6.4 As Electrodeposition Additives for Electrode Preparation
6.5 As Hydrogel Electrolytes for Batteries
6.6 Other Applications in Electrochemical Energy and Conversion
References
7 Collagen‐Derived Carbons
7.1 History of Collagen‐Derived Carbons
7.2 Carbonization Mechanism of Collagen‐Derived Carbons
7.3 Structures and Compositions of Collagen‐Derived Carbons
References
8 Synthesis of Collagen‐Derived Carbons
8.1 Conventional Preparation Methods
8.2 Nature‐Inspired Methods
References
9 Applications of Collagen‐Derived Carbons in Electrochemical Energy Storage and Conversion
9.1 As Electrode Materials for Supercapacitors
9.2 As Electrode Materials for Hybrid Capacitors
9.3 As Anode Materials for Alkali‐Ion Batteries
9.4 As Anode Modifiers for Alkali‐Ion Batteries
9.5 As Modifying Agents for Li–S Batteries
9.6 As Metal‐Free Electrocatalysts
9.7 As Support Materials for Hybrid Electrocatalysts
9.8 As Support Materials for Metal–Nitrogen–Carbon Electrocatalysts
References
10 Challenges and Opportunities
10.1 Principles for Material Design
10.2 Strategies for Material Synthesis
10.3 Diversities for Material Applications
10.4 Inspirations for Other Materials and Their Applications
References
Index
Wiley End User License Agreement
List of Tables
Chapter 1
Table 1.1 Biomass‐derived materials for electrochemical energy storage and c...
Chapter 2
Table 2.1 Chains of collagen family.
Table 2.2 The structures of the different collagen types.
Chapter 4
Table 4.1 Component of gelatin [18].
Table 4.2 Amino‐acid composition of collagen and four different gelatin‐amin...
Table 4.3 Hydrophilic and hydrophobic amino acids in gelatin [8].
Table 4.4 Gel strength and melting point of various fish gelatins [36].
Chapter 5
Table 5.1 Raw material conditioning [1].
Table 5.2 Raman peaks position of gelatin extracted from bovine bone powder ...
Table 5.3 Typical particle sizes of gelatin blends in the market [1].
Table 5.4 Overview of possible chemical modifications [1].
Chapter 7
Table 7.1 Elemental analysis [3].
Table 7.2 Pore structure of collagen‐derived PC.
Table 7.3 Porosity parameters, nitrogen, and content of the gelatin‐based ca...
Table 7.4 Specific surface area (SSA) and total pore volume (
V
pore
) of sampl...
Table 7.5 Pore structural parameters.
Table 7.6 Deconvolution results (at%) for the XPS core‐level spectra of N 1s...
Table 7.7 Elementary composition evaluated from elemental analysis and relat...
Chapter 10
Table 10.1 Principle and characteristics of different characterization techn...
List of Illustrations
Chapter 1
Figure 1.1 Schematics of typical systems for electrochemical energy storage ...
Figure 1.2 Illustration of the charging/discharging process within a lithium...
Figure 1.3 Schematic of energy storage mechanisms of (a) an EDLC and (b) a p...
Figure 1.4 Schematic of a PEMFC.
Figure 1.5 Schematic of a water electrolyzer.
Figure 1.6 Different types of anode materials for lithium‐ion batteries.
Figure 1.7 Progress in the development of ORR electrochemical catalysts.
Figure 1.8 Schematic diagram showing the structure and properties of biomass...
Figure 1.9 Overview of the hierarchical structure for collagen triple helix....
Chapter 2
Figure 2.1 Collagen triple‐helix structure.
Figure 2.2 Projection of the triple‐helical structure of collagen. (a) Indic...
Figure 2.3 Collagen triple‐helix structure in which glycine occupies positio...
Figure 2.4 Illustrations of the structural features for collagen chains. (a)...
Figure 2.5 (a) Diagrammatic representation of entire α(II) chain. (b) The am...
Figure 2.6 Schematic diagram of type IV collagen and chains in the basement ...
Figure 2.7 Schematic diagram of type VI collagen and chains.
Figure 2.8 Schematic diagram of type VII collagen and chains in the dermis....
Figure 2.9 Molecular forms of the fiber‐forming collagens. (a) A procollagen...
Figure 2.10 Schematic diagram of type I procollagen processing.
Figure 2.11 Aggregate structures formed by (a) the fiber‐forming collagens (...
Figure 2.12 Assembly of the collagen IV molecules in the macromolecular netw...
Chapter 3
Figure 3.1 Posttranslational modifications and assembly of the procollagen m...
Figure 3.2 Biosynthesis and processing of collagen.
Figure 3.3 The schematic image of fibrillization according to the additives....
Figure 3.4 (a) Dialyzed and (b) lyophilized collagens extracted by the acid ...
Figure 3.5 Combined effect of acid concentration, hydrolysis time, and hydro...
Figure 3.6 Protein patterns of collagens from fish skin extracted with aid o...
Figure 3.7 An illustrative image demonstrating a proposed skin wound‐healing...
Figure 3.8 Construction of tissue‐engineered tendons (A–C) and macroscopic a...
Figure 3.9 (a) Photographs of different films prepared from CG, CH, SPI, CG/...
Figure 3.10 Visual appearance of (a) grouper fish and (b) grouper swim bladd...
Chapter 4
Figure 4.1 Capsule and tablet applications of gelatin.
Figure 4.2 Food applications of gelatin.
Figure 4.3 The evolution of gelatin.
Figure 4.4 Molecular structure of gelatin.
Figure 4.5 Amino‐acid composition of gelatin. Glycine is the most abundant; ...
Figure 4.6 Gelatin is not a monodisperse protein but rather consists of a mi...
Figure 4.7 The
Fourier transform infrared spectroscopy
(
FT‐IR
) spectra...
Figure 4.8 Chemical structures of the most important amino acids of collagen...
Figure 4.9 Microstructures of European eel gelatin gel.
Figure 4.10 Images of
scanning electron microscopy
(
SEM
) of giant squid skin...
Figure 4.11 Charge distribution pattern of type A and B gelatins in aqueous ...
Figure 4.12 Stable emulsion with gelatin (a) and “broken” emulsion without g...
Figure 4.13 The thermoreversible gelling process for gelatin.
Figure 4.14 Model of gel formation (from sol to gel upon cooling).
Figure 4.15 The temperature sweep test of commercial gelatin. Cooling (a) an...
Figure 4.16 Schematic presentation of (a) flexible random coils of gelatin i...
Chapter 5
Figure 5.1 The central layer of the cattle hide (“split”) is an excellent so...
Figure 5.2 The raw material consumption for gelatin production in 2006, worl...
Figure 5.3 Poultry gelatin: a sustainable alternative for mammalian gelatin....
Figure 5.4 (a) A typical setup of gelatin extraction/production in the indus...
Figure 5.5 Microstructure of bovine bone collagen after different pretreatme...
Figure 5.6 (a): Raman spectrum between 700 and 3300 cm
−1
of gelatin ex...
Figure 5.7 Common gelatin extraction process from various gelatin sources....
Figure 5.8 Sterilization by direct steam injection is the most common techno...
Figure 5.9 Structure of cross‐linked gelatins with various reagents. *Can be...
Figure 5.10 Typical reaction mechanisms of common chemical modification of g...
Figure 5.11 Applications of gelatins (pictures taken randomly from google im...
