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1D Semiconducting Hybrid Nanostructures
In-depth discussion on the physics, chemistry, and engineering beneath the construction of 1D semiconducting hybrid materials
1D Semiconducting Hybrid Nanostructures: Synthesis and Applications in Gas Sensing and Optoelectronics provides breakthrough research developments and trends in a variety of 1D hybrid nanostructures for chemi-resistive gas sensors and optoelectronics applications, including recent investigations and developments regarding the innovative designing approaches, fabrications, and methods used to characterize these hybrid nanostructures. The text also includes the surface and interface properties of 1D hybrid semiconducting nanostructured materials, as well as their optimization for applications in gas sensing and optoelectronics.
This book further addresses the different issues of sensitivity, selectivity, and operating temperature of gas sensors based on hybrid 1D nanostructures. Moreover, it covers the novel and additional functional optoelectronic properties that originate at the interface of 1D semiconducting nanostructures combined with other low dimensional materials.
Some of the specific sample topics covered in this book include:
- Gas sensing and optoelectronic applications of one-dimensional semiconducting hybrid nanostructures, plus synthesis and gas sensing application of 1D semiconducting hybrid nanostructures
- Room temperature gas sensing properties of metal oxide nanowire/graphene hybrid structures and highly sensitive room temperature gas sensors based on organic-inorganic nanofibers
- Synthesis and applications of 1D hybrid tin oxide nanostructures and recent advances in semiconducting nanowires-based hybrid structures for solar application
- Types of semiconducting hybrid nanostructures for optoelectronic devices and hybrid 1D semiconducting ZnO/GaN nanostructures
Thanks to its comprehensive coverage of the subject from highly qualified authors who have significant experience in the field, 1D Semiconducting Hybrid Nanostructures is a must-have reference for senior undergraduate and graduate students, professionals, researchers, in the field of semiconductor physics, materials science, surface science, and chemical engineering.
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Veröffentlichungsjahr: 2022
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Table of Contents
Cover
Title Page
Copyright
Preface
1 One‐Dimensional Semiconducting Hybrid Nanostructure: Gas Sensing and Optoelectronic Applications
1.1 Introduction
1.2 Synthesis of 1D Hybrid Nanostructures
1.3 Applications of 1D Hybrid Nanostructures
1.4 Conclusions
Acknowledgment
References
2 Synthesis and Gas‐Sensing Application of 1D Semiconducting Hybrid Nanostructures
2.1 Introduction
2.2 Noble Metal‐Functionalized 1D Metal Oxide Semiconductors for Gas Sensors
2.3 1D Metal Oxide/Metal Oxide Heterojunctions‐Based Gas Sensors
2.4 Conducting Polymer/1D Metal Oxide Nanocomposites for Gas Sensors
2.5 Hybrid Conducting Polymer/Carbon Nanotube‐Based Gas Sensors
2.6 Conclusion and Future Perspectives
Acknowledgment
References
3 Room‐Temperature Gas‐Sensing Properties of Metal Oxide Nanowire/Graphene Hybrid Structures
3.1 Introduction
3.2 Synthesis of Graphene and Graphene Oxide
3.3 Graphene/Metal Oxide Nanowires Hybrid‐Based Sensors
3.4 Conclusion
References
4 Highly Sensitive Room‐Temperature Gas Sensors Based on Organic–Inorganic Nanofibers
4.1 Introduction
4.2 Classification of Nanofibers for Gas‐Sensing Application
4.3 Different Configurations of Gas Sensors
4.4 Synthesis of NFs
4.5 Role of Physicochemical Properties of Nanofibers in Gas Sensing
4.6 Enhancement of Characteristics of Nanofibers‐Based Sensor Performance
4.7 Recent Trends
4.8 Conclusion and Future Perspectives
Acknowledgment
References
5 1D Hybrid Tin Oxide Nanostructures: Synthesis and Applications
5.1 Main Features of 1D Materials
5.2 Synthesis of 1D SnO, Sn
3
O
4
, and SnO
2
Materials
5.3 Tin‐Based Hybrid Nanostructures
5.4 Gas‐Sensing Performance of 1D Tin Oxide‐Based Hybrid Nanostructures
