Semiconductor Solar Photocatalysts E-Book

• Herausgeber: Wiley-VCH GmbH
• Kategorie: Wissenschaft und neue Technologien
• Sprache: Englisch

Seitenzahl: 834

Veröffentlichungsjahr: 2021

Beschreibung

Provides a timely overview of basic principles and significant advances of semiconductor-based photocatalysts for solar energy conversion 

Semiconductor Solar Photocatalysts: Fundamentals and Applications presents a systematic, in-depth summary of both fundamental and cutting-edge research in novel photocatalytic systems. Focusing on photocatalysts with vast potential for efficient utilization of solar energy, this up-to-date volume covers heterojunction systems, graphene-based photocatalysts, organic semiconductor photocatalysts, metal sulfide semiconductor photocatalysts, and graphitic carbon nitride-based photocatalysts. 

Organized into six chapters, the text opens with a detailed introduction to the history, design principles, modification strategies, and performance evaluation methods of solar energy photocatalysis. The remaining chapters provide detailed discussion of various novel photocatalytic systems such as direct Z-scheme and S-scheme photocatalysts, organic polymers, and covalent organic frameworks. This authoritative resource: 

• Explains the essential concepts of solar energy photocatalysis and heterojunction systems for photocatalysis 
• Reviews interesting structures and new applications of semiconductor photocatalysts 
• Features contributions from an international panel of leading researchers in the field 
• Includes extensive references and numerous tables, figures, and color illustrations  

Semiconductor Solar Photocatalysts: Fundamentals and Applications is valuable resource for all catalytic chemists, materials scientists, inorganic and physical chemists, chemical engineers, and physicists working in the semiconductor industry. 

Leseprobe

Table of Contents

Cover

Title Page

Copyright

1 The Fundamentals of Solar Energy Photocatalysis

1.1 Background

1.2 History of Solar Energy Photocatalysis

1.3 Fundamental Principles of Solar Energy Photocatalysis

1.4 Design, Development, and Modification of Semiconductor Photocatalysts

1.5 Processes and Evaluation of Solar Energy Photocatalysis

1.6 The Scope of This Book

Acknowledgments

References

2 Heterojunction Systems for Photocatalysis

2.1 Introduction

2.2 Classification of Heterojunction Photocatalysts

2.3 Evaluation of the Heterojunction Photocatalysts

2.4 Applications

2.5 Summary and Future Perspective

References

3 Graphene‐Based Photocatalysts

3.1 Introduction

3.2 Graphene and Its Derivatives

3.3 General Preparation Techniques of Graphene in Photocatalysis

3.4 General Advantages of Graphene

3.5 Characterization Methods

3.6 Recent Development in Graphene‐Based Photocatalysts

3.7 Summary and Concluding Remarks

Acknowledgments

References

4 Metal Sulfide Semiconductor Photocatalysts

4.1 Introduction

4.2 General View of Metal Sulfide Photocatalysts

4.3 Synthesis of Metal Sulfide Photocatalysts

4.4 CdS‐Based Photocatalyst

4.5 In

2

S

3

‐Based Photocatalysts

4.6 SnS

2

‐Based Photocatalysts

4.7 Cu

2

S‐Based Photocatalysts

4.8 Other Metal Sulfide Photocatalysts

4.9 Energy and Environmental Applications

4.10 Conclusions and Outlook

References

5 Organic Semiconductor Photocatalysts

5.1 Introduction

5.2 MOFs Photocatalysts

5.3 Organic Polymer Photocatalysts

5.4 COFs Photocatalysts

5.5 Conclusions and Outlook

References

6 Graphitic Carbon Nitride‐Based Photocatalysts

6.1 Introduction

6.2 Structure of g‐C

3

N

4

6.3 Preparation of g‐C

3

N

4

‐Based Photocatalysts

6.4 Main Photocatalytic Applications of g‐C

3

N

4

‐Based Photocatalysts

6.5 Strategies for Optimizing Photocatalytic Performance of g‐C

3

N

4

6.6 Challenges and Prospects

References

Index

End User License Agreement

List of Tables

Chapter 1

Table 1.1 Some crucial advances in the development of efficient heterogeneou...

Table 1.2 Standard redox potentials for selected species.

Table 1.3 Comparison of the bandgap structures and charge carrier dynamics f...

Table 1.4 The standard molar enthalpy

and the Gibbs free energy

for the r...

Table 1.5 The standard molar enthalpy

and the Gibbs free energy

of CO

2

hy...

Chapter 5

Table 5.1 Screening of the reaction conditions [36].

a)

Table 5.2 Photoreductive dehalogenation reaction of phenacyl bromide and its...

Table 5.3 Photocatalytic α‐alkylation of aldehydes by COF‐JLU22 [109].

a)

Table 5.4 Photocatalytic oxidation of secondary amines to imines by Por‐sp2c...

Table 5.5 Photocatalytic activity test of LZU‐190 in oxidative hydroxylation...

Table 5.6 TpTt for photoisomerization of alkene substrates [112].

a)

,b)

List of Illustrations

Chapter 1

Figure 1.1 The number of publications on photocatalysis found by searching w...

Figure 1.2 Photocatalytic mechanisms for (a) inorganic (TiO

2

, CdS, WO

3

, ZnO,...

Figure 1.3 The reduction and oxidation half reactions in different photocata...

Figure 1.4 Band positions and potential applications of some typical photoca...

Figure 1.5 Kinetic processes of photocatalysis: (1) light harvesting, (2) th...

Figure 1.6 (a) Schematic illustration of charge carrier relaxation following...

Figure 1.7 Design rules for heterogeneous photocatalysts.

Figure 1.8 The roles of various kinds of elements in designing and developin...

Figure 1.9 Schematic illustration of four kinds of photocorrosion: (a) reduc...

Figure 1.10 Band structures, thermodynamic reduction (black bar), and oxidat...

Figure 1.11 Strategies for inhibiting photocorrosion of unstable semiconduct...

Figure 1.12 Classification of semiconductor photocatalysts.

Figure 1.13 Different photocatalytic processes and the corresponding enhance...

Figure 1.14 Typical photocatalytic heterojunction systems: (a) type‐II heter...

Figure 1.15 Schematic illustration for six configurations of the semiconduct...

Figure 1.16 Systems for photocatalytic water splitting.

Figure 1.17 Three kinds of typical photocatalytic systems for water splittin...

Figure 1.18 Photocatalytic H

2

‐generation and O

2

‐generation reactions in the ...

Figure 1.19 Latimer–Frost diagram for the multi‐electron, multi‐proton reduc...

Figure 1.20 Processes involved in photocatalytic CO

2

reduction over a hetero...

Figure 1.21 Factors influencing photocatalytic efficiency and corresponding ...

Figure 1.22 Typical strategies for selective CO

2

photoreduction.

Figure 1.23 Heterogeneous photodegradation systems for various pollutants....

Figure 1.24 Semiconductor modification strategies for photocatalytic degrada...

Figure 1.25 Characterization of some important properties of semiconductor p...

Chapter 2

Figure 2.1 Schematic illustration for the (a) type‐I, (b) type‐II, and (c) t...

Figure 2.2 Photogenerated charge carrier transfer mechanism on the p–n junct...

Figure 2.3 Schematic illustration for surface junction between the {001} and...

Figure 2.4 Photogenerated electron–hole separation pathway on direct Z‐schem...

Figure 2.5 Formation mechanism for the S‐scheme heterojunction of WO

3

/g‐C

3

N

4

Figure 2.6 Band structure of the commonly used semiconductors in photocataly...

Figure 2.7 (a) Mott–Schottky plots for the TiO

2

nanocube (TC) and TiO

2

trunc...

Figure 2.8 Ultraviolet photoelectron spectrum for Cu

2

O.

Figure 2.9 Mott–Schottky plots for (a) NiO and (b) g‐C

3

N

4

.

Figure 2.10 (a) Electrochemical impedance Nyquist plots for TiO

2

nanocrystal...

Figure 2.11 Photoluminescence (PL) spectra for g‐C

3

N

4

, g‐C

3

N

4

/graphene oxide...

Figure 2.12 Time‐resolved PL spectra for TiO

2

and an optimized TiO

2

/CdS S‐sc...

Figure 2.13 Normalized transient absorption decays at 850 nm of Ga

2

O

3

sample...

Figure 2.14 Scanning electron microscopy (SEM) images for the (a) BiVO

4

, (b)...

Figure 2.15 (a) Transmission electron microscopy (TEM) and (b) high‐resoluti...