Chapter 6
Figure 6.1 (a) Working mechanism of a Li–S battery involving formation of li...
Figure 6.2 The polysulfide‐trapping mechanisms of batteries with GPC binder....
Figure 6.3 (a) The rate capacity of GPC‐based battery and (b) corresponding ...
Figure 6.4 Schematic illustrations of the preparation and binding mechanisms...
Figure 6.5 Graphical illustration of SEI formation processes on (a) Li, (b) ...
Figure 6.6 Graphical illustration of gelatin‐based artificial SEI's effects:...
Figure 6.7 Li–Cu cells: (a, c) Coulombic efficiency at various current densi...
Figure 6.8 Graphical illustration of the experiment process.
Figure 6.9 Cycling stabilities of two cells at (a) 0.2 C and (b) 0.5 C.
Figure 6.10 (a) Voltage–capacity profiles of cell with C/GM cathode at 0.5 C...
Figure 6.11 Graphic illustration of separator construction for LIBs with hig...
Figure 6.12 Graphic illustration of thin carbon layer–modified separator obt...
Figure 6.13 Voltage curves of the Li–S cells with (a) pristine separator and...
Figure 6.14 Fabrication of the protein‐based Janus nanofabric and its effect...
Figure 6.15 Schematic illustration of the possible ion‐transport situation f...
Figure 6.16 Morphological observation of postmortem Li metal. (a–d) Morpholo...
Figure 6.17 Electrodeposition of Sn from different solutions with varying ti...
Figure 6.18 The mechanisms of the Zn deposits growth on the Zn surface in th...
Figure 6.19 The surface and cross section morphology of cathode layer and th...
Figure 6.20 The schematic illustration of the molecular conformation of (a) ...
Figure 6.21 Schematic illustration of synthesizing process and structures fo...
Figure 6.22 (a) The impedance plots of ionogels with different contents of g...
Figure 6.23 Schematic representation of the synthesis route to the HPE. The ...
Figure 6.24 Electrochemical performance of the rechargeable solid‐state Zn‐i...
Figure 6.25 (a) Schematic representation of the overall process to make GAME...
Figure 6.26 Cryogenic‐cross‐link process for fabricating the Ba(OH)
2
@gelatin...
Figure 6.27 The morphology of the precursor at different hydrothermal reacti...
Figure 6.28 Self‐assembly process for large‐area ultrathin 2D TMCs. (a) Tran...
Chapter 7
Figure 7.1 (a) TG curves of gelatin. (b)TG–FTIR patterns of gelatin heated i...
Figure 7.2 (a) XRD patterns and (b) Raman spectra of samples pyrolyzed at di...
Figure 7.3 Schematic illustration of the carbonization mechanism for gelatin...
Figure 7.4 Comparison of the structure–property relationship of carbon struc...
Figure 7.5 (a) Schematic diagram of CQD synthesis, (b) TEM images of CQDs. I...
Figure 7.6 XPS spectra of CQDs: (a) Full survey spectrum, (b) C 1s spectrum,...
Figure 7.7 (a) Schematic of the synthesis process of photoluminescent CQDs b...
Figure 7.8 (a) XPS survey spectrum, (b) the high‐resolution C 1s peaks and t...
Figure 7.9 SEM images of the carbon fibers obtained from different precursor...
Figure 7.10 (a) Schematic illustration of sustainable synthesis and assembly...
Figure 7.11 (a) Optical image of a freestanding B/N‐CS film; (b) a flexible ...
Figure 7.12 Illustration of the synthetic process of P‐NCNS electrocatalyst....
Figure 7.13 Representative SEM and TEM images of (a, b) NCNS, (d, e) H‐NCNS,...
Figure 7.14 Schematic of the synthesis process of porous carbon frameworks f...
Figure 7.15 XRD patterns (a) and Raman spectra (b) of the NPCs. (c) Nitrogen...
Figure 7.16 (a) Photograph of LWCAs on daisy; (b) SEM image of LWs; (c, d) S...
Figure 7.17 FESEM (a), TEM (b) and HR‐TEM (c) images of GAC4; nitrogen (77 K...
Figure 7.18 Schematic illustration of the preparation process of carbon foam...
Figure 7.19 SEM images of (a) CFs‐450, (b) CF‐550, (c) CFs‐700 and (d) CFs‐7...
Figure 7.20 SEM images of (a) N,O‐HPC‐650, (b) N,O‐HPC‐750, (c) N,O‐HPC‐850,...
Figure 7.21 (a, b) SEM images, (c) AFM image, (d) TEM image of HPCNS. (e–g) ...
Figure 7.22 (a) Nitrogen adsorption–desorption isotherms and (b) plots of th...
Figure 7.23 (a) Schematic of the fabricating process for the TBC samples. Th...
Figure 7.24 (a, b) SEM images of the TBC samples. (c) TEM image of one singl...
Figure 7.25 (a) Schematic illustration of heteroatoms doped carbon; types of...
Figure 7.26 (a) XPS core‐level spectra of N 1s for CG400, CG600, CG800, and ...
Figure 7.27 (a) The schematic diagram of preparation of pigskin‐derived acti...
Figure 7.28 (a) Model of binding energy of undoped and S‐doped graphene, (b)...
Figure 7.29 Schematic illustration of the synthesis procedure of the S‐HNMC ...
Figure 7.30 Representative SEM and TEM images of (a, c) NHPC and (b, e) N,P‐...
Figure 7.31 (a) XRD patterns, (b) Raman spectra of NHPC, N‐HPC, N,P‐HPC, and...
Figure 7.32 (a) Schematic diagram for the preparation procedure of FBPC. Mor...
Figure 7.33 Characterization of FBPC. (a) XRD pattern, (b) Raman spectrum, (...
Chapter 8
Figure 8.1 Structural mechanism model of pore formation in the carbon materi...
Figure 8.2 (A) Preparation of PPL–Zn composite (above).(B) Synthesis pro...
Figure 8.3 Synthesis process of the N,P‐HPC[48].
Figure 8.4 (a, b) TEM images of N,P‐HPC. (c) Nitrogen adsorption–desorption ...
Figure 8.5 Synthesis process of S,N,P‐HPC.
Figure 8.6 (a) TG curve of the mixture of N,P‐HPC and THU. (b) The decomposi...
Figure 8.7 The synthesis process of P‐NCNS.
Figure 8.8 (a) TG curve. (b) Single‐ion current curves of co‐pyrolysis of NC...
Figure 8.9 (a) XPS survey and high‐resolution XPS spectra of (b) N 1s for NC...
Figure 8.10 (a) TEM images of CP‐T. (b) Nitrogen adsorption–desorption isoth...
Figure 8.11 (a) TGA/DSC curves and (b) TG–IR patterns of cattle bone tested ...
Figure 8.12 (a) Raman spectra, (b) XRD patterns, and (c) resistivities and e...
Figure 8.13 (a, b) SEM images, (c) TEM image, and (d) HRTEM image of HDMPC....
Figure 8.14 (a) Nitrogen adsorption–desorption isotherm (inset) and pore‐siz...
Figure 8.15 (a) Schematic illustration of the preparation of N,O‐HPC. SEM im...
Figure 8.16 (a) N
2
absorption–desorption isotherms, (b) pore‐size distributi...
Figure 8.17 SEM images of (a1, a2) NHPC–HA, (b1, b2) NHPC–KOH, and (c1, c2) ...