5.5 Photo(Electro)Catalytic Application of 1D Tin Oxide‐Based Heterostructures and Doped Materials
5.6 Other Applications of 1D Tin Oxides
5.7 Final Considerations and Future Outlook
Acknowledgments
References
6 Recent Advances in Semiconducting Nanowires‐Based Hybrid Structures for Solar Cell Application
6.1 Introduction
6.2 Semiconductor Materials
6.3 Semiconductor Nanowires Synthesis
6.4 Applications of Semiconductors in Solar Cells
6.5 Conclusion and Future Perspectives
References
7 Introduction and Types of Semiconducting Hybrid Nanostructures for Optoelectronic Devices
7.1 Introduction
7.2 Synthesis of Nanostructured Materials
7.3 Applications of ZnO–Graphene Heterostructure for Photon Detection
7.4 Conclusion and Summary
References
8 One‐Dimensional Si Nanostructure‐Based Hybrid Systems: Surface‐Enhanced Raman Spectroscopy and Photodetector Applications
8.1 Introduction
8.2 Si Nanostructures
8.3 Fabrication of 1D Si Nanostructures
8.4 Applications of 1D Si Nanostructures Hybrids in SERS and Photodetectors
8.5 Conclusions
References
9 Hybrid 1D Semiconducting ZnO and GaN Nanostructures for Light‐Emitting Devices
9.1 Introduction About 1D Nanostructures
9.2 Synthesis Methods for the Growth of 1D Nanostructure
9.3 Application of ZnO‐ and GaN‐Based Hybrid 1D Nanostructure for Light‐Emitting Devices
9.4 Conclusion
References
10 Optoelectronic Properties of TiO
2
Nanorods/Au Nanoparticles Heterostructure
10.1 Introduction
10.2 Theory of Electron Transfer
10.3 Experimental
10.4 Results and Discussion
10.5 Conclusions
Acknowledgments
Compliance with Ethical Standards
References
11 2D Materials with 1D Semiconducting Nanostructures for High‐Performance Gas Sensor
11.1 Introduction
11.2 Enhanced Gas‐Sensing Performances of 1D‐Sensing Materials Composited with Different 2D Materials
11.3 Remain Challenges and Possible Effective Ways to Explore High‐Performance Gas Sensor
11.4 Conclusions
Acknowledgments
References
12 Recent Advancement in the Development of Optical Modulators Based on 1D and 2D Materials
12.1 Introduction
12.2 Optical Modulation in Fiber Lasers
12.3 1‐Dimensional Structured Materials
12.4 2D‐Structured Materials
12.5 1D and 2D Material‐Based Saturable Absorbers for Fiber Lasers
12.6 Conclusion, Challenges, and Future Perspectives
References
13 1D and 2D Semiconducting Hybrid Nanostructures for Advanced Photodiodes
13.1 Introduction
13.2 Principle of Photodetector
13.3 Types of Photodetectors
13.4 Applications of Photodetectors
13.5 Device Fabrication Methods
13.6 Device Characterizations
13.7 Current Status of 1D/2D Hybrid Nanostructures Photodetectors
13.8 Conclusion
References
Index
End User License Agreement
List of Tables
Chapter 1
Table 1.1 1D hybrid nanostructures, types, method of synthesis, analyte gas...
Chapter 2
Table 2.1 The gas‐sensing properties of noble metal NPs‐functionalized 1D n...
Table 2.2 Gas sensors based on CNTs/polymer nanocomposites.
Chapter 4
Table 4.1 Survey of NFs‐based nanohybrids for gas‐sensing application.
Table 4.2 Noble metal sensitizers‐doped NFs for gas‐sensing application.
Chapter 12
Table 12.1 Summary of Q‐switched fiber lasers based on 1D materials.
Table 12.2 Summary of mode‐locked fiber lasers based on 1D materials.
Table 12.3 Summary of Q‐switched fiber lasers based on 2D materials.
Table 12.4 Summary of mode‐locked fiber lasers based on 2D materials.
List of Illustrations
Chapter 1
Figure 1.1 SEM image (a) on a plane sapphire wafer, ZnO nanowires, and (b) G...
Figure 1.2 SEM picture of ZnO nanorod (a) upper view and (b) oblique view....
Figure 1.3 (a) Diagrammatic illustration of SnO
2
/NiO‐X CSNWs; (X is the numb...
Figure 1.4 The advancement of Fe
2
O
3
/SnO
2
reaction.
Figure 1.5 (a) Au‐SnO
2
NFs diagrammatic representation; (b) transparency det...
Figure 1.6 (a) Schematic depiction of localized surface plasmon resonance in...
Figure 1.7 (a) SEM picture of a PV unit with yellow and brown artificial dye...
Chapter 2
Figure 2.1 The overview of this chapter.
Figure 2.2 The promising gas sensors based on noble metal‐functionalized 1D ...