Figure 2.16 Electron spin resonance (ESR) signals of the DMPO–

⋅

O

2

−

...

Figure 2.17 (a) Photoluminescence spectra of g‐C

3

N

4

/TiO

2

under light irradia...

Figure 2.18 High‐resolution (a) Ti 2p and (b) Cd 3d XPS spectra for TiO

2

/CdS...

Figure 2.19 (a) X‐ray diffraction (XRD) patterns for different samples. (b, ...

Figure 2.20 (a) Schematic illustration for the preparation procedure of the ...

Figure 2.21 (a–e) SEM images of the TiO

2

nanocrystals with different exposed...

Figure 2.22 (a–c) Field emission scanning electron microscopy (FESEM) (a), T...

Figure 2.23 (a–c) SEM images for Au/MnO

x

/BiVO

4

(a), Pt/MnO

x

/BiVO

4

(b), and A...

Figure 2.24 (a) XRD patterns for Cu

3

P/CdS p–n junction with 0 (CdS), 0.03 (C...

Figure 2.25 (a, b) TEM images with low (a) and high (b) magnifications for t...

Figure 2.26 (a) Schematic illustration for the preparation procedure of the ...

Figure 2.27 (a) Schematic illustration for the enhancement mechanism for the...

Figure 2.28 (a) Preparation procedure for the TiO

2

/NiS core–shell nanofiber....

Figure 2.29 (a) Light absorption spectra for the samples cooled down through...

Figure 2.30 (a) ζ potentials for the bulk WO

3

, WO

3

nanosheets, and g‐C

3

N

4

. (...

Figure 2.31 (a–c) XRD patterns (a), light absorption spectra (b), and photoc...

Figure 2.32 (a) Schematic illustration of the preparation procedure of the A...

Figure 2.33 (a–c) Electron microscopy images of the TiO

2

nanocrystals prepar...

Figure 2.34 (a, b) SEM (a) and TEM (b) images for the Cu

2

O/TiO

2

p–n junction...

Figure 2.35 (a–d) Elemental mapping images of the W (a), O (b), Cd (c), and ...

Figure 2.36 (a) XRD patterns, (b) CO

2

adsorption isotherms, and (c) transien...

Figure 2.37 (a, b) SEM images for the TiO

2

(a) and TiO

2

/CdS (b). (c) TEM ima...

Figure 2.38 (a) Thermogravimetric analysis (TGA) curve for g‐C

3

N

4

, ZnO, and ...

Figure 2.39 (a–c) TEM (a,b) and HRTEM (c) images for CdS/TiO

2

hollow microsp...

Figure 2.40 (a,b) TEM (a) and HRTEM (b) images of g‐C

3

N

4

/ZnMoCdS. (c) Light ...

Figure 2.41 (a–c) SEM (a,b) and TEM (c) images of the AgCl/δ‐Bi

2

O

3

. (d) XRD ...

Figure 2.42 (a) Schematic illustration for the preparation procedure for AgI...

Figure 2.43 (a) Nitrogen adsorption–desorption isotherms for g‐C

3

N

4

(GCN) an...

Figure 2.44 (a–c) SEM images of the g‐C

3

N

4

/BiVO

4

with a g‐C

3

N

4

to BiVO

4

mola...

Figure 2.45 (a) Side‐view SEM image of the optimized SnO

2

/TiO

2

as an indicat...

Figure 2.46 Photocatalytic acetone degradation performance of the anatase/br...

Figure 2.47 (a, b) TEM (a) and HRTEM (b) images for a sample containing anat...

Figure 2.48 (a, b) XRD patterns (a) and Raman spectra (b) for the BiVO

4

, CeO

Figure 2.49 (a) SEM images with high and low (inset) magnification for the N...

Figure 2.50 (a–d) SEM images for the BiOI samples prepared by adding 1 (a, B...

Figure 2.51 (a–c) SEM images for the TiO

2

microcrystals loaded with Pt using...

Figure 2.52 (a, b) TEM (a) and HRTEM (b) images for the optimized g‐C

3

N

4

/TiO

Figure 2.53 (a) TEM image of the Fe

3

O

4

@CdS type‐II heterojunction photocatal...

Figure 2.54 (a–h) SEM images of the BiOI (a) and BiWO

6

/BiOI with different B...

Figure 2.55 (a, b) SEM (a) and TEM (b) images for the TiO

2

prepared using di...

Figure 2.56 (a, b) SEM (a) and TEM (b) images for the optimized AgQDs/Bi

2

S

3

/...

Figure 2.57 (a) TPRL spectra for the different prepared samples and (inset) ...

Chapter 3

Figure 3.1 Schematic illustration for the preparation procedures of rGO, inc...

Figure 3.2 (a) Tauc plots of GO prepared with different H

3

PO

4

contents inclu...

Figure 3.3 Schematic illustration of the GO‐Ag

3

PO

4

direct Z‐scheme photocata...

Figure 3.4 (a) TEM image of the P25/graphene composite. (b) Electrochemical ...

Figure 3.5 Comparison of the photocatalytic H

2

production performance of the...

Figure 3.6 Schematic illustration for (a) the suspension of Ru/SrTiO

3

and Pr...

Figure 3.7 TEM images of the (a) GQDs and (b) GQDs/g‐C

3

N

4

. (c) Electrochemic...

Figure 3.8 (a) AFM image of the GQDs. Light absorption spectra of the (b) GQ...

Figure 3.9 Up‐converted PL spectra of the GQDs at different excitation wavel...

Figure 3.10 Schematic illustration for the preparation procedure of the CdS/...

Figure 3.11 (a) Schematic illustration of the preparation procedures of the ...

Figure 3.12 Schematic illustration of the preparation procedure for the 3D g...

Figure 3.13 Schematic illustration of the (a) experimental setup and (b) for...

Figure 3.14 Schematic illustration for the preparation procedure of the N‐do...

Figure 3.15 (a) Schematic illustration for the photogenerated charge carrier...

Figure 3.16 (a) Schematic illustration for the photothermal effect on the se...

Figure 3.17 Comparison of the specific surface area of (a) graphite and (b) ...

Figure 3.18 (a) Schematic illustration for the protection of graphene on sem...

Figure 3.19 (a) Schematic illustration of the graphene‐assisted semiconducto...

Figure 3.20 TEM images of (a) graphene nanosheets and (b) graphene nanosheet...

Figure 3.21 (a) TEM and (b) HRTEM images of the CdS‐loaded graphene nanoshee...

Figure 3.22 TEM image of the GQDs and their corresponding size distribution,...

Figure 3.23 AFM images of the (a) rGO and (b) GQDs and their corresponding t...

Figure 3.24 (a) Raman spectra for various carbon‐based materials, including ...

Figure 3.25 High‐resolution XPS spectra of C 1s region for the GO and rGO/Ti...

Figure 3.26 High‐resolution XPS spectra of (a) C 1s and (b) O 1s region for ...

Figure 3.27 Photocatalytic performance of the P25, P25/CNTs, and P25/G (P25/...

Figure 3.28 (a) Photocatalytic benzyl alcohol oxidation performance of the T...

Figure 3.29 SEM images of the (a, b) TiO

2

nanoflowers and (c, d) 1 wt% graph...

Figure 3.30 (a) Schematic illustration of the preparation procedure of the g...

Figure 3.31 (a, b) TEM and (c, d) HRTEM images of the TiO

2

loaded with 0.5 w...

Figure 3.32 (a) Light absorption spectra of the P25 (P), graphene‐loaded P25...

Figure 3.33 (a) Comparison of the photocatalytic CO

2

reduction performance o...

Figure 3.34 Schematic illustration of the photogenerated charge carrier sepa...

Figure 3.35 (a) TEM and (b) HRTEM images of the ZnO/graphene. (c) Light abso...

Figure 3.36 (a) Schematic illustration for the preparation procedure of the ...

Figure 3.37 (a) Schematic illustration for the preparation of the ZnO/GO com...

Figure 3.38 (a) High‐resolution C 1s XPS spectra of the GO and Bi

2

WO

6

/graphe...

Figure 3.39 (a) Light absorption spectra of the Bi

2

WO

6

, Ag/Bi

2

WO

6

, G/Bi

2

WO

6

,...

Figure 3.40 ESR spectra of the AgI/BiOBr/rGO for (a) DMPO–

⋅

O

2

−

a...

Figure 3.41 (a) TEM and HRTEM (inset) images of the Cu

2

O/graphene. (b) Compa...

Figure 3.42 High‐resolution XPS spectra of (a) C 1s and (b) Cu 2p for Cu

2

O/r...