Figure 8.18 (a) N
2
adsorption–desorption isotherms, (b) pore‐size distributi...
Figure 8.19 (a) Nitrogen adsorption–desorption isotherms and (b) plots of th...
Figure 8.20 Schematic illustration for the preparation of hierarchically por...
Figure 8.21 (a, e) SEM images, (b, f) TEM images, (c, g) HRTEM images (inset...
Figure 8.22 (a) Nitrogen adsorption/desorption isotherms, (b) plots of the p...
Figure 8.23 Schematic illustration of the synthesis of PCNSs doped by O, N, ...
Figure 8.24 (a) SEM images of gelatin@KCs. (b) SEM, (c) TEM, and (d) AFM of ...
Figure 8.25 (a) Nitrogen adsorption–desorption isotherms, (b) plots of pore‐...
Figure 8.26 Schematic illustration of the preparation of O,N,S‐doped MPCNSs ...
Figure 8.27 (a) SEM image of gelatin@KCs and the corresponding element distr...
Figure 8.28 (a) Nitrogen adsorption–desorption isotherms (inset) and pore‐si...
Figure 8.29 Schematic illustration for the formation of (a) NOPCNS, (b) NOCB...
Figure 8.30 SEM images of (a) NOPCNS, (b) NOCB1, and (c) NOCB2. (d) TEM imag...
Figure 8.31 (a) Nitrogen adsorption–desorption isotherms, (b) pore‐size dist...
Chapter 9
Figure 9.1 (a) The mechanism of energy storage and mass transfer in heteroat...
Figure 9.2 Schematic diagram of the preparation of the oxygen‐enriched activ...
Figure 9.3 Electrochemical two‐electrode performance of the symmetric superc...
Figure 9.4 (a) The mechanism of energy storage and mass transfer in a hetero...
Figure 9.5 Electrochemical performance of HDMPC||HDMPC LIC. (a) Schematic il...
Figure 9.6 (a) Schematic illustration for the preparation of hierarchically ...
Figure 9.7 (a) The schematic illustration of the discharge process. Electroc...
Figure 9.8 (a) Schematic illustration of the charge‐storage mechanisms for t...
Figure 9.9 (a) Illustration of synthesis procedure and photograph of derived...
Figure 9.10 (a) Preparation process of the 3D‐HPCs hard‐carbon materials, (b...
Figure 9.11 (a) Schematic illustration of the synthesis of amorphous SnO
2
su...
Figure 9.12 (a) Schematic diagram of the procedure to prepare the Si@GC anod...
Figure 9.13 Electrochemical performance of the sulfur cathode with porous ca...
Figure 9.14 Electrochemical performance of the sulfur/carbon nanocomposite c...
Figure 9.15 Electrochemical performance of Li–S batteries using FBPC‐modifie...
Figure 9.16 (a) Schematic illustration of the synthetic process for the N,P‐...
Figure 9.17 (a) Schematic illustration of the synthesis process of porous ca...
Figure 9.18 (a) Schematic illustration of the synthetic process for the Pt
1
/...
Figure 9.19 (a) Schematic illustration of the synthetic process for the Co
3
O
Figure 9.20 (a) Schematic illustration of the synthetic process for the SA‐F...
Figure 9.21 Schematic representation of the synthetic process for Fe‐N‐HPC‐A...
Figure 9.22 (a) Schematic representation of the synthetic process. (b) Cycli...
Chapter 10
Figure 10.1 Schematic illustration of in situ structural characterization of...
Figure 10.2 In situ XRD and neutron scattering profiles of graphite during L...
Figure 10.3 In situ TEM study on lithiation and delithiation of a bilayered ...
Figure 10.4 In situ optical and Raman microscopy study on lithiation. (a, b)...
Figure 10.5 Multi‐scale computation methods and their applications in Li‐ion...
Figure 10.6 (a) Images of graphite particle used to extract the Li concentra...
Figure 10.7 Schematic illustration of the synthesis of P,N‐doped interconnec...
Figure 10.8 The schematic of the preparation of W‐BP nanosheets and D‐BP nan...
Figure 10.9 Schematic illustration for the preparation of the Ce
x
/TiO
2
nanof...
Guide
Cover
Table of Contents
Title Page
Copyright
Preface
Begin Reading
Index
Wiley End User License Agreement
Pages
iii
iv
ix
x
1
2
3
4
5
6
7
8
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
120
121
122
123
124
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
203
205
206
207
208
209
210
211
212
213
214
215
216
217
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
279
280
281
282
283
284
285
286
287
288
289
290
291
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
Collagen‐Derived Materials
Synthesis and Applications in Electrochemical Energy Storage and Conversion
Feng Wang, Yaqin Huang, and Jin Niu
Authors
Prof. Feng WangBeijing University of Chemical TechnologyKey Laboratory of Chemical Resource EngineeringLaboratory of Electrochemical Process and Technology for materials15 Beisanhuan East Road100029 BeijingChina
Prof. Yaqin HuangBeijing University of Chemical TechnologyKey Laboratory of Chemical Resource EngineeringLaboratory of Electrochemical Process and Technology for materials15 Beisanhuan East Road100029 BeijingChina
Associate Professor Jin NiuBeijing University of Chemical TechnologyKey Laboratory of Chemical Resource EngineeringLaboratory of Electrochemical Process and Technology for materials15 Beisanhuan East Road100029 BeijingChina
Cover Image: © halepak/Getty images
All books published by WILEY‐VCH are carefully produced. Nevertheless, authors, editors, and publisher do not warrant the information contained in these books, including this book, to be free of errors. Readers are advised to keep in mind that statements, data, illustrations, procedural details or other items may inadvertently be inaccurate.
Library of Congress Card No.: applied for
British Library Cataloguing‐in‐Publication DataA catalogue record for this book is available from the British Library.
Bibliographic information published by the Deutsche NationalbibliothekThe Deutsche Nationalbibliothek lists this publication in the Deutsche Nationalbibliografie; detailed bibliographic data are available on the Internet at <http://dnb.d-nb.de>.
© 2022 WILEY‐VCH GmbH, Boschstr. 12, 69469 Weinheim, Germany
All rights reserved (including those of translation into other languages). No part of this book may be reproduced in any form – by photoprinting, microfilm, or any other means – nor transmitted or translated into a machine language without written permission from the publishers. Registered names, trademarks, etc. used in this book, even when not specifically marked as such, are not to be considered unprotected by law.
Print ISBN: 978‐3‐527‐34962‐3ePDF ISBN: 978‐3‐527‐83450‐1ePub ISBN: 978‐3‐527‐83451‐8oBook ISBN: 978‐3‐527‐83452‐5
Preface
Global energy demand and environmental degradation have resulted in a severe crisis in the sustainable development of the international community. In this context, it is necessary to develop high‐efficiency electrochemical energy storage and conversion devices to address the challenges. The assembly of the devices needs materials (especially electrode materials) that should not only show high performance but also have sustainability and low cost.
As one kind of natural biomass, collagen exists in the connective tissues of animals, comprising 23 kinds of amino acids. As the hydrolysate of collagen, gelatin has unique water solubility, rheological property, and gel property. By virtue of rich carbon atoms and non‐carbon atoms (e.g. nitrogen, oxygen, and sulfur), collagen and gelatin can be converted into a new kind of carbon material. The collagen‐derived carbons have heteroatom doping and unique morphologies, which are derived from the natural structural compositions of the collagen‐enriched precursors. By virtue of their structural compositions and unique properties, the collagen‐derived materials (including gelatin and collagen‐derived carbons) show promising applications in electrochemical energy storage and conversion.