Figure 2.3 The gas‐sensing feature of Au‐loaded ZnO/SnO
2
core–shell NRs.
Figure 2.4 The synthetic strategy and gas‐sensing feature of PPy‐coated 1D S...
Figure 2.5 The typical approach to fabricate hybrid polymer/carbon nanotubes...
Figure 2.6 The synthetic process hybrid carboxylated polypyrrole (CPPy) skin...
Chapter 3
Figure 3.1 Response transients for (a) ZnO NWs, (b) pure RGO, (c) 10 wt% ZnO...
Figure 3.2 (a) Dynamic response of Cu
2
O‐NW, RGO‐Cu
2
O, and RGO devices for in...
Figure 3.3 The sensing response curves for the device under different NO
2
co...
Figure 3.4 The sensing response curves for SnO
2
nanowires/RGO‐based sensing ...
Figure 3.5 (a) Response transients for SnO2/RGO nanocomposite‐based gas sens...
Figure 3.6 SEM images of ZnO‐NWs grown (a) with and (b) without using surfac...
Figure 3.7 (a) SEM of RGO/NFs hybrid. Room‐temperature (b) NO
2
and (c) SO
2
r...
Chapter 4
Figure 4.1 Classification of gas sensors based on physicochemical properties...
Figure 4.2 Effect of morphology on (a) energy band bending of hollow and fil...
Figure 4.3 Schematic of sensing mechanism of RGO/SnO
2
NFs for NO
2
(a) in dar...
Figure 4.4 Single‐aligned NF‐based gas sensors, (a, b) TiO
2
: Au NF highly se...
Figure 4.5 (a–d) Schematic of coaxial electrospinning used for on‐chip fabri...
Figure 4.6 (a–c) Trends in the NFs‐based wearable electronics, showing use o...
Chapter 5
Figure 5.1 Schematic representation of synthesis by the electrospinning meth...
Figure 5.2 (a)
Scanning electron microscope
(
SEM
) and (b)
Transmission elect
...
Figure 5.3 (a) SEM, (b)
X‐ray energy dispersive spectroscopy
(
EDS
)/TEM...
Figure 5.4 TEM images of (a) Pd‐ and (b) Pt‐functionalized SnO
2
nanowires. (...
Figure 5.5 (a) TEM image and elemental mapping from EDS analysis (inset) of ...
Chapter 6
Figure 6.1 Total number of publications in the last 15 years on nanowire as ...
Figure 6.2 Nanowires for solar cell application.
Figure 6.3 (a) p‐Type and (b) n‐type semiconductors.
Figure 6.4 Schematic representation of a simple photovoltaic cell.
Figure 6.5 (a, b) In flat hybrid devices, the formation of exciton (dots), a...
Figure 6.6 Electron transport channels and light propagation paths in variou...
Figure 6.7 Schematics of the fundamental architectures of HSCs based on inor...
Figure 6.8 (a) SEM images of the ZnO NW nanoforest with a slanted perspectiv...
Figure 6.9 The catalysts' formation paths, which include a network of corner...
Figure 6.10 FE‐SEM image of the TiO
2
NWs fabricated by the process of two hy...
Figure 6.11 (a–d) TEM morphological image of the ZnS nanowire, and (e, f) ED...
Figure 6.12 (a) FE‐SEM image of CdS NWs, (b, c) SEM image of the structure o...
Figure 6.13 (a) SEM images of NaNbO
3
nanowires and (b) SEM images of Pt/NaNb...
Figure 6.14 A schematic of c‐Si solar cell structure.
Figure 6.15 One of the completed modules in front of the R2R coater.
Chapter 7
Figure 7.1 (a) Van der Waals hybrid structures.. (b) Overview of the 2D ...
Figure 7.2 (a–f) SEM images of ZnO nanowires/nanorods grown by CVD system. (...
Figure 7.3 (a, b) 1D ZnO nanowires. (c, d) Enlarged FESEM images of ZnO/RGO ...
Figure 7.4 (a, b) Typical SEM picture of ZnO and ZnO–MoS
2
.. (c, j) pH‐me...
Figure 7.5 (a) ZnO NW/graphene foam‐based UV photon detector. (b) Cyclic pho...
Chapter 8
Figure 8.1 (a) VLS mechanism for the growth of SiNWs proposed by Wagner and ...
Figure 8.2 (a) SEM images for polystyrene nanosphere lithography (a) monolay...
Figure 8.3 Schematic diagram illustrating localized surface plasmon at Au/ai...
Figure 8.4 Scanning electron micrographs of (a and b) 45° tilted view SiNPLs...