Figure 3.43 (a) Light absorption spectra of the CdS (G0) and CdS loaded with...

Figure 3.44 (a) Schematic illustration for the preparation procedure of the ...

Figure 3.45 (a, b) 2D and (c) 3D AFM images of the CdS QDs. (d, e) 2D and (f...

Figure 3.46 (a–d) SEM images of the samples obtained at each step in the pre...

Figure 3.47 (a) Schematic illustration for the TiO

2

/G/CdS (TGC). (b, c) Comp...

Figure 3.48 (a–d) SEM images of the ZIS, CQDs/ZIS, CNTs/ZIS, and rGO/ZIS. (e...

Figure 3.49 Electrochemical impedance spectroscopy of the MoS

2

and MoS

2

load...

Figure 3.50 (a) Light absorption spectra for different samples: N‐doped grap...

Figure 3.51 (a) Schematic illustration of the preparation procedure for the ...

Figure 3.52 TEM images of the (a) GO and (b) g‐C

3

N

4

/graphene.

Figure 3.53 (a) SEM, (b) TEM, and (c) HRTEM images of the g‐C

3

N

4

/rGO. (d) Di...

Figure 3.54 (a) TEM and (b) HRTEM images of the 15N‐CNU. (c) Light absorptio...

Figure 3.55 (a) Preparation procedure for the g‐C

3

N

4

/GO aerogel. SEM images ...

Figure 3.56 Schematic illustration for the photogenerated charge carrier mig...

Figure 3.57 Schematic illustration of the photogenerated charge carrier migr...

Figure 3.58 (a) Schematic illustration for the preparation procedure of the ...

Figure 3.59 (a) Schematic illustration for the preparation procedure of the ...

Figure 3.60 (a) Light absorption spectra of the graphene oxide (GrO), NH

2

‐mo...

Figure 3.61 (a) Light absorption of the MIL‐125 loaded with different conten...

Figure 3.62 (a) Photocurrent plots and (b) PL spectra for the NH

2

‐modified U...

Figure 3.63 (a) Mott–Schottky plots of the UiO‐66. (b) Schematic illustratio...

Chapter 4

Figure 4.1 Energy distribution diagram of different wave bands in the solar ...

Figure 4.2 Commonly reported metal sulfides for photocatalysis.

Figure 4.3 A brief description of strategies for enhancing photocatalytic pe...

Figure 4.4 The main synthetic methods for metal sulfide photocatalysts.

Figure 4.5 (a) SEM image of NiS/Zn

0.5

Cd

0.5

S/RGO sample and (b) EDX pattern o...

Figure 4.6 (a) X‐ray diffraction patterns of the ZnIn

2

S

4

synthesized without...

Figure 4.7 FESEM images of CdS nanomaterials synthesized in different solven...

Figure 4.8 The adsorption of solvent molecules on the (100) surfaces of CdS:...

Figure 4.9 (a) Schematic illustration of the preparation process of RGO–CdS ...

Figure 4.10 (a) Schematic illustration of the preparation process of N‐doped...

Figure 4.11 (a) The schematic illustration of a typical sacrificial template...

Figure 4.12 (a) The proposed structural generation mechanism of Ag

2

S/Ag/Ag

3

P...

Figure 4.13 (a) TEM image of the Zn

0.5

Cd

0.5

S sample. (b) UV–visible diffuse ...

Figure 4.14 Schematic diagram of zinc blende and wurtzite CdS crystal struct...

Figure 4.15 Classification of nanomaterials according to the dimensions.

Figure 4.16 TEM images of 0D CdS quantum dots prepared at different temperat...

Figure 4.17 TEM (a) and HRTEM images (b) of Co–Pi/CdS sample, (c) comparison...

Figure 4.18 (a) FESEM and (b) AFM images of 5‐CdS sample and (c) comparison ...

Figure 4.19 (a) A schematic illustration of the synthetic process of porous ...

Figure 4.20 TEM images of (a) B‐Pt/CdS and (b) P‐Pt/CdS. (c) The photocataly...

Figure 4.21 FESEM images of (a) CdS and (b) CdS/RGO composites. (c) Schemati...

Figure 4.22 Schematic illustration of electron–hole separation on (a) a type...

Figure 4.23 (a) TEM images of CdS/g‐C

3

N

4

composite. (b) UV–visible diffuse r...

Figure 4.24 (a) HRTEM images of Au@CdS/TiO

2

composite. (b) Photocatalytic ac...

Figure 4.25 (a) H

2

and O

2

evolution rates using BiVO

4

/CD/CdS samples with di...

Figure 4.26 FESEM images of (a, b) ZnO and (c, d) ZnO/CdS samples with diffe...

Figure 4.27 Calculated electrostatic potentials for both (101) faces of (a) ...

Figure 4.28 Crystal structure of (a) tetragonal β‐In

2

S

3

and (b) cubic β‐In

2

S

Figure 4.29 A description of the morphologies of In

2

S

3

photocatalysts.

Figure 4.30 (a) TEM images and (b) XRD pattern of In

2

S

3

nanoparticles. Photo...

Figure 4.31 (a) Illustration of the synthesis of MWCNT@MOF‐derived In

2

S

3

pho...

Figure 4.32 (a) Synthesis of In

2

S

3

by the space‐confined CVD method. (b, c) ...

Figure 4.33 SEM images of In

2

S

3

hollow microspheres prepared at 180 °C with ...

Figure 4.34 (a) Schematic diagram of the synthesis route for In

2

O

3

/In

2

S

3

mic...

Figure 4.35 (a) Photocatalytic H

2

production of different MnS/In

2

S

3

samples ...

Figure 4.36 (a) The surface potential of WO

3

‐based samples; lines 1–4 and li...

Figure 4.37 Electron microscopy images of SnS

2

nanomaterials with different ...

Figure 4.38 (a) SEM and (b) TEM images of Te/SnS

2

/Ag artificial nanoleaves. ...

Figure 4.39 (a) Efficiencies of Cr(VI) reduction over pure ZnIn

2

S

4

, SnS

2

, an...

Figure 4.40 (a) TEM and (b) HRTEM images of g‐C

3

N

4

/SnS

2

composites. Calculat...

Figure 4.41 (a) TEM image of Cu

2

S nanocrystals with an average diameter of c...

Figure 4.42 (a) TEM image of Cu

2

S nanowires hydrothermally synthesized at 17...

Figure 4.43 (a) FESEM and (b) TEM images of Cu

2

S nanoribbons. Source: Li et ...

Figure 4.44 (a) Schematic diagram of the growth process of hierarchical Cu

2

S...

Figure 4.45 (a) TEM image of the ZnO@Cu

2

S composite photocatalyst and (a1–a4...

Figure 4.46 (a) Schematic representation of the synthesis of Cu

2

S–MoS

2

nanoc...

Figure 4.47 Fine‐scanned XPS (a) Cu 2p

3/2

and (b) Au 4f

7/2

peaks of the Cu

2

S...

Figure 4.48 Band alignments of common metal sulfides.

Figure 4.49 Comparison of the photocatalytic activity of the R0, R5, R15, R2...

Figure 4.50 (a) Photocatalytic H

2

evolution amount of Cu

2

S nanosheet/TiO

2

an...

Figure 4.51 (a) Comparison of the photocatalytic activity of the CdS and CdS...

Figure 4.52 (a) UV–vis absorption of ZnIn

2

S

4

and Bi

2

S

3

–ZnIn

2

S

4

photocatalyst...

Figure 4.53 (a) Schematic illustration for the synthesis of MoS

2

/RGO composi...

Figure 4.54 (a) Schematic illustration of the synthesis of the CNF@SnS

2

memb...

Chapter 5

Figure 5.1 Synthesis of MOFs.

Figure 5.2 Representative MOFs. MOF‐5 [5], ZIF‐8 [5], NH

2

‐UiO‐66 [6], HKUST‐...

Figure 5.3 A brief description of strategies for photocatalytic performance ...

Figure 5.4 (a) The crystal structure of MIL‐68(Fe). Top: View along the chan...

Figure 5.5 (a)

Scanning electron microscopy

(

SEM

) images of NH

2

‐MIL‐125(Ti)....

Figure 5.6 (a) Design of SNNU‐110 through topological transformation by the ...

Figure 5.7 (a) Schematic formation of PMOFs. (b) Crystal structures of PMOF

‐

...

Figure 5.8 (a) Synthesis of doped UiO‐67. (b) SEM micrograph of intergrown n...