Our group has been devoted to collagen and collagen‐derived materials since 1997. We started from the gelatin extraction from collagen and gradually expanded the applications of collagen‐derived materials. So far, gelatin with and without modification has been used as different modifying agents for electrodes, separators, and electrolytes. Collagen‐derived carbons with different morphology structures and chemical compositions have also been used as electrodes and support materials for electrochemical energy storage and conversion. Based on the related works, we have published over 100 peer‐reviewed journal papers and authored more than 40 patents.
This book is based on our published works and also includes typical works by other researchers. It is divided into ten chapters, and written by Prof. Feng Wang, Prof. Yaqin Huang, and Prof. Jin Niu. This book covers basic knowledge of collagen and collagen‐derived materials, and their typical synthesis and applications. Moreover, it also presents the up‐to‐date ideas and strategies for the synthesis and characterization of advanced collagen‐derived materials, as well as multifunctional applications in electrochemical energy storage and conversion. Therefore, this book can not only enable students and new researchers to obtain easy understanding of these materials and their applications but also serve as an important reference book for scientists and engineers in other research fields.
I would like to thank the other group members for their assistance during the book writing, including Mengyue Liu, Yongzheng Shi, Feng Zhu, Junhui Sun, Binke Li, Na Yang, Rong Shao, Jiaxing Liu, and Weihao Song. I would also like to thank my current and former group members, as well as collaborators who have contributed to the study on collagen‐derived materials. Finally, we would like to acknowledge the financial support from the National Natural Science Foundation of China (52130206, U20A20337, 51432003, 22178016, and 52003025) and Fundamental Research Funds for the Central Universities (buctrc202024).
Beijing, China10 August 2021
Feng Wang
1Introduction
1.1 Electrochemical Energy Storage and Conversion
Electric energy plays a very important role in our daily life and industrial production. Fossil fuel, nuclear heat, and renewable energies (e.g. solar energy, wind energy, and biomass energy) all can be converted into electric energy [1]. Unfortunately, the energy‐conversion processes are always accompanied by a lot of energy loss. For instance, the conversion efficiency of nuclear heat to electric energy is only ∼30%. Moreover, the electric energy derived from renewable energies depends highly on weather, season, and territory, which cannot meet the actual demand in time. Thus, it is an urgent need to address the issue of electric energy storage and conversion.
Developing advanced energy storage and conversion technologies is critical to improving the energy utilization efficiency and expanding the energy application field. Secondary batteries, supercapacitors, water electrolyzers, and fuel cells are some of the typical electrochemical energy storage and conversion devices. Figure 1.1 shows the schematics of these electrochemical energy storage and conversion systems [2]. Electric energy can be converted into chemical energy by water electrolyzers, producing hydrogen (with a conversion efficiency of ∼70%) for further use in fuel cells. In the opposite process, fuel cells convert chemical energy into electric energy. The energy‐conversion process is reversible in secondary batteries (e.g. lithium‐ion battery). Electric energy can be converted into chemical energy in the charging process [3]. In the discharging process, the chemical energy is converted back into electric energy. The conversion speed determines the system power, while the storage capacity is relevant to the system energy. Generally, the active materials for energy conversion and storage are integrated into secondary batteries because of the internal system. Different from secondary batteries, the electrolyzer and fuel cell systems are suitable for separated converters and storage. This kind of electrochemical storage and conversion systems commonly supplies higher energy than that with integrated storage and converters. Therefore, electrolyzers and fuel cells have also attracted much attention [4]. Herein, a brief overview of typical secondary batteries, supercapacitors, fuel cells, and water electrolyzers is presented.
Figure 1.1 Schematics of typical systems for electrochemical energy storage and conversion.
Source: Modified from Shen et al. [2]; © 2016, Taylor & Francis Group.
1.1.1 Secondary Batteries and Supercapacitors
Currently, secondary batteries and supercapacitors are regarded as the most efficient electrochemical systems for electric energy storage and conversion. As a typical secondary battery, lithium‐ion battery has been widely studied and commercialized. The working mechanism of lithium‐ion battery is shown in Figure 1.2. It involves a reversible intercalation/deintercalation of Li ions into/from host materials, combined with electron flow through the external circuit in the charging/discharging process [5]. Taking a commercial lithium‐ion battery as an example, graphite and layered LiCoO2 are usually employed as anode host and cathode host, respectively. A mixture of lithium‐containing salt (e.g. LiPF6) and organic solvents (e.g. diethyl carbonate and ethylene carbonate) is commonly used as an electrolyte. The chemical reactions during the charging and discharging process are shown as below:
Figure 1.2 Illustration of the charging/discharging process within a lithium‐ion battery, composed of a graphite anode and a LiCoO2 cathode.
Source: Reproduced with permission from Manthiram et al. [5]; © 2008, The Royal Society of Chemistry.
As a “rocking chair” battery, the energy storage and release of the lithium‐ion battery primarily depend on the “rock” of Li ions between cathode and anode. As compared with Ni‐based battery and lead–acid battery, the lithium‐ion battery possesses characteristics of higher energy density and longer lifetime. Moreover, the lithium‐ion battery is easier to be integrated into portable devices.
Based on the energy storage mechanisms, supercapacitors are primarily classified into electric double‐layer capacitors (EDLCs) and pseudocapacitors (Figure 1.3) [7]. No matter what kind of mechanism, the charge storage occurs only on the electrode surface without ion diffusion within the electrode bulk, which endows supercapacitors with a higher power density (∼10 kW kg–1) but lower energy density (<10 Wh kg–1) than lithium‐ion battery [6]. The EDLC stores energy through the fast adsorption and desorption of electrolyte ions at the electrode/electrolyte interface, which forms the electric double layer during the charging/discharging process. The pseudocapacitor reversibly stores energy via Faradaic reactions or surface redox reactions, which also occur at the electrode surface [8].
Figure 1.3 Schematic of energy storage mechanisms of (a) an EDLC and (b) a pseudocapacitor.
Source: Reproduced with permission from Simon et al. [6]; © 2011, Materials Research Society.
Figure 1.4 Schematic of a PEMFC.
Source: Reproduced with permission from Manthiram et al. [5]; © 2008, The Royal Society of Chemistry.
1.1.2 Fuel Cells and Electrolyzers
Fuel cells are promising energy‐conversion devices because they can show high conversion efficiency besides being environment friendly. Among the different kinds of fuel cells, the proton exchange membrane fuel cell (PEMFC) is widely studied by virtue of its high energy delivery and low working temperature (<100 °C) [9,10]. Figure 1.4 shows the working process of a PEMFC that uses oxygen and hydrogen as oxidant and fuel, respectively [5]. H+ ions are generated through the electrocatalytic oxidation of H2 gas on the surface of an anode with Pt catalyst, which further migrates through a Nafion membrane with high proton conductivity. Meanwhile, the electrons move from anode to cathode through an external circuit and electrocatalytically reduce O2 gas to O2− ions on the cathode surface with the assistance of Pt catalyst. Water is produced by the combination of the H+ and O2− ions. Thus, the chemical energy involved in reaction 1.4 is converted into electricity:
Contrary to fuel cells, electrolyzers convert electric energy to chemical energy. Figure 1.5 displays a schematic representation of a water electrolyzer, which mainly consists of a cathode, an anode, an electrolyte, and an external power. At a critical voltage, electrons flow from the power source to the cathode and reduce H+ ions to H2 gas. At the same time, OH− ions move to the anode through the electrolyte to keep an electrical charge balance. O2 gas is then generated by oxidization of OH− ions by giving away electrons. Then, the electrons flow back to the power source. The half‐reactions occurring on the electrodes are represented below:
Figure 1.5 Schematic of a water electrolyzer.