Figure 8.5 (a)
Finite difference time domain
(
FDTD
) simulated plasmonic hot ...
Figure 8.6 (a) Scanning electron micrograph for AgNPs formed on SiNPLs.(...
Figure 8.7 (a) SEM images of SiNPLs. Cross‐sectional image is shown in inset...
Chapter 9
Figure 9.1 Schematic diagram of LEDs fabricated by hydrothermal method based...
Figure 9.2 Schematic representation of LED device (Gd‐doped ZnO NTs/p‐GaN) p...
Figure 9.3 (a) The cross‐sectional SEM image of ZnO NRs/p‐GaN film heterostr...
Figure 9.4 (a) Current–voltage characteristics of Gd‐doped ZnO NTs/p‐GaN het...
Figure 9.5 (a) Schematic diagram of graphene‐decorated LED device based on Z...
Figure 9.6 The EL curve of the graphene‐incorporated n‐ZnO NWs/p‐GaN vertica...
Chapter 10
Figure 10.1 (a) Band diagram of TiO
2
NR/AuNP, (b) schematic electron transfer...
Figure 10.2 (a) FESEM of TiO
2
NR, (b) FESEM of TiO
2
NR/AuNP, (c) cross section...
Figure 10.3 X‐ray diffraction pattern for TiO
2
NR and TiO
2
NR/AuNP.
Figure 10.4 (a) Tauc plot for TiO
2
NR with concentration variation, (b) Tauc ...
Figure 10.5 Quantum mechanical analysis for (a) TiO
2
NR and (b) TiO
2
NR/AuNP i...
Figure 10.6 Amperometric (current–time) analysis for TiO
2
NR and TiO
2
NR/AuNP....
Chapter 11
Figure 11.1 SEM images of graphene (a and b) and ZnO nanowires composited wi...
Figure 11.2 SEM image of graphene oxide (a) and the MoO
3
nanoribbons composi...
Figure 11.3 The sketch (a) and the optical micrograph image (b) of the assem...
Figure 11.4 FESEM and TEM images of (a) ZnO, (b, d) ZnO/WS
2
1×, (c, e) ZnO/W...
Figure 11.5 SEM images (a and b) and TEM image (c) of the ZnO‐decorated Zn
2
S...
Figure 11.6 SEM images of NiO‐decorated WO
3
with their proportions (wt%) bei...
Figure 11.7 (a) SEM image, (b) TEM image, and (c) high‐resolution HAADF‐STEM...
Figure 11.8 (a–d) SEM images, (e) TEM image, and (f–h) corresponding element...
Chapter 12
Figure 12.1 1D materials in the form of different structures, including nano...
Figure 12.2 Example of 2D‐structured materials: monoelements [54–56], chalco...
Figure 12.3 Possible arrangements of 1D and 2D materials as SAs. (a) Sandwic...
Figure 12.4 Q‐switching fiber lasers with various 1D SAs. (a–e) Ag. (a) Ag s...
Figure 12.5 Mode‐locked fiber lasers with various 1D SAs. (a–c) CNTs‐PCF. (a...
Figure 12.6 Q‐switched fiber lasers with various 2D SAs. (a–c) Antimonene. (...
Figure 12.7 Mode‐locked fiber lasers with various 2D SAs. (a–c) Bismuthene. ...
Chapter 13
Figure 13.1 (a) A high magnification SEM image of 1D ZC with a smooth outer ...
Figure 13.2 Photodiode working principle.
Figure 13.3 Schematic diagram of PIN photodiode.
Figure 13.4 Schematic diagram of avalanche photodiode.
Figure 13.5 Typical structure of phototransistor.
Figure 13.6 Application of PDs in various spectral ranges.
Figure 13.7 Experimental setup of vapor phase transport deposition of C‐ZnO ...
Figure 13.8 Schematic diagram shows the preparation of BN/GO composite layer...
Figure 13.9 Schematic diagram of E‐beam evaporation technique used to deposi...
Figure 13.10 (a) DC sputtering system used for deposition of metal electrode...
Figure 13.11 Spin coater.
Figure 13.12 (a) Keithley source meter 2410 for
I
–
V
characterization and (b)...
Figure 13.13 (a) Temporal measurement setup of graphene in planar structure ...
Figure 13.14 Photocurrent responses of a 1D GaTe nanowire (blue) and 2D GaTe...
Figure 13.15 (a) Responsivity and EQE (inset) of BN/GO composite photodetect...
Figure 13.16 Temporal measurement of BN/GO composite layer.