Figure 5.9 (a) Structural scheme, (b)

X‐ray powder diffraction

(

XRD

) p...

Figure 5.10 TEM images of AUN (a, b), PUN (d, e), Au (c), and Pt (d) size di...

Figure 5.11 TEM (a), HRTEM (b) images, and

scanning transmission electron mi

...

Figure 5.12 (a) Synthesis of Pd@NH

2

‐Uio‐66(Zr) and schematic illustration of...

Figure 5.13 (a) XRD patterns of NH

2

‐UiO‐66(Zr) and Cu

1

Pd

1

@NH

2

‐UiO‐66(Zr). (b...

Figure 5.14 (a) Structures of H

3

TATB and H

3

BTC ligands. (b) Observed and sim...

Figure 5.15 (a) Schematic representation of the preparation for the MOF UiO‐...

Figure 5.16 (a) Overall flowchart for fabrication of the CdS‐M68 NCs via a f...

Figure 5.17 (a) Structure of Pt‐loaded Ti‐MOF‐NH

2

. (b) XRD patterns of Ti‐MO...

Figure 5.18 (a) Photoreduction of deposited Pt nanoparticles and photocataly...

Figure 5.19 (a) Synthesis of phosphorescent Zr‐carboxylate MOFs (

1

and

2

) of...

Figure 5.20 (a) TEM images of 3% MoS

2

/(50%) U6–CdS. (b) Photocurrent spectra...

Figure 5.21 (a) Schematic illustration of the synthetic procedure of ZnO/ZnS...

Figure 5.22 (a) Photocatalytic CO

2

reduction over NH

2

‐MIL‐125(Ti) under visi...

Figure 5.23 (A) View of the 3D network of PCN‐222 featuring large channels r...

Figure 5.24 (a) A MOF/complex or MOF/ZIF system for CO

2

photoreduction with ...

Figure 5.25 (a) Synthetic procedures for MOF‐253‐Re(CO)3Cl and Ru‐MOF‐253‐Re...

Figure 5.26 TEM images for holey g‐C

3

N

4

(TCN) (a) and ZIF‐8 grafted g‐C

3

N

4

n...

Figure 5.27 (a) Schematic illumination of the synthesis of CdS MIL‐101(Cr). ...

Figure 5.28 (a) Scheme of photocatalytic routes for CO

2

reduction in MIL‐101...

Figure 5.29 TEM and high‐resolution TEM images of (a–c) CsPbBr

3

QDs, (d) UiO...

Figure 5.30 (A) The route for the synthesis of the CdS/UiO‐bpy/Co composites...

Figure 5.31 Reactions for synthesizing POPs.

Figure 5.32 (a) Schematic representation of the network structures of SBN‐0 ...

Figure 5.33 (a) Schematic representation of the mechanochemical synthesis of...

Figure 5.34 (a) The synthetic route of COP‐NT. (b) Absorption curves of MO u...

Figure 5.35 (A) Synthesis of microporous polymer networks by using SiO

2

NPs f...

Figure 5.36 (a) Thiol–yne modification of the poly(benzothiadiazole) network...

Figure 5.37 (a) Synthetic scheme for the synthesis of MPc‐CMPs. (b) Nitrogen...

Figure 5.38 (a) Synthetic scheme for the benzodifuran‐based CCP (BDF‐MON). (...

Figure 5.39 (a) Synthetic scheme for the rose bengal‐based conjugated microp...

Figure 5.40 Conjugated microporous polymers incorporating BODIPY moieties as...

Figure 5.41 (a) Illustration of the synthesis and idealized structures of th...

Figure 5.42 (a) Illustrated design and formation pathway of the thiophene‐ba...

Figure 5.43 (a) Polymer backbone structure of B‐BO

3

. (b) TEM image of B‐BO

3

...

Figure 5.44 (a) Molecular structures of the building units for conjugated po...

Figure 5.45 (a) Synthetic routes to the perylene‐containing conjugated micro...

Figure 5.46 (a) Structures of monomers and synthesis of PCP photocatalysts b...

Figure 5.47 (a) Structures of comonomers (M

0

–M

11

) used for the preparation o...

Figure 5.48 (a) Synthesis of the CMPs and the representative structures. (b)...

Figure 5.49 (a) Chemical structures of 1,3‐diyne linked PTEPB and PTEB photo...

Figure 5.50 (a) Synthetic procedure for the CTPs. (b) Band structure diagram...

Figure 5.51 (a) Schematic illustration of the formic acid production from CO

Figure 5.52 (a) Illustrated design and synthesis pathway of three triazine‐b...

Figure 5.53 (a) Synthetic procedure for PEosinY‐N (

N

 = 1–3) production. (b) ...

Figure 5.54 (a) Schematic illustration of light‐driven CO

2

reduction catalyz...

Figure 5.55 (a) Synthesis of Re‐metalated polypyridine‐based porous polycarb...

Figure 5.56 Structural diversity in COFs. COF‐5 [92], COF‐S‐SH [93], NiPc CO...

Figure 5.57 A brief description of COFs photocatalysts.

Figure 5.58 Reactions for synthesizing COFs.

Figure 5.59 Schematic presentation of the synthesis of TpTa‐COF (a) and Fe–T...

Figure 5.60 (a) Schematic illustration of the synthesis of MOF/COF hybrid ma...

Figure 5.61 (a) Schematic diagram, structure, and photographs of TPB‐BT‐COF,...

Figure 5.62 (a) Synthesis of COF‐JLU22 by imine condensation reaction. (b) O...

Figure 5.63 Synthesis and photocatalytic application of Por‐sp

2

c‐COF.

Figure 5.64 (a) One‐pot construction of benzoxazole‐linked COFs (LZU‐190, LZ...

Figure 5.65 Structure and photocatalytic application of TpTt.

Figure 5.66 Representation of synthesis of the TpPa‐2 and CdS‐COF hybrid for...

Figure 5.67 (a) Synthesis of TFPT–COF and its eclipsed structure (gray: carb...

Figure 5.68 (a) Synthesis of N

x

–COFs from N

x

–aldehydes and hydrazine. (b) TE...

Figure 5.69 (a) Illustration of synthetic procedures of g‐C

x

N

y

‐COFs. (b) UV/...

Figure 5.70 (a) Chemical structures of the fused sulfone‐based COF photocata...

Figure 5.71 Illustration of Pt‐PVP‐COFs photosystems for efficient photocata...

Figure 5.72 (a) Structures of N

2

‐COF and the cobaloxime cocatalysts used in ...

Figure 5.73 (a) Schematic illustration of the synthesis of NH

2

‐UiO‐66/TpPa‐1...

Figure 5.74 (a) Synthesis of CTF‐T1 and CTF‐T2. (b) Time course of H

2

evolut...

Figure 5.75 (a) Schematic illustration of the synthesis and photocatalytic h...

Figure 5.76 (a) Reaction mechanism for triazine formation in the synthesis o...

Figure 5.77 (a) The synthesis routes of CTF‐CS‐1 (CS is the abbreviation of ...

Figure 5.78 (a) Schematic synthesis of TTR‐COF and its application in photoc...

Figure 5.79 Structure and CO

2

photoreduction of Re‐COF.

Figure 5.80 (a) Schematic diagram for photocatalytic selective reduction of ...

Figure 5.81 (a) Schematic of the mechanism of TTCOF‐M CO

2

RR with H

2

O oxidati...

Figure 5.82 (a) Schematic illustration of synthesis of the COF‐367 NSs for p...

Chapter 6

Figure 6.1 (a) Triazine and (b) tri‐

s

‐triazine (heptazine) structures of g‐C

Figure 6.2 Schematic illustration of the main precursors and temperatures fo...

Figure 6.3 Reaction pathway for the preparation of g‐C

3

N

4

using cyanamide as...

Figure 6.4 Reaction pathway for the self‐polymerization of thiourea into g‐C

Figure 6.5 Reaction pathway for the self‐polymerization of urea into g‐C

3

N

4

...

Figure 6.6 (a) XRD patterns, (b) FTIR spectra, (c) UV–vis diffuse reflectanc...

Figure 6.7 (a) ζ potentials of bulk WO

3

, WO

3

nanosheets, and g‐C

3

N

4

nanoshee...

Figure 6.8 ζ potentials of g‐C

3

N

4

prepared by different precursors MCN (mela...

Figure 6.9 Schematic illustration of the synthesis process of the amorphous ...

Figure 6.10 Schematic of photocatalytic water splitting for H

2

and O

2

evolut...

Figure 6.11 Schematic of photocatalytic CO

2

reduction to generate solar fuel...