Source: Reproduced with permission from Ma et al. [11]; © 2008, Elsevier Ltd.
1.2 Materials for Electrochemical Energy Storage and Conversion
Materials (especially electrode materials) play very important roles in the performance of the aforementioned devices. Great efforts have been devoted to developing novel materials to improve the device's performance. Herein, we review typical materials for lithium‐ion batteries, supercapacitors, and electrocatalysis (especially for oxygen reduction and evolution reactions).
1.2.1 Materials for Lithium‐Ion Batteries
Based on the lithium‐ion storage mechanism, the anode materials for the lithium‐ion battery can be classified into intercalated‐type materials (e.g. graphite, carbon nanotubes, and Li4Ti5O12), conversion‐type materials (e.g. SnO2, V2O5, and MoS2), alloy‐type materials (e.g. Si and Sn), and organic materials (e.g. carboxylates) [12] (Figure 1.6). To date, graphite is the most used anode material owing to its low cost, good thermal stability, and low working potential. Although conversion‐type and alloy‐type anode materials have a high theoretical capacity, they commonly have poor electrical conductivity and show large volume change during the lithiation process, which results in low coulombic efficiency and short lifetime in practical cells. Layered transition metal oxides are generally used as cathode materials for lithium‐ion battery, such as LiFePO4, LiCoO2, LiMn2O4, and Li[NixCoyMnz]O2[13]. The electrolytes for lithium‐ion battery are mainly composed of lithium‐containing salt (e.g. LiPF6) and organic carbonate solvents (e.g. ethylene carbonate), which are used for the balance of fluidity and dielectric constant. As separator, electronically insulated polymer film (e.g. polypropylene) with high porosity is widely used to avoid the direct contact between cathode and anode as well as ensure fast lithium‐ion transport.
Figure 1.6 Different types of anode materials for lithium‐ion batteries.
Source: Reproduced with permission from Long et al. [12]; © 2009, The Royal Society of Chemistry.
1.2.2 Materials for Supercapacitors
Carbon materials (e.g. activated carbons, graphene, carbon nanotubes, and porous carbons) have been employed as electrode materials for EDLC owing to their easy processing, large specific surface area, high electronic conductivity, and good chemical stability. Generally, the capacitance of EDLCs can be enlarged when the specific surface area of carbon electrode material is increased. In addition to the high specific surface area, suitable porosity for accessible ions (e.g. pore shape, pore size, and pore size distribution) also significantly influences the capacitance. For instance, the hierarchical porous structure can facilitate ion insertion and diffusion, thus endowing carbon electrodes with high capacitance and good rate capability. The electrode materials for pseudocapacitor contribute capacitance by reversible and rapid redox reactions, occurring on the electrode surface. Metal oxides (e.g. RuO2), metal carbides (e.g. MXene), electronically conducting polymers (e.g. polyaniline), and functionalized nanocarbons (e.g. heteroatom‐doped graphene) are widely used as electrode materials for pseudocapacitor [6]. In addition, some biomaterials with functional groups (e.g. protein) are also electrode materials that can deliver pseudocapacitance [14]. The electrolytes for supercapacitors include aqueous and nonaqueous (including organic and ionic liquid) systems [15]. The two standards for choosing electrolytes are stable electrochemical window and high ionic conductivity, which determine the energy and power densities of the supercapacitors, respectively. In comparison with organic electrolytes (with wide electrochemical windows ranging from 2.5 to 3.5 V), alkali‐ (e.g. KOH) and acid‐based (e.g. H2SO4) aqueous electrolytes provide a higher ionic conductivity (up to ∼1 S cm−1) but a lower electrochemical window (1.0–1.8 V). Ionic liquid electrolytes show the widest electrochemical window (3.0–5.5 V) but the lowest ionic conductivity among these three electrolytes.
1.2.3 Materials for Oxygen Electrochemistry
The performance of water electrolyzers and fuel cells is primarily restricted by oxygen reduction reactions (ORRs) and oxygen evolution reactions (OERs) performance [16]. Although oxygen is a kind of clean and abundant resource, its efficient and controllable use is difficult because the sluggish kinetic processes of ORR and OER lead to the low device efficiency in acidic and alkaline electrolytes [17]. The electrocatalysts for ORR and OER can be divided into precious metallic catalysts, non‐noble metallic catalysts, and carbon‐based catalysts (Figure 1.7). Pt catalyst has been used as an ORR electrocatalyst since the 1960s, and it is still widely studied because it not only shows a superior ORR performance but also provides a relatively simple system for investigating the ORR mechanism [19]. Pt‐based alloy materials show more excellent ORR activity and stability than a pure Pt electrocatalyst. The selected secondary metals and the alloy architectures are of great importance to the performance of Pt‐based alloy electrocatalysts. Non‐noble metals (e.g. Ni‐, Fe‐, Co‐, and Mn‐based oxides) are the most promising candidates to Pt because of their better electrocatalysis activities in alkaline solutions [20,21]. By virtue of low cost and high electric conductivity, carbon materials with heteroatom doping (e.g. nitrogen, oxygen, sulfur, phosphor, boron) have attracted extensive attention as electrocatalysts for ORR and OER. However, precious metallic catalysts and non‐noble metallic catalysts generally show better activity and practical performance than carbon materials.
1.2.4 Biomass‐Derived Materials for Electrochemical Energy Storage and Conversion
It is well established that the ever‐increasing global energy demand and environmental degradation have resulted in a severe crisis in the sustainable development of the international community [22]. In this context, it is imperative to develop high‐performance energy storage and conversion devices to address the challenges. The assembly of the devices needs materials (e.g. electrode materials) that should not only show high performance but also have sustainability and low cost. Biomass‐derived materials are such kind of materials for the energy storage and conversion devices because of their excellent characteristics, which include: (i) As the most abundant carbon source in nature, biomass is derived from all life species (including animals, plants, and microorganisms); (ii) Biomass possesses inherently unique microarchitecture, which is beneficial for the design of microstructured materials (especially electrode materials). (iii) Some biomass also contains non‐carbon elements (e.g. nitrogen, oxygen, sulfur, and phosphor). These heteroatoms can be in situ doped into biomass‐derived carbons during the carbonization process, introducing additional active sites to enhance the performance of biomass‐derived carbon electrodes. Therefore, biomass‐derived materials have been widely prepared and used for electrochemical energy storage and conversion devices in recent years (Figure 1.8). Table 1.1 shows the properties and applications of the biomass‐derived materials for different devices [3].
Figure 1.7 Progress in the development of ORR electrochemical catalysts.
Source: Reproduced with permission from Chen et al. [18]; © 2012, John Wiley & Sons.
Figure 1.8 Schematic diagram showing the structure and properties of biomass‐derived materials.