Figure 13.17 (a) Illustration of a fully printed flexible photodetector base...
Figure 13.18 (a) TEM image of 2D‐layered MnPSe
3
. (b)
I
ds
−
V
ds
characteristics...
Figure 13.19 (a) Te NWs SEM image. The matching enlarged photos of the singl...
Guide
Cover
Table of Contents
Title Page
Copyright
Preface
Begin Reading
Index
End User License Agreement
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1D Semiconducting Hybrid Nanostructures
Synthesis and Applications in Gas Sensing and Optoelectronics
Edited by Arvind Kumar, Dinesh K. Aswal, and Nirav Joshi
Editors
Dr. Arvind KumarChaman Lal (P.G.) CollegeDepartment of PhysicsChaman Lal MahadidhyalayaHaridwarIndia
Dr. Dinesh K. AswalCSIR‐National Physical LaboratoryNew DelhiIndia
Dr. Nirav JoshiUniversity of Sao PaoloSao Caro Institute of PhysicsSao PaoloBrazil
Cover Image: © Inkoly/Shutterstock
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.
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© 2023 Wiley‐VCH GmbH, Boschstraße 12, 69469 Weinheim, Germany
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Preface
In recent years, the progress in the gas‐sensing and optoelectronic fields has swiftly escalated because of their exceeding utilization in applications having high technological throughputs. Avant‐garde gas sensors are now commercially available as a result of emerging electronic technologies backed up by novel and innovative ideas, which do not only offer superior advancements like increased portability and size miniaturization but also feed on minimized power while offering prolonged durability. In such a case, one‐dimensional (1D) semiconducting nanostructures, such as nanowires, nanopillars, and nanorods, have shown promising potential for scientific and technological fields in many ways. These structures offer several unique advantages, such as high specific surface area, smaller diameter, efficient charge transport, and excellent light trapping capability. It also explores the functional optoelectronic features that emerged at the interface when 1D semiconducting nanostructures were coupled with other low‐dimensional materials. The topics discussed in the book are critical to a wide spectrum of modern and new nanotechnologies used or to be used in most industries, academics, healthcare, food, the environment, energy, and research institutes, and thus have a significant impact on our society. This book primarily focuses on providing breakthrough research developments and trends in a variety of 1D hybrid nanostructures for chemiresistive gas‐sensing and optoelectronics applications. Further, it highlights the applicability of the developed sensors using 1D hybrid nanostructures in a wide range of modern nanotools and nanodevices deployed in the electronic, healthcare, biomolecules detection, food, pharmaceutical, and medical industries that have a significant impact on our society.
The field of gas sensors and optoelectronic devices is indeed experiencing fast and consistent growth. There is an incredibly wide range of materials, and almost all known materials, including metal oxides, polymers, dichalcogenides, and ferrites, can be utilized in designing gas sensors and optoelectronic devices. However, the desired application‐oriented selection of these materials is a challenging and multivariate task. While taking this situation into account, a comprehensive analysis of the available sensing materials with respect to their design and development strategies that are compatible with modern semiconductor fabrication technology has been concluded in this book. Besides, superior and/or additional electronic, mechanical, electrical, and thermal properties offered by these 1D hybrid nanostructured materials in contrast to pristine 1D nanostructures are also discussed herein. Close attention is given to the problems associated with the stability, selectivity, and functionalizing of these nanostructures. This book consolidates up‐to‐date information on every aspect of these 1D hybrid nanostructured materials, including their sensing mechanisms, device performance, and state‐of‐the‐art applications, covering the entire spectrum of the most recent literature citations, current market, and patents in a very detailed manner. In a nutshell, this book is an effort made in the quest to unravel the recent advances in the gas‐sensing and optoelectronic worlds, while simultaneously suggesting potential solutions to tackle the limitations in this field. This book will be a valuable and accessible guide to the material scientists and researchers from universities and national laboratories working in this phenomenal and exciting field of functional materials.
1One‐Dimensional Semiconducting Hybrid Nanostructure: Gas Sensing and Optoelectronic Applications
Jyoti Rawat, Himani Sharma, and Charu Dwivedi
Doon University, School of Physical Sciences, Department of Chemistry, Kedarpuram Dehradun, Uttarakhand, 248001, India
1.1 Introduction
The study and manipulation of matter on the nanoscopic scale is known as nanotechnology. It involves nanoparticles within the size range of 100 nm [1]. The nanomaterial comprises two‐dimensional (2D) nanofilms, one‐dimensional (1D) nanowires (NWs), and zero‐dimensional (0D) nanoparticles [1]. It is widely acknowledged that 1D nanomaterials are quintessential method for investigating a wide range of unique systems at the nanoscale as well as to study the size and dimensional dependency of their functional properties [2]. They are expected to play a key role as both interconnect and fundamental components in nanoscale, optoelectronic, electrochemical, and electromechanical devices. 1D semiconductor nanostructures can be systematically and consistently manufactured in a single‐crystalline form with precise control over their chemical composition, diameter, length, and doping level [3, 4]. Nanostructures have made it possible to develop a wide range of prototype devices and integration methodologies [5].