Figure 6.12 FESEM images of (a and b) ultrathin g‐C

3

N

4

nanosheets (NS‐CN) an...

Figure 6.13 (a) Powder XRD patterns of

crystalline g‐C

3

N

4

(

CCN

) and co...

Figure 6.14 (a) Nitrogen adsorption and desorption isotherms and correspondi...

Figure 6.15 (a) Transient photocurrent response, (b) electrochemical impedan...

Figure 6.16 UV–vis diffuse reflectance spectra and corresponding colors (ins...

Figure 6.17 (a) Schematic of the experimental procedure in tube furnace and ...

Figure 6.18 Electronic localization function of (a) pure g‐C

3

N

4

and (b) B‐do...

Figure 6.19 The structure diagram of P and Na codoping of g‐C

3

N

4

.

Figure 6.20 (a) Schematic illustration of the preparation process of Pt/g‐C

3

Figure 6.21 (a) Possible mechanism for photocatalytic H

2

evolution over CoS

x

Figure 6.22 Structure illustration of the g‐C

3

N

4

, graphdiyne, and graphdiyne...

Figure 6.23 Charge transfer in the conventional type‐II g‐C

3

N

4

‐based heteroj...

Figure 6.24 Z‐scheme charge transfer between semiconductors with (a) or with...

Figure 6.25 (a) HRTEM image of TiO

2

/g‐C

3

N

4

composite (U100). (b) Comparison ...

Figure 6.26 Electrostatic potentials of (a) the monolayer g‐C

3

N

4

(001) surfa...

Figure 6.27 Schematic illustration of 2D layered composites in comparison wi...

Figure 6.28 (a) Schematic diagram of preparation process for 2D/2D MnO

2

/g‐C

3

Figure 6.29 The schematic diagrams of charge transfer in (a) conventional ty...

Figure 6.30 (a) Schematic diagram of Pd atoms intercalated and surface ancho...

Guide

Cover

Table of Contents

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Index

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Semiconductor Solar Photocatalysts

Fundamentals and Applications

Edited by

Jiaguo Yu, Xin Li, and Jingxiang Low

Editors

Professor Jiaguo Yu

China Universityof Geosciences

Laboratory of Solar Fuel

Faculty of Materials Science and

Chemistry

388 Lumo Road

Wuhan 430074

China

Professor Xin Li

South China Agricultural University

Key Laboratory of Energy Plants Resources and Utilization

Guangzhou 510642

China

Dr. Jingxiang Low

University of Science and Technology of China

School of Chemistry and Materials Science

96 Jinzhai Road

Hefei 230026

China

Cover Design: ADAM DESIGN, Weinheim, Germany

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sky: © Xurzon / gettyimages

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1The Fundamentals of Solar Energy Photocatalysis

Xin Li1 and Jiaguo Yu2

1Institute of Biomass Engineering, South China Agricultural University, 483 Wushan Road, Tianhe District, Guangzhou, 510642, P. R. China

2China University of Geosciences, Laboratory of Solar Fuel, Faculty of Materials Science and Chemistry, 388 Lumo Road, Wuhan, 430074, P. R. China

1.1 Background

Solar energy semiconductor photocatalysis has long been considered to be the best solution to various kinds of energy and environmental problems. During the past decades, the solar energy semiconductor photocatalysis has attracted more and more attention. Based on Figure 1.1a, the total number of academic papers on the photocatalysis published since 1996 has reached 64 011, with increasing publication year by year. Especially, there are almost 8000 papers published in 2019 in the field of photocatalysis. Among all different research fields, the number of papers in photocatalytic pollutant degradation is the largest, which is much more than the total number of publications in both photocatalytic H2 evolution and CO2 reduction (Figure 1.1b).

So far, hundreds of solar energy semiconductor photocatalysts have been exploited and applied in the different photocatalytic fields, including the plasmonic metals, metal oxides/hydroxides, sulfides, nitrides, metal‐free polymers, organic semiconductors, and their composites. Although some reviews covered the progresses of these kinds of semiconductors, there are few books systematically summarizing the advances in these semiconductors. Therefore, it is timely to provide a comprehensive book to thoroughly elaborate the exploitation and application of typical kinds of solar energy semiconductors in the different photocatalytic fields. We believe that this book can help the researchers easily grasp the recent achievements for various kinds of semiconductors and inspire their new ideas in developing new solar energy semiconductors for efficient photocatalysis.

1.2 History of Solar Energy Photocatalysis

Due to its green and renewable advantages, photocatalysis has been one of the most active directions in the field of chemistry in recent years.

Figure 1.1 The number of publications on photocatalysis found by searching with the following keywords: (a) topic: (photoca*), (b) topic 1: (photoca*), and topic 2: (hydrogen or H‐2 or H2), (carbon dioxide or CO2 or CO‐2), or (degradat*).

Source: Science Core Collection 26 November 2019.

Semiconductor photocatalysis can be traced back to 1839. Becquerel [1] first discovered the photoelectric phenomenon, although he did not explain it theoretically.

In 1955, Brattain and Garrett [2] gave a reasonable explanation for the photoelectric phenomena, marking the birth of photoelectrochemistry.

Especially in 1972, Fujishima and Honda first found that n‐type semiconductor rutile TiO2 single crystal electrode could achieve the photocatalytic decomposition of H2O to O2 under the ultraviolet (UV) light (with 380 nm wavelength), while on the counter electrode Pt simultaneously produces H2[3]. This great discovery has caused a sensation all over the world, which revealed the possibility of using solar energy to decompose water for hydrogen production – or to convert solar energy directly into chemical energy – thus opening up a new era of semiconductor photocatalysis research and attracting worldwide attention. Because of its far‐reaching significance in the development of new energy and the protection of ecological environment, heterogeneous semiconductor photocatalysis has become a hot spot, attracting the extensive attention of researchers in many fields, such as chemistry, physics, and materials.

In the middle and late 1970s, Carey et al. [4] and Bard and coworker [5] utilized the TiO2 suspension to degrade polychlorinated biphenyls and cyanides, respectively, under UV irradiation, which set off a research upsurge of environmental photocatalysis technology with the main purpose of decomposing environmental pollutants.

Schrauzer also confirmed that TiO2 with rutile and anatase mixed crystal phases can realize the photocatalytic decomposition of chemisorbed water into H2 and O2 with a 2 : 1 stoichiometric ratio [6].

At the same time, Bard and his coworkers have guided and promoted the development of photoelectrochemistry. They first extended the theory of photoelectrochemistry (microelectrode model) to the photocatalysis of semiconductor particles, advancing the semiconductor photocatalysis technology greatly in theory. They not only used electron paramagnetic resonance (EPR) spectroscopy to characterize the free radicals such as hydroxyl (⋅OH) and hydroperoxyl (⋅OOH) radicals in the processes of photocatalytic oxidation and photocatalytic reduction of O2[7, 8], respectively, but also used Pt‐decorated TiO2 photocatalyst to decompose acetic acid for generating methane (CH4), which proved that the heterogeneous photocatalysis process has similar principles to the photoelectrochemical (PEC) process [9, 10]. In terms of its charge transfer mechanism, the suspended semiconductor particle photocatalyst can be regarded as a short‐circuited PEC cell [11, 12].

In 1978, Halmann found that CO2 dissolved in the electrolyte could be reduced to formic acid (HCOOH), formaldehyde, and methanol (CH3OH) by using p‐GaP single crystal, carbon rod, and K2HPO4–KH2PO4 buffer solution as cathode, anode, and electrolyte, respectively, under the necessary applied bias voltage [13].

In the same year, Somorjai first used SrTiO3 to achieve the photocatalytic conversion of CO2 and water vapor to CH4[14].

In 1979, Inoue et al. [15] systematically reported that WO3, TiO2, ZnO, CdS, GaP, SiC, and other semiconductor catalysts suspend in the saturated aqueous solution of CO2 could achieve the photoreduction of CO2 to HCOOH, formaldehyde (HCHO), CH3OH, and CH4 under the illumination of xenon lamp and high‐pressure mercury lamp. More importantly, the reaction mechanism of CO2 photoreduction was proposed.

In 1980, Kawai and Sakata reported that H2 was produced by photocatalytic reforming biomass and its derivatives (glycine, glutamic acid, proline, white gelatin protein) in water using Pt/RuO2/TiO2 photocatalyst. Only H2 and CO2 products were released from the photocatalytic processes [16].