Source: Reproduced with permission from Zheng et al. [23]; © 2020, The Royal Society of Chemistry.
1.3 Collagen‐Derived Materials for Electrochemical Energy Storage and Conversion
As one kind of natural fibrous protein, collagen exists in the connective tissue of animals. It is composed of 23 kinds of amino acids (mainly including glycine, proline, and alanine). Collagen consists of three polypeptide chains that assemble in a triple helix by hydrogen and hydrophobic bonds [24]. The polypeptide chains contain two identical chains (α1) and an additional chain (α2), which have slightly different chemical compositions. Figure 1.9 illustrates the hierarchical structure of a collagen triple helix. A single‐collagen fiber is called tropocollagen, which has a diameter of ∼1.6 nm and a length of ∼300 nm. So far, 28 different types of collagen have been discovered, which are divided into fibrillar and non‐fibrillar collagen based on their structures [26].
Table 1.1 Biomass‐derived materials for electrochemical energy storage and conversion [3].
Electrochemical energy storage and conversion devices
Roles of biomass‐derived materials
Biomass‐derived materials
Desired features of the biomass‐derived materials
Supercapacitor
Electrode
Porous/activated carbon
Porous, conducting, high specific surface area, double‐layer capacitance, functional groups, heteroatom doping, engineered pore structure
Lithium‐ion battery
Anode electrode
Hard/soft carbon
Micrographite domain for Li/Na intercalation, conducting, porosity
PEMFC
Electrocatalyst or catalyst support
Porous/activated carbon
Conducting, high specific surface area, heteroatom doping catalytic property for ORR
PEMFC
Gas diffusion layer
Porous/activated carbon, carbon cloth/felt
Conducting, high porosity, hydrophobic
Lithium‐ion battery; Supercapacitor
Electrode binder
Cellulose, chitosan, other polysaccharides
Polymer chain and binding ability, chemical stability, functional groups
Supercapacitor
Electrolyte
Organic acids and salts
Ion conductivity, stability over a reasonably wide potential window
Lithium‐ion battery; supercapacitor
Separator
Cellulose, fiber
Electron insulator, thin film, wettability, flexibility, mechanical strength, chemical stability
Source: Yu et al. [3]/John Wiley & Sons.
Figure 1.9 Overview of the hierarchical structure for collagen triple helix. (a, b) Schematic illustration of a collagen triple helix. (c) Schematic illustration of collagen fibrils. (d) Cross‐section image of collagen fibrils in skin. (e) Transmission electron microscopy image of collagen fibrils. (f) Atomic force microscope image of collagen fibrils.
Source: Sherman et al. [25]/with permission of © Elsevier Ltd.
As a soluble protein compound, gelatin is produced by partially hydrolyzing collagen within animals. During the hydrolysis process, three polypeptide chains are disentangled and the collagen molecules are dissociated into smaller molecules, after breaking the hydrogen bonds and hydrophobic bonds [27]. Thus, the structure, composition, and properties of gelatin are dependent on the collagen sources and types. It contains 18 kinds of amino acids. Different from collagen, gelatin consists of a relatively high content of nonpolar amino acids (>80%, such as glycine, proline, and alanine). In addition to essential physicochemical characteristics (e.g. solubility, transparency, and color), gelatin has unique rheological property, gel strength, and thermal stability, which are mainly dependent on its molecular structures [28]. Since the polypeptide chains are composed of various amino acids with rich carbon, nitrogen, oxygen, and sulfur atoms, collagen and gelatin can be converted into carbon materials by controllable carbonization. The collagen‐derived carbons have heteroatom doping and unique morphologies, which are derived from the structural compositions of collagen.
By virtue of their structures and compositions, the collagen‐derived materials (including gelatin and collagen‐derived carbons) show promising applications in electrochemical energy storage and conversion. Gelatin materials with and without modification have been used as various modifying agents for electrodes [29], separators [30], and electrolytes [31]. Collagen‐derived carbons with different morphology structures and chemical compositions have also been prepared by different methods. They have been used as electrodes or support materials for electrochemical energy storage (e.g. supercapacitors [32], alkali‐ion batteries [33], and lithium–sulfur batteries [34]) and electrochemical energy conversion (e.g. oxygen reduction reactions [35], oxygen evolution reactions [36], and hydrogen evolution reactions [37]), showing good performance and practical prospect.
This book presents basic knowledge of collagen, collagen‐derived materials, and their conventional synthesis and applications. Moreover, new strategies for the synthesis of advanced collagen‐derived materials and their multifunctional applications in electrochemical energy storage and conversion are also summarized.
References
1
Yoo, H.D., Markevich, E., Salitra, G. et al. (2014). On the challenge of developing advanced technologies for electrochemical energy storage and conversion.
Materials Today
17: 110–121.
2
Shen, J., Fang, D., Hong, Z., and Mei, C. (2015).
Electrochemical Energy: Advanced Materials and Technologies
. Florida: CRC Press.
3
Yu, F., Li, S., Chen, W. et al. (2019). Biomass‐derived materials for electrochemical energy storage and conversion: overview and perspectives.
Energy & Environmental Materials
2: 55–67.
4
Kalyanasundaram, K. and Grätzel, M. (2012). Themed issue: nanomaterials for energy conversion and storage.
Journal of Materials Chemistry
22: 24190–24194.
5
Manthiram, A., Vadivel Murugan, A., Sarkar, A., and Muraliganth, T. (2008). Nanostructured electrode materials for electrochemical energy storage and conversion.
Energy & Environmental Science
1: 621–638.
6
Simon, P. and Gogotsi, Y. (2008). Materials for electrochemical capacitors.
Nature Materials
7: 845–854.
7
Long, J.W., Bélanger, D., Brousse, T. et al. (2011). Asymmetric electrochemical capacitors‐stretching the limits of aqueous electrolytes.
MRS Bulletin
36: 513–522.
8
Conway, B.E. (1999).
Electrochemical Supercapacitors
. New York: Plenum Press.
9
Appleby, A.J. (1988).
Fuel cell handbook
. New York: Van Nostrand Reinhold Co. Inc.
10
Acres, G.J.K. (2001). Recent advances in fuel cell technology and its applications.
Journal of Power Sources
100: 60–66.
11
Ma, L., Sui, S., and Zhai, Y. (2009). Investigations on high performance proton exchange membrane water electrolyzer.
International Journal of Hydrogen Energy
34: 678–684.
12
Palacín, M.R. (2009). Recent advances in rechargeable battery materials: a chemist's perspective.
Chemical Society Reviews
38: 2565–2575.
13
Whittingham, M.S. (2004). Lithium batteries and cathode materials.
Chemical Reviews
104: 4271–4302.
14
Khairy, M. and El‐Safty, S.A. (2015). Promising supercapacitor electrodes based immobilization of proteins onto macroporous Ni foam materials.
Journal of Energy Chemistry
24: 31–38.
15
Béguin, F., Presser, V., Balducci, A., and Frackowiak, E. (2014). Carbons and electrolytes for advanced supercapacitors.
Advanced Materials
26: 2219–2251.
16
Jiao, Y., Zheng, Y., Jaroniec, M., and Qiao, S.Z. (2015). Design of electrocatalysts for oxygen‐ and hydrogen‐involving energy conversion reactions.
Chemical Society Reviews
44: 2060–2086.