Hybrid nanostructures are made up of at least two unique elements, both of which have as minimum as 1D nanometer scale [6]. Hybrid nanostructures have the ability to combine the benefits of distinct components while overcoming their flaws, resulting in increased efficiency in certain applications or possibly the generation of unique characteristics and/or functions [7]. The shape, crystalline form, exposed facet, spatial organization, component distribution, and interface between components all contribute to the features and functionality of a hybrid nanostructure [8, 9]. As a result, coherent design and controlled manufacturing of hybrid nanostructures are vital for optimizing material performance in specialized applications as well as improving our knowledge of key framework interactions [10].
In general, there are two types of synthetic approaches for constructing 1D nanostructures: top‐down and bottom‐up. The top‐down technique necessitates horizontal sequencing of bulk materials using either subtractive or additive procedures in order to make nanosized structures [11]. Several technologies, such as gas‐phase condensation and wet ball milling, are employed to produce nanostructures utilizing a top‐down approach [12]. Although the top‐down method has been crucial in the fabrication of nanostructures, it has various disadvantages, including the formation of defects in treated materials, high prices, the necessity for high‐surface‐finish materials, and longer etching durations. Nanostructures are also built from single atoms or molecules in a bottom‐up manner. During the construction of desirable nanostructures (2–10 nm in size range), regulated segregation of atoms or molecules occurs [13]. Some of the technologies used in the bottom‐up approach are molecular beam epitaxy (MBE), chemical vapor deposition (CVD), sol–gel technique, laser pyrolysis, metal–organic decomposition, self‐assembly processes, and wet synthesis [14].
The application of 1D hybrid nanostructure is also being explored in gas sensing and optoelectronic devices. Regulated development of carbon nanotube (CNT) arrays may be used to fabricate electrical and optoelectronic devices such as field‐effect transistors (FETs), photodetectors, and light‐emitting diodes (LEDs) for applicability in optoelectronics of 1D nanostructures LED [15, 16]. Y. Zhao et al. explain current advancement on the construction of organic 1D nanostructures and their distinctive optical and electronic properties, along with their use as basic components in optoelectronic functions and devices such as tunable emission, multicolor emission, optical waveguides, lasing, and modulators. The design and manufacturing techniques of structured 1D nanostructures and their possible implementations in optoelectronic devices such as photovoltaic (PV) cells and switches, and the synthesis of 1D organic nanostructures utilizing a range of organic functional materials spanning from polymers to small molecules, are also documented in the literature [17]. Type II antimonide‐based superlattices in 1D, for instance, can be employed in infrared photon detectors for implementations in electronics, sensing, biosciences, and plasmonics [18, 19].
This chapter describes 1D hybrid nanostructure such as nanotube, NW, and nanotube and their unique properties. The method of fabrication for such nanostructures is also discussed in brief. Furthermore, this chapter also sheds light on the application of 1D nanostructure in the field of gas sensing and optoelectronic devices.
1.2 Synthesis of 1D Hybrid Nanostructures
1.2.1 Top‐Down Approach
The top‐down strategy necessitates horizontal sequencing of bulk materials, using either subtractive or additional processes, to build nanosized morphology [20]. Wet ball milling, gas‐phase condensation, and lithography as well as other top‐down strategies have been employed by researcher to fabricate nanostructures [21]. The most cost‐efficient methods for mass‐producing nanomaterials are mechanical techniques. Wet ball milling appears to be the most fundamental of all. Wet ball milling produces nanomaterials by transmitting kinetic energy from a grinding medium to a material being reduced [21].