Sequentially, Pt/TiO2[17] and (Pt) SrTiO3[18, 19] have also been proved to exhibit good photocatalytic activity for the decomposition of water into H2. Therefore, since the early 1980s, heterogeneous photocatalysis technology has gradually formed two main research directions: environmental photocatalysis and energy photocatalysis.

Along with the two main research directions, researchers from the fields of physics, chemistry, materials science, and environmental science have made a series of remarkable achievements in developing new semiconductor materials, revealing the mechanism of photocatalysis process and improving the quantum efficiency of photocatalysis reaction. Table 1.1 systematically summarizes a series of notable advances in the development of efficient heterogeneous photocatalysts. As seen from Table 1.1, among various kinds of photocatalysts, TiO2‐based photocatalysts were undoubtedly the most studied, because TiO2 has many advantages, such as low cost, nontoxicity, strong oxidation–reduction ability, light and chemical corrosion resistance, and excellent stability. However, it remains a great challenge to design and develop high‐performance TiO2‐based photocatalytic materials. The key problems lie in how to enhance the quantum efficiency of TiO2 photocatalysis, promote the separation of photogenerated charge carriers, and expand the visible light response range. So far, TiO2 modification methods have been widely developed, such as dye and quantum dot (QD) sensitization [30]; cocatalyst loading [17, 21–23, 70, 73, 74]; metal and non‐metal ion doping [31, 37, 39, 40]; reasonable control of defects and exposed crystal facets [57, 66, 67]; nanostructure modification (including the construction of colloidal nanocrystals, hierarchical structures, hollow microspheres, and nanosheet structures) [29, 44, 45, 52, 53, 77]; formation of heterojunctions (by coupling with other semiconductors and nanocarbon materials) [55, 74]; etc. The following are some examples.

Table 1.1 Some crucial advances in the development of efficient heterogeneous photocatalysts.

No.

Photocatalysts

Highlights

Group

References (year)

1

TiO

2

photoelectrode

The discovery of Fujishima–Honda effect of TiO

2

Fujishima and Honda

[3]

(1972)

2

TiO

2

powders

Photodechlorination of polychlorinated biphenyls

Carey

[4]

(1976)

3

TiO

2

powders

Photocatalytic oxidation of CN

−

in aqueous solutions

Bard

[5]

(1977)

4

TiO

2

powders

Overall water splitting on TiO

2

consisting of mixtures of anatase and rutile

Schrauzer

[6]

(1977)

5

Pt–TiO

2

particle systems

Bard's concept, “a short‐circuited photoelectrochemical cell”

Bard

[9

,

11

,

12

,

20]

(1978)

6

P‐type GaP photocathode

Photo‐assisted electrolytic reduction of CO

2

in aqueous phase

Halmann

[13]

(1978)

7

TiO

2

, CdS, and SiC powders

Photocatalytic reduction of carbon dioxide in aqueous suspensions of semiconductor powders

Inoue

[15]

(1979)

8

Pt/TiO

2

powders

Decompose H

2

O into H

2

and O

2

under UV irradiation

Sato and White

[17

,

21]

(1980)

9

RuO

2

/TiO

2

/Pt powders

Photocatalytic reforming of carbohydrates into hydrogen

Kawai

[16]

(1980)

10

Platinized or Pt‐free SrTiO

3

single crystals

Production of H

2

Wagner

[18

,

19]

(1980)

11

Pt and RuO

2

co‐loaded TiO

2

sol

First report on the photocatalytic water decomposition by loading dual cocatalysts (with a quantum yield of 30 ± 10%)

Grätzel

[22

,

23]

(1981)

12

SrTiO

3

–NiO

The utilization of NiO as H

2

‐evolution cocatalysts

Domen

[24]

(1982)

13

CdS–TiO

2

Improved photocatalytic efficiency through inter‐particle electron transfer

Grätzel

[25]

(1984)

14

Zn

x

Cd

1–

x

S solid solutions

The utilization of solid solutions for H

2

evolution

White

[26]

(1985)

15

SrTiO

3

–Ni@NiO

The utilization of Ni@NiO core/shell H

2

‐evolution cocatalysts

Domen

[27

,

28]

(1986)

16

TiO

2

particles

Size quantization effects of small‐particle titania

Anpo

[29]

(1987)

17

Colloidal TiO

2

films

TiO

2

‐based solar cells sensitized by Ru‐based dyes

Grätzel

[30]

(1991)

18

TiO

2

colloids

Metal ion‐doped quantum‐sized (2–4 nm) TiO

2

colloids

Hoffmann

[31]

(1994)

19

TiO

2

polycrystalline film

Light‐induced amphiphilic surface of TiO

2

Fujishima

[32]

(1997)

20

BiVO

4

particles

First report on the BiVO

4

photocatalyst

Kudo

[33

,

34]

(1998)

21

In

1–

x

Ni

x

TaO

4

(

x

 = 0–0.2) solid solutions

Ni‐doped indium–tantalum oxide

Zou

[35]

(2001)

22

(WO

3

or Fe

2

O

3

)/dye‐sensitized TiO

2

First report on the concept of “direct Z‐scheme”

Grätzel

[36]

(2001)

23

TiO

2

films/powders

First report on N‐doped TiO

2

Asahi

[37]

(2001)

24

Pt‐loaded anatase TiO

2

and rutile TiO

2

The Z‐scheme water splitting using IO

3

−

/I

−

redox mediator

Arakawa

[38]

(2001)

25

TiO

2

photoelectrodes

First report on C‐doped TiO

2

Khan

[39]

(2002)

26

TiO

2

powders

First report on F‐doped TiO

2

Yu

[40]

(2002)

27

Ta

3

N

5

First report on the Ta

3

N

5

photocatalyst

Domen

[41]

(2002)

28

TaON

First report on the TaON photocatalyst

Domen

[42]

(2002)

29

AgInZn

7

S

9

AgInZn

7

S

9

solid solution photocatalyst for H

2

evolution

Kudo

[43]

(2002)

30

Hierarchical TiO

2

First application of hierarchical TiO

2

in photocatalysis

Yu

[44

,

45]

(2003)

31

NiO/NaTaO

3

:La photocatalyst

An apparent quantum yield of 56% at 270 nm

Kudo

[46]

(2003)

32

(AgIn)

x

Zn

2(1–

x

)

S

2

solid solution (Pt‐loaded)

An apparent quantum yield of 20% for H

2

evolution at 420 nm

Kudo

[47]

(2004)

33

GaN:ZnO solid solutions

Overall water splitting on (Ga

1–

x

Zn

x

)(N

1–

x

O

x

) solid solution photocatalyst

Domen

[48

–

50]

(2005)

34

CdS–Au–TiO

2

nanojunctions

All‐solid‐state Z‐scheme system

Tada

[51]

(2006)

35

Mesoporous anatase hollow microspheres

Fabrication of hollow TiO

2

microspheres by chemically induced self‐transformation

Yu

[52

,

53]

(2006)

36

BiOX powders

First report on the BiOX (X = Cl, Br, I) photocatalysts

Zhang

[54]

(2008)

37

TiO

2

–graphene composites

The photocatalytic reduction of graphene oxide using TiO

2

Kamat

[55]

(2008)

38

Au–TiO

2

The concept of plasmonic photocatalysts

Tatsuma

[56]

(2005)

39

TiO

2

nanosheets

The fabrication of anatase TiO

2

crystals predominantly exposed with (101) facets

Lu and Qiao

[57]

(2008)

40

MoS

2

/CdS

The utilization of MoS

2

as H

2

‐evolution cocatalysts

Li

[58]

(2008)

41

g‐C

3

N

4

First report on the g‐C

3

N

4

photocatalyst

Wang

[59]

(2009)

42

Pt–PdS/CdS

The highest quantum efficiency of H

2

generation (93%) by loading Pt and PdS as dual cocatalysts on CdS

Li

[60]

(2009)

43

CdS–ZnO

Demonstrated ZnO/CdS heterostructures based on the Z‐scheme mechanism

Lu and Cheng

[61]

(2009)

44

(Pt/ZrO

2

/TaON)–(Pt/WO

3

)

The highest quantum yield of 6.3% for Z‐scheme systems

Domen

[62]

(2010)

45

CdS–NiS

The utilization of NiS as H

2

‐evolution cocatalysts

Xu

[63]

(2010)

46

Cu and Pt co‐loaded TiO

2

nanotube arrays

Photocatalytic conversion of CO

2

and water vapor into hydrocarbon fuels

Grimes

[64]

(2009)

47

Ag

3

PO

4

First report on the Ag

3

PO

4

photocatalyst

Ye

[65]