17
Katsounaros, I., Cherevko, S., Zeradjanin, A.R., and Mayrhofer, K.J.J. (2014). Oxygen electrochemistry as a cornerstone for sustainable energy conversion.
Angewandte Chemie International Edition
53: 102–121.
18
Chen, Q., Tan, X., Liu, Y. et al. (2020). Biomass‐derived porous graphitic carbon materials for energy and environmental applications.
Journal of Materials Chemistry A
8: 5773–5811.
19
Gómez‐Marín, A.M., Rizo, R., and Feliu, J.M. (2014). Oxygen reduction reaction at Pt single crystals: a critical overview.
Catalysis Science & Technology
4: 1685–1698.
20
Frydendal, R., Paoli, E.A., Knudsen, B.P. et al. (2014). Benchmarking the stability of oxygen evolution reaction catalysts: the importance of monitoring mass losses.
ChemElectroChem
1: 2075–2081.
21
Gorlin, Y. and Jaramillo, T.F. (2010). A bifunctional nonprecious metal catalyst for oxygen reduction and water oxidation.
Journal of the American Chemical Society
132: 13612–13614.
22
Larcher, D. and Tarascon, J.M. (2015). Towards greener and more sustainable batteries for electric energy storage.
Nature Chemistry
7: 19–29.
23
Zheng, Y., Jiao, Y., Jaroniec, M. et al. (2012). Nanostructured metal‐free electrochemical catalysts for highly efficient oxygen reduction.
Small
8: 3550–3566.
24
Rich, A. and Crick, F.H.C. (1955). The structure of collagen.
Nature
176: 915–916.
25
Sherman, V.R., Yang, W., and Meyers, M.A. (2015). The materials science of collagen.
Journal of the Mechanical Behavior of Biomedical Materials
52: 22–50.
26
Shamhart, P.E. and Meszaros, J.G. (2010). Non‐fibrillar collagens: key mediators of post‐infarction cardiac remodeling?
Journal of Molecular and Cellular Cardiology
48: 530–537.
27
Alipal, J., Mohd Pu'ad, N.A.S., Lee, T.C. et al. (2021). A review of gelatin: properties, sources, process, applications, and commercialisation.
Materials Today: Proceedings
42: 240–250.
28
Kozlov, P.V. and Burdygina, G.I. (1983). The structure and properties of solid gelatin and the principles of their modification.
Polymer
24: 651–666.
29
Chen, M., Chen, Z., Fu, X., and Zhong, W.‐H. (2020). A Janus protein‐based nanofabric for trapping polysulfides and stabilizing lithium metal in lithium–sulfur batteries.
Journal of Materials Chemistry A
8: 7377–7389.
30
Liu, N., Huang, B., Wang, W. et al. (2016). Modified separator using thin carbon layer obtained from its cathode for advanced lithium sulfur batteries.
ACS Applied Materials & Interfaces
8: 16101–16107.
31
Liu, Y., Shi, Q., Wu, Y. et al. (2021). Highly efficient dendrite suppressor and corrosion inhibitor based on gelatin/Mn
2+
co‐additives for aqueous rechargeable zinc‐manganese dioxide battery.
Chemical Engineering Journal
407, 127189.
32
Chen, W., Zhang, H., Huang, Y., and Wang, W. (2010). A fish scale based hierarchical lamellar porous carbon material obtained using a natural template for high performance electrochemical capacitors.
Journal of Materials Chemistry
20: 4773–4775.
33
Niu, J., Shao, R., Liang, J. et al. (2017). Biomass‐derived mesopore‐dominant porous carbons with large specific surface area and high defect density as high performance electrode materials for Li‐ion batteries and supercapacitors.
Nano Energy
36: 322–330.
34
Wei, S., Zhang, H., Huang, Y. et al. (2011). Pig bone derived hierarchical porous carbon and its enhanced cycling performance of lithium–sulfur batteries.
Energy & Environmental Science
4: 736–740.
35
Liu, H., Cao, Y., Wang, F. et al. (2014). Pig bone derived hierarchical porous carbon‐supported platinum nanoparticles with superior electrocatalytic activity towards oxygen reduction reaction.
Electroanalysis
26: 1831–1839.
36
Guan, J., Zhang, Z., Ji, J. et al. (2017). Hydrothermal synthesis of highly dispersed Co
3
O
4
nanoparticles on biomass‐derived nitrogen‐doped hierarchically porous carbon networks as an efficient bifunctional electrocatalyst for oxygen reduction and evolution reactions.
ACS Applied Materials & Interfaces
9: 30662–30669.
37
Li, T., Liu, J., Song, Y., and Wang, F. (2018). Photochemical solid‐phase synthesis of platinum single atoms on nitrogen‐doped carbon with high loading as bifunctional catalysts for hydrogen evolution and oxygen reduction reactions.
ACS Catalysis
8: 8450–8458.
2Collagen
2.1 History of Collagen
The word “collagen” comes from Greek, which means “glue producer.” Collagen can be gradually hydrolyzed into water‐soluble gelatin (also referred to as animal glue) when it is treated with hot water. As the richest protein in animals, collagen is the primary composition for the connective tissues and extracellular matrices. By virtue of its unique structure, collagen can form insoluble fibers that endow animal tissues with high strength [1].
In the 1950s, modern studies on collagen started, especially at a molecular level. As typical researchers and works, Highberger et al. [2] and Schmitt et al. [3] used an electron microscope to characterize the structure of collagen molecule. Then, Ramachandran and Kartha [4] and Rich and Crick [5] developed the triple‐helical structure models of the collagen. Finally, Boedtker and Doty [6] measured the physical and chemical properties of the collagen in solution [7].
In the 1960s, detailed information about collagen and its structure was further revealed by Miller et al. through the investigation of protein chemistry and biochemistry [8,9]. Based on the electron microscope results, it was found that band‐shape‐like collagen fibrils with a length of 70 nm are composed of three different but homologous collagen types, including types I, II, and III. Type I collagen is the most abundant among them; type II is the main collagenous component within cartilage; type III coexists with type I with different content in most tissues. After the discovery of type II and III collagen, Kefalides reported that a specific collagen is also present within basement membranes, which was categorized as the type IV collagen [10]. Then, Kuhn et al. [11] and Timpl et al. [12] showed that the structure of the type IV collagen is obviously different from that of the collagen, which can form fibers.
In addition to the above collagens, the type VI, VII, IX, and X collagens were also reported subsequently. Their structures are all different from each other [13]. The detailed structural information of the collagens was gradually provided by different approaches, including electron microscopy, biosynthesis, immunology, and molecular biology methods [7]. Generally, all collagens have a triple‐helical domain. The formation of the triple‐helical structure is different from that of globular and nonhelical structures. The collagen molecules are synthesized intracellularly and then secreted into the extracellular space. After aggregation with other molecules, supramolecular structures are formed and stabilized by intermolecular covalent bonds [7].
Figure 2.1 Collagen triple‐helix structure.
Source: Reproduced with permission from Chmielewski [19]; © 2020, John Wiley and Sons.
2.2 Structure and Composition of Collagen
Collagens are the major components of connective tissues. They also exist in the interstitial tissue of parenchymal organs. The collagen ensures the stability and structural integrity of the tissues and organs. The role played by collagen in a specific organ determines its type and organization [14]. The collagen‐enriched tissues include cartilage, tendons, cornea, and the organic component of bone. In tendons, collagen forms parallel fibers that support high strength. In the cornea, collagen is stacked to ensure the least scattering of transmitting light. In extracellular matrix, collagen exists in the form of a gel that maintains the tissue structure. In bone, collagen forms a framework with the hydroxyapatites, which show high mechanical performance as a composite material [15].