Chen et al. employed wet ball milling method to produce hexagonal boron nitride powder which are extremely noncrystalline or amorphous nanoparticles. Boron nitride nanotubes (BNNTs) and nanostructures similar to the bamboo‐shaped BN have been developed [22]. When vaporized materials collide with inert gas molecules in the gaseous phase, they dissipate kinetic energy and condense in the form of nanoscopic crystals which can be accumulated on the substrate as an extremely fine powder [23]. Chepkasov et al. reported an experimental investigation of copper nanoparticles condensation from the gas phase, as well as molecular dynamic modeling of a system with 8500 typical copper atoms. The digital model was established to accurately represent the mechanism of vaporization as well as condensation in significant studies. Lithography is a more adaptable and simple approach for generating self‐assembled 1D nanostructures on various substrates [24]. Lithography is also a quick and efficient method of surface mapping that is applicable for a large variety of substrates. Lithography refers to a variety of surface processing techniques that include projecting a pattern from a photomask onto a substrate's surface, allowing many duplicates to be created from a single exposure [25]. To complement lithographic techniques for the fabrication of 1D semiconductor nanostructures, several other lithographic techniques such as extreme ultraviolet (EUV) and X‐ray lithography (XRL) are being developed [25]. XRL has been extensively explored using radiations in the wavelength range of 0.1–10 nm, as this narrow wavelength range was deemed promising for high‐resolution applications [26]. Despite this, quality imaging UV lithography with a 13.5 nm wavelength irradiation is insufficient [27]. However, considering EUV sources have restricted power, enhancing the sensitivity of resists while maintaining design integrity and consistency is a crucial problem for addressing high‐volume production throughput demands [27].
1.2.2 Bottom‐Up Approach
Bottom‐up approach have proven to be advantageous over the top‐down method as they stands to benefit the preparation of self‐assembled nanostructures that exhibit distinctive interdisciplinary characteristics which are distinguishable from the characteristics demonstrated by the independent constructing constituent [28]. CVD process, sol–gel method, MBE process, molecular self‐assembly (MSA) process, and wet synthesis are some ways utilized in the bottom‐up approach. The method which is broadly used in the semiconductor industrial field for the deposition of thin layers in various substances is CVD [29]. The subjection of the surface to more than one unstable precursors is involved in this process. The reactant is decomposed by the precursors, which interact with it to produce the desirable deposition. In this method, volatilized precursors at the beginning are adsorbed on a surface at a high temperature, which subsequently interact with one another or disintegrate to form crystals [29]. MBE is another method of physical evaporation that does not require any chemical reactions. MBE varies from conventional epitaxy systems because it depends on a simple physical evaporation process rather than chemical interactions. The notion of vacuum evaporation is used in this process, in which hot molecules and atomic rays collide directly with a hot substrate under ultrahigh vacuum conditions [30, 31]. The MBE process has the benefit of operating at a lower temperature than vapor‐phase epitaxy. The MSA method excels in producing nanoparticles in the 1–100 nm range [32]. Critical characteristics like distinct geometry and precise interactions between the basic units must be taken into account when creating complex nanostructures utilizing the MSA method. MSA is a noncovalent binding process in which atoms and molecules assemble in a stable and distinct nanophase [33]. Several 1D TiO2 nanostructures (such as nanorods, NWs, nanotubes, and nanobelts) have been produced for optoelectronic and gas sensor applications throughout, which will be briefly reviewed in the next section (Table 1.1) [43]. The sol–gel method entails merging scattered solid nanoparticles (sols with diameters ranging from 1 to 100 nm) in a homogenous liquid medium and aggregating them to form a coherent three‐dimensional (3D) structure in the liquid phase with pore dimensions in the sub‐micrometer range [44].
Table 1.1 1D hybrid nanostructures, types, method of synthesis, analyte gas molecules, and detection limit.