(2010)

48

Hollow TiO

2

microspheres and photocatalytic selectivity

Tunable photocatalytic selectivity by using exposed (001) facets and designed surface chemistry

Yu

[66]

(2010)

49

TiO

2

nanocrystals

First report on black hydrogenated TiO

2

Chen

[67]

(2011)

50

CdS cluster/graphene composite

Photocatalytic H

2

evolution over graphene‐based composite semiconductor

Yu

[68]

(2011)

51

BiVO

4

–(Ru/SrTiO

3

:Rh)

Construction of all‐solid‐state Z‐scheme systems by using rGO as a solid‐state electron mediator

Amal

[69]

(2011)

52

Cu(OH)

2

cluster modified TiO

2

Utilization of Cu(OH)

2

as H

2

‐evolution cocatalysts

Yu

[70]

(2011)

53

Ni(OH)

2

cluster modified TiO

2

Enhanced photocatalytic H

2

production activity of TiO

2

by Ni(OH)

2

cluster modification

Yu

[71]

(2011)

54

CuS/ZnS porous nanosheet photocatalysts

A visible light‐induced interfacial charge transfer (IFCT) mechanism for enhanced photocatalysis

Yu

[72]

(2011)

55

Ultrafine Pt‐loaded TiO

2

single crystals

CO

2

photoreduction to CH

4

with a super high yield of 1361 μmol g‐cat

−1

 h

−1

Biswas

[73]

(2012)

56

(MoS

2

 + graphene)/TiO

2

composites

2D–2D hybrid of MoS

2

and graphene as dual‐electron cocatalysts for H

2

evolution

Yu

[74]

(2012)

57

rGO–Zn

x

Cd

1–

x

S nanocomposites

Noble metal‐free photocatalysts for enhanced solar photocatalytic H

2

Production

Yu

[75]

(2012)

58

Direct Z‐scheme g‐C

3

N

4

/TiO

2

Enhanced photocatalytic performance of direct Z‐scheme g‐C

3

N

4

/TiO

2

photocatalyst for decomposition of formaldehyde in air

Yu

[76]

(2013)

59

Surface heterojunction

Surface heterojunction within single TiO

2

particles

Yu

[77]

(2014)

60

Ternary NiS/Zn

x

Cd

1–

x

S/rGO nanocomposites

Co‐loading of noble metal‐free

reduced graphite oxide

(

rGO

) and NiS (reduction and oxidation cocatalysts) on Zn

x

Cd

1–

x

S

Yu

[78]

(2014)

61

Carbon nanodot–C

3

N

4

Overall water splitting by the metal‐free photocatalysts

Kang

[79]

(2015)

62

Hierarchical CdS–WO

3

heterostructure

A direct hierarchical Z‐scheme CdS–WO

3

heterostructure for photocatalytic CO

2

reduction to CH

4

Yu

[80]

(2015)

63

MS

2

–CdS (M = W or Mo) nanohybrids

Wurtzite CdS nanocrystals hybridized with single‐layer MS

2

nanosheets for efficient photocatalytic H

2

evolution

Zhang

[81]

(2015)

64

1D

poly(diphenylbutadiyne)

(

PDPB

) nanostructures

Metal‐free PDPB nanofibers for photocatalytic degradation of methyl orange and phenol

Remita

[82]

(2015)

65

Graphene‐g‐C

3

N

4

nanocomposites

Sandwich‐like graphene‐g‐C

3

N

4

hybrid nanostructures for enhanced visible light photoreduction of CO

2

to CH

4

Chai

[83]

(2015)

66

g‐C

3

N

4

/ZnO binary nanocomposite

A direct Z‐scheme g‐C

3

N

4

/ZnO system for photocatalytic reduction of CO

2

to CH

3

OH

Peng

[84]

(2015)

67

Ultrathin g‐C

3

N

4

nanosheet assemblies

Hierarchical amine‐functionalized ultrathin g‐C

3

N

4

nanosheet assemblies for photoreduction of CO

2

to CH

4

and CH

3

OH

Yu

[85]

(2016)

68

Hybrid film of g‐C

3

N

4

and Ti

3

C

2

nanosheets

Ti

3

C

2

(with MXene phase) nanosheets as cocatalyst for photocatalytic O

2

evolution

Qiao

[86]

(2016)

69

SrTiO

3

:La, Rh, and BiVO

4

:Mo powders embedded into an Au layer

Z‐scheme systems for pure water (pH 6.8) splitting with a solar‐to‐hydrogen energy conversion efficiency of 1.1% and an apparent quantum yield of over 30% at 419 nm

Domen

[87]

(2016)

70

FeCoW oxyhydroxides

Report on the lowest overpotential (191 mV) for the oxygen evolution reaction

Sargent and Vojvodic

[88]

(2016)

71

Hollow cobalt‐based bimetallic sulfide

Hollow Zn

0.30

Co

2.70

S

4

with higher electrocatalytic HER activity than most noble metal‐free electrocatalysts

Zou

[89]

(2016)

72

GaAs/InGaP/TiO

2

/Ni photoanode, Pd/C/Ti mesh cathode

Solar‐driven reduction of 1 atm of CO

2

to formate at 10% energy conversion efficiency

Lewis

[90]

(2016)

73

Hierarchical g‐C

3

N

4

nanostructures

Hierarchical porous O‐doped g‐C

3

N

4

nanotubes for photocatalytic CO

2

reduction to CH

3

OH

Yu

[91]

(2017)

74

Au/La

2

Ti

2

O

7

sensitized with black phosphorus

An efficient broadband solar‐responsive photocatalyst for H

2

production

Majima

[92]

(2017)

75

Black phosphorus nanosheets

Visible light photocatalytic H

2

evolution of black phosphorus nanosheets

Yang and Du

[93]

(2017)

76

Ti

3

C

2

/CdS nanocomposites

Ti

3

C

2

MXene cocatalysts significantly boosting photocatalytic H

2

production activity over CdS

Qiao

[94]

(2017)

77

Ni/CdS nanoparticles

Photocatalytic H

2

evolution by dehydrogenation of 2‐propanol

Xiao

[95]

(2016)

78

In‐plane (Cring)–g‐C

3

N

4

heterostructure

2D g‐C

3

N

4

‐based in‐plane heterostructures for efficient photocatalytic H

2

production

Liu and Wei

[96]

(2017)

79

W

18

O

49

/g‐C

3

N

4

heterostructure

First report on the non‐metal plasmonic W

18

O

49

Dong

[97]

(2017)

80

Defective TiO

2

Photocatalytic NH

3

production from water and N

2

at atmospheric pressure and room temperature over surface oxygen vacancies of TiO

2

Shiraishi

[98]

(2017)

81

Defective one‐unit‐cell ZnIn

2

S

4

atomic layers

Defect‐mediated electron–hole separation in one‐unit‐cell ZnIn

2

S

4

layers for boosted solar‐driven CO

2

reduction

Xie

[99]

(2017)

82

CsPbBr

3

QD/GO

A CsPbBr

3

perovskite quantum dot/graphene oxide composite for photocatalytic CO

2

reduction

Kuang

[100]

(2017)

83

Methylammonium lead iodide (MAPbI

3

)

Photocatalytic H

2

generation from hydriodic acid using methylammonium lead iodide

Nam

[101]

(2017)

84

Black phosphorus/g‐C

3

N

4

Metal‐free photocatalyst for H

2

evolution in visible to near‐infrared region

Majima

[102]

(2017)

85

NiS/Ni/g‐C

3

N

4

Constructing Ni interface layers in the g‐C

3

N

4

nanosheets/amorphous NiS heterojunctions for efficient photocatalytic H

2

generation

Li

[103]

(2017)

86

(Au/CoO

x

–BiVO

4

)/(ZrO

2

/TaON)

Photocatalytic Z‐scheme overall water splitting system with an apparent quantum efficiency of 10.3% at 420 nm

Zhang and Li

[104]

(2018)

87

β‐ketoenamine COFs

Diacetylene‐functionalized covalent organic framework (COF) for photocatalytic hydrogen generation

Thomas

[105]

(2018)

88

High‐symmetry Cu

2

O photocatalyst particle

Demonstrating that the holes and electrons are transferred to the illuminated and shadow regions of a single Cu

2

O particle, respectively

Li

[106]

(2018)

89

Ni

3

C/CdS

Ni

3

C nanoparticles as a new cocatalyst for photocatalytic H

2

evolution

Li

[107]

(2018)

90

P‐doped CdS

P‐doped CdS for photocatalytic water splitting without sacrificial agents

Chen

[108]