In terms of composition, collagen has a repeated motif of Gly–X–Y. Gly is glycine while X and Y are other amino acids. The positions of X and Y are mostly occupied by proline and 4‐hydroxyproline, respectively [16,17]. Although collagens with different types have different compositions, all of them have the same characteristics, such as a right‐handed triple‐helix structure containing three polypeptide chains [18]. As shown in Figure 2.1, the collagen molecule has a long and rigid structure composed of three α chains that intertwine with each other to form a triple helix [19]. The collagen molecule shows a length of ∼300 nm and a diameter of 1.5 nm. The collagen fibers have high tensile strength because of the tight coupling α chains, which is higher than that of a steel wire.
Based on the genetic type, the triple‐helical motif can further form a major or minor part of the collagen molecule. In addition to collagenous domains, different noncollagenous parts also exist in the other regions of the collagen [20]. Specifically, three left‐handed helices form a supercoiled right‐handed structure in a rope‐like shape [21]. It should be noted that the three chains are also staggered by one residue relative to one another [22]. On the whole, the collagens are composed of continuous triple helix and short‐helical telopeptides. The telopeptides do not have triple‐helical structures without repeating Gly–X–Y units. Although the telopeptides only account for 2% of the collagen molecule, they are essential to the formation of collagen fibrils [23].
2.2.1 Amino‐Acid Residue and Triple‐Helix Structure
As mentioned above, the composition units of the collagen are amino‐acid residues, which were found early in the 1940s. Early studies have already shown that the general nature of the amino‐acid composition has a high uniformity although the collagen comes from different sources.
Each peptide of the collagen has ∼1050 amino‐acid units, including glycine, proline, hydroxyproline, and lysine residues [24]. Among these amino‐acid residues, glycine and proline residues play important roles in the formation of the triple‐helical structure. As the smallest amino‐acid residue, glycine residue occupies every third position in the polypeptide chain. The specific position for the glycine is because that glycine residue is small enough to stably occupy the narrow core within the triple‐helical structure. As a result, glycine residue accounted for about one‐third of the total number of the chain residues, including mammalian, amphibian, and avian collagens [25]. In addition to glycine residue, proline and hydroxyproline residues are also important components of collagen, which account for ∼25% of the amino‐acid residues within the polypeptide chain. These two imino acid residues have a unique characteristic in that the Cβ atom is linked to the peptide nitrogen by the side chain, resulting in a 5‐membered ring. The ring structures of proline and hydroxyproline residues act as “kinks” in the polypeptide chain, which are beneficial to the formation of the helical conformation. Specifically, the peptide unit links the amino‐acid residue with the imino acid residue, leading to its low freedom degree of rotation about the N—Cα bond. The restriction imposed on the orientation of the peptide unit can stabilize the collagen structure, endowing the collagen chain with high rigidity. As another amino‐acid residue of collagen, alanine residue accounts for ∼10% of all residues within the polypeptide chain. The other compositions (e.g. arginine, lysine, glutamic acid residues) in polar side chains account for ∼20% of the amino‐acid residues. Although these amino‐acid residues are not very essential to the triple‐helical structure, they play important roles in linkages of the triple chains to form the collagen fibrils [26].
It was known in early times that glycyl residues account for one‐third of the total number of residues in the polypeptide chain. However, there was no specific structure to explain the content of glycine residue until 1954 [4]. Ramachandran and Reddi proposed the structure that glycine residue occupies every third position in the polypeptide chain. The position of glycine residue cannot be substituted by other residues that have β‐carbon atoms. It is also assumed that all the peptide units in this structure should have their trans conformations, which is different from the previous structures. Figure 2.2a displays the projection of the triple‐chain structure down the central axis [26]. The structure is composed of three polypeptide chains (marked as A, B, and C). Every polypeptide is in the shape of a threefold helix with a pitch of 9 Å. The helical chains are related to each other by a threefold screw axis, having a left‐handed twist.
Figure 2.2 Projection of the triple‐helical structure of collagen. (a) Indication of the postulated hydrogen bonds between chains B and C. (b) Indication of the angles and heights of the α‐carbon atoms in the chains.
Source: Modified from Ramachandran and Reddi [26]; © 1976, Springer Nature.
As shown in Figure 2.2a, the three chains are held together by hydrogen bonds [26]. In addition to the backbone of chain A, the atoms connected to the α‐carbon atoms are also marked in Figure 2.2b [26]. It is shown that the bonds connecting the β‐carbon atoms to C2α and C3α point away from the triple‐helix center, while the bonds connecting two hydrogen atoms to C1α (as part of a glycine residue) point to the triple‐helix center. It should be noted that there is no space for β‐carbon atoms to form in this central region. If Cβ occurred at position 1, the three chains would be separated from one another. In this case, the hydrogen bonds linking the chains could not be formed since the relevant bond length was too large to maintain stability. Therefore, it can be concluded that only the side chain of glycyl residue can be located at C1α in the chains. Also, the residue at every symmetry‐related atom (e.g. C4α, C7α, etc.) can only be glycine. Thus, glycine residue must occur at every third position in the collagen chain to maintain the triple‐helical structure. Different from position 1, it is easy to fix a prolyl side chain at position 2 or 3. The dihedral angle for proline residue has a limited range, which is perfectly satisfactory in the above structure. It should be noted that the positions 2 and 3 are not always occupied by imino acid residues (proline and hydroxyproline residues) although they can be fittingly located at these positions without distorting the main structure of the chains. Experimental evidence further confirmed the above speculation. A complete amino‐acid sequence of one peptide chain showed that proline and hydroxyproline residues occur only in the positions 2 and 3. Moreover, it is revealed that hydroxyproline residue occurs only in position 3 while proline residue can occur in both positions. The unique occupation of hydroxyproline residue in the chain is very important to understand the hydrogen bonding within the triple‐helical structure and the stability of collagen structure [26].
Engel and Bächinger further illustrate the triple‐helical structure of collagen in detail. As shown in Figure 2.3, the three helices are staggered by one residue relative to each other, supercoiling along a common axis into a right‐handed triple helix. The repeated sequence of Gly–X–Y is essential to the superhelical formation. There are three residues in the straight and non‐supercoiled polyproline‐II‐helix every turn, while the residues of glycine are in the face of each other in the interior of the helix structure (Figure 2.3b) [27]. Since the side chain at the Cα is larger than that at H, the hydrogen bond would not be formed between the backbone NH‐group of glycine and the backbone CO‐group of the residue at X position within the adjacent chain. These hydrogen bonds play important roles in the structural stability. If there are other residues (in addition to proline and hydroxyproline) in the chains, the isolated polyproline‐II‐helices would be unstable [27].
Figure 2.3 Collagen triple‐helix structure in which glycine occupies position 1, while proline occupies positions 2 and 3: (a) Side view, three left‐handed polyproline‐II‐type helices; (b) side view, the right‐handed triple helix (dashed lines show the Cα positions); (c) top view (dashed lines show the hydrogen bond positions). The scale bars are indicated in nm.
Source: Reproduced with permission from Brinckmann et al. [27]; © 2005, Springer Nature.
As shown in Figure 2.3