(2018)

91

Graphdiyne/TiO

2

nanofibers

Graphdiyne as a new photocatalytic CO

2

reduction cocatalyst

Yu

[109]

(2019)

92

WO

3

/g‐C

3

N

4

Firstly proposing the concept of step‐scheme (S‐scheme) heterojunction

Yu

[110]

(2019)

93

TiO

2

/CdS

The direct Z‐scheme charge carrier migration pathway firstly confirmed by

in situ

irradiated X‐ray photoelectron spectroscopy

Yu

[111]

(2019)

94

C

3

N

5

First report of a C

3

N

5

photocatalyst

Kumar, and Shankar

[112]

(2019)

95

Atomically thin CuIn

5

S

8

layers

Selective visible light‐driven photocatalytic CO

2

reduction to CH

4

mediated by atomically thin CuIn

5

S

8

layers

Xie

[113]

(2019)

96

Single‐atom Cu/TiO

2

photocatalysts

Reversible and cooperative photoactivation

Hyeon, Kim, and Nam

[114]

(2019)

97

Resorcinol–formaldehyde resins

Metal‐free semiconductor photocatalysts for solar‐to‐hydrogen peroxide energy conversion

Shiraishi

[115]

(2019)

98

Y

2

Ti

2

O

5

S

2

Oxysulfide photocatalyst for visible light‐driven overall water splitting

Domen

[116]

(2019)

99

Al‐doped SrTiO

3

Achieving the upper limit of quantum efficiency for overall water splitting

Domen

[117]

(2020)

In 2001, the doping of N into TiO2 (by replacing O in the lattice) [37] was first reported in the journal Science. The resulting TiO2−xNx material showed high photocatalytic activity under the visible light (λ < 500 nm). The publication of this work started the research of the second‐generation TiO2 photocatalysts. Subsequently, the visible photocatalytic properties of S‐, F‐, and C‐doped TiO2 have been reported successively [39, 40]. Although these studies have greatly improved the light absorption of photocatalytic materials in the visible light region, the introduced modifiers, N or C atoms, are easy to disintegrate from the crystal lattice under the light irradiation. Therefore, the stability of these modified visible light photocatalytic materials is poor, and the reusability in practical application is limited to a certain extent [118].

In 2008, Yang and Qiao successfully synthesized TiO2 nanoflakes with high exposure ratio of (001) crystal facets by using hydrogen fluride (HF) as crystal surface control agent [57]. Further studies showed that TiO2 hollow nanospheres with high exposure ratio of the (001) crystal facets and surface fluorination had better photocatalytic degradation activity and good selectivity for methyl orange [66]. More interestingly, Yu et al. proposed the concept of surface (crystal surface) heterojunction [77]. By optimizing the ratio of different exposed crystal facets of TiO2, the best photocatalytic activity for CO2 reduction to CH4 was achieved [77].

In 2003, Zhang and Yu constructed the hierarchical porous TiO2 microspheres and confirmed that the hierarchical mesoporous and macroporous structures can effectively increase the photocatalytic degradation activity of n‐pentane in the gas phase [44, 45]. Meanwhile, Yu et al. synthesized the mesoporous hollow TiO2 microspheres by using a chemical‐induced self‐transformation strategy, whose photocatalytic activity was double that of P25 [53].

In 2011, Chen et al. first developed black TiO2 with disordered surface structure and confirmed its high hydrogen production activity [67]. This study further stimulated the researchers to control the defects and surface structure of the photocatalysts, so as to improve the photocatalytic activity. In addition, various noble metal and non‐noble metal cocatalysts (such as Pt, Cu(OH)2, NiO, MoS2, and graphene) have been widely developed and applied to greatly enhance the H2 production and CO2 reduction activities of TiO2‐based photocatalysts [22, 23, 27, 28, 64, 73, 74]. All in all, as the core photocatalyst, TiO2 modification research and diversified applications will continue in full swing.

In addition to TiO2‐based photocatalysts, the development of non‐TiO2‐based photocatalysts and the exploration of new mechanisms have been the recent focus of photocatalytic research. Since the 1980s, a variety of new non‐TiO2‐based photocatalysts have been found, such as SrTiO3[18, 19], ZnxCd1−xS [26], BiVO4[33, 34], In1−xNixTaO4[35], Ta3N5[41], TaON [42], AgInZn7S9[43], (AgIn)xZn2(1−x)S2[47], (Ga1−xZnx)(N1−xOx) [48–50], BiOX (X = Cl, Br, I) [54], Ag@AgCl [119], g‐C3N4[59, 120], C3N5[112], resorcinol–formaldehyde resins [115], β‐ketoenamine covalent organic frameworks (COFs) [105], Y2Ti2O5S2[116], Ag3PO4[65], etc. There is no doubt that g‐C3N4 has become a dazzling new star in the field of photocatalysis in recent years [120–123]. Importantly, the appearance of graphene, a new type of two‐dimensional (2D) ultrathin and highly conductive material, has injected infinite power into the design and development of new efficient photocatalysts. Various kinds of graphene‐based composite photocatalyst materials are springing up [68, 74, 75, 124–127]. On the other hand, new photocatalytic mechanisms have been studied constantly. Bard first proposed the Z‐scheme photocatalytic mechanism of biomimetic photosynthesis in 1979 [20]. In 2001, Arakawa and coworkers successfully constructed the first Z‐scheme photocatalytic overall water splitting system with I−/IO3− redox pairs, Pt‐loaded rutile TiO2 (H2 production catalyst), and anatase TiO2 (O2 production catalyst) [38]. Domen achieved a quantum efficiency of 6.3% for photocatalytic overall water splitting under monochromatic light irradiation (λ = 420.5 nm), by using Pt/ZrO2/TaON, Pt/WO3, and I−/IO3− as the H2 production photocatalyst, O2 production photocatalyst, and the electron mediator, respectively [62]. More recently, Zhang and Li reported a photocatalytic Z‐scheme overall water splitting system with an apparent quantum efficiency (AQE) of 10.3% at 420 nm using [Fe(CN)6]3−/[Fe(CN)6]4−, Au/CoOx–BiVO4, and ZrO2/TaON as redox mediator, H2‐evolving, and O2‐evolving photocatalysts, respectively, which is so far the Z‐scheme reaction system with the highest quantum efficiency for photocatalytic overall water splitting [104]. At the same time, all‐solid‐state and direct Z‐scheme systems have been successfully developed and applied to photocatalytic decomposition of water and reduction of CO2[51, 69, 80, 84, 111, 128–130]. Moreover, a photoinduced interfacial charge transfer (IFCT) mechanism has been proved to be useful in the design and construction of novel visible light photocatalysts [72]. In particular, recently reported black phosphorus [92, 93], MXene cocatalyst [86, 94], graphdiyne [109], defective one‐unit‐cell ZnIn2S4 atomic layers [99], atomically thin CuIn5S8 layers [113], planar heterojunction [96], and van der Waals heterojunction [131, 132] provide a broader space for the design of 2D semiconductor photocatalysts. In addition, some other efficient hydrogen production systems such as Pt–PdS/CdS [60], non‐noble metal (MoS2/CdS [58], graphene/ZnxCd1−xS [75], NiS/ZnxCd1−xS/graphene [78], Ni3C/CdS [107], CdS–NiS [63], NiS/Ni/g‐C3N4[103], and C3N4–CdS–NiS [133]) as well as metal‐free carbon dots/g‐C3N4[79] have been successfully constructed successively. All in all, the development of a series of non‐TiO2‐based heterojunction photocatalytic materials, new mechanisms, and efficient systems will continue to advance the research in the field of photocatalysis.

1.3 Fundamental Principles of Solar Energy Photocatalysis

1.3.1 Basic Mechanisms for Solar Energy Photocatalysis

So far, four basic mechanisms have been extensively employed to describe the charge carrier generation and migration processes in heterogeneous photocatalysis, namely, inorganic semiconductor photocatalysis (Figure 1.2a), organic semiconductor photocatalysis (Figure 1.2b), surface plasmon resonance (SPR, Figure 1.2c), and IFCT (Figure 1.2d). Among these four basic photocatalytic mechanisms, inorganic semiconductor photocatalysis and organic semiconductor photocatalysis are the most commonly used mechanisms for heterogeneous photocatalysis, and they share the similar principles. Typically, the electrons in the ground‐state valence band (VB) or highest occupied molecular orbital (HOMO) could be photoexcited into the vacant conduction band (CB) or lowest unoccupied molecular orbital (LUMO