Methods of syntheses
1D nanostructures type
Analyte gas
Detection limit
References
Hydrothermal
ZnO nanowire
H
2
S
5 ppb
[34]
Electrospinning
SnO
2
BNNT
NO
2
250 ppb
[35]
Electrochemical anodization
TiO
2
nanotube
Ethanol
100 ppm
[36]
Electrodeposition
CuO nanowire
H
2
S
2.5 ppb
[37]
Solvothermal
ZnO nanotube
NO
2
500 ppm
[38]
Oxidation
Fe
2
O
3
nanowire
NH
3
0.95 ppm
[39]
Hydrothermal
TiO
2
nanoparticles
Acetone
500 ppb
[40]
Sol–hydrothermal
Ag‐In
2
O
3
nanorod
H
2
S
0.005 ppm
[41]
Electrospinning
In
2
O
3
/reduced graphene oxide nanofiber
NH
3
44 ppb
[42]
1.2.2.1 Nanotubes
CNTs were found soon after fullerenes were successfully synthesized in one experiment. CNTs have been a subject of investigation since their discovery in 1991, owing to their distinctive structural qualities and properties, as well as their potential technological applications [38]. They resemble a cylinder constructed of a graphite sheet (hexagonal carbon lattice). Nanotubes exhibit a variety of electrical, structural, and thermal properties that vary depending on length, diameter, and chirality or twist of the nanotube [45]. To further the interest, nanotubes can have multiple walls (MWNTs) cylinders inside cylinders in addition to a single cylindrical wall (SWNTs) [46]. Sen et al. pyrolyzed adequate components to create boron carbide nitride (B–C–N) and C–N nanotubes. When aza‐aromatics, like pyridine, are pyrolyzed over cobalt catalysts, CN nanotubes are produced. Thermal decomposition of the 1 : 1 addition compound of BH3 with (CH3)3N yields B–C–N nanotubes. C33N is believed to be the usual composition of C–N nanotubes [46]. Unusual structural morphologies, such as bamboo or nested‐cone‐shaped cross sections, and others with unique morphologies, such as coiled nanotubes, are commonly observed in doped nanotubes. The B–C–N nanotubes composition changes depending on their mode of synthesis. Moreover, single‐walled nanotubes (SWNTs) are the most common product in terms of diameter [47, 48].
1.2.2.2 Nanowires
Over the last years, a broad range of physicochemical methods have been reported the fabrication of semiconducting NWs [49]. These strategies might be classified using both bottoms‐up and top‐down approaches [50]. To create NWs, the physical process relies on cutting bulk single‐crystalline materials (such as Si, Ge, and GaAs) with high‐energy plasma species [51, 52]. Since Wagner and associates created Au‐catalyzed Si micro‐whiskers in 1964, the catalyst particle aided vapor–liquid–solid (VLS) growth process, first reported by the production of NWs from diverse materials utilizing a range of physical sputtering, e‐beam, MBE, and CVD methods, has been intensively studied [53]. By using traditional methodologies for the development of the epitaxial structure through this VLS method, a precision alignment system may be obtained throughout NW formation. Inside the regulated fabrication of heavy nanofiller arrays and single‐wire devices, the approach VLS epitaxy proves to be advantageous [54]. If ZnO is grown multilayered on a flat crystal framework, it tends to enlarge in dimension and readily generates highly oriented arrangements (Figure 1.1a). For the GaN (Figure 1.1b) and Si/Ge structures, a comparable level of epitaxial regulation may be accomplished [55, 56]. This VLS approach may be used to create NW structures with strict shape control (<20 nm) [57, 58]. Advances in scanning and transmission electron microscopy (TEM) provided essential analytical tools for characterizing these materials in the following decades, paving the way for the fabrication of NWs in the field of advanced materials.
Figure 1.1 SEM image (a) on a plane sapphire wafer, ZnO nanowires, and (b) GaN nanowire arrays on plane LiAlO2 part.
Source: Pauzauskie and Yang [56], Elsevier.
1.2.2.3 Nanorods
Nanorods are an appealing component for research and often good alternatives for various applications due to their form anisotropy. Due to the increased stimulation of surface plasmons in nanoparticles produced by an increase in particle aspect ratio, nanorods have been shown to be more efficient than spherical particles. The strength of the dipole moment is notably significant within a nanoparticle due to the rise in surface plasmons [59]. As a result, the electrical field in nanorods increases in comparison with spherical particles. Significantly well‐oriented CdSe nanorods, according to Alivisatos and coworker, provided an effective, guided path for charge transporters to pass through the photoelectric device and be collected [60]. Inserting nanorods into P3HT films boosted extrinsic quantum yield by three times when the aspect ratio was raised from 1 to 10 nm [61]. While researching Ag nanorods for polystyrene composites by Winey et al., they discovered that the electrical conductivity of polymer composites is influenced by the aspect ratio of anisotropic nanoparticles. Particularly, because rod‐shaped particles have a lower percolation threshold than spherical particles [62], percolation threshold was discovered to be affected by both the form and size of nanoparticles. Many advantages in the underlying features of nanorods are projected to be shared by larger rod‐shaped particles, both in diameter and length. In conclusion, the aspect ratio, polydispersity, volume fraction, and alignment of nanorods have a significant impact on their efficacy [62].
In general, the development of nanorods in arrays requires a platform supplied by the substrate, which can be constructed of a variety of materials [63]. According to Oh et al., electrochemical gas sensors based on vertically oriented ZnO nanorod arrays (average length and diameter were 500 and 50 ppm, respectively) were successfully created (Figure 1.2a,b) [64, 65]. The devices can be made by introducing 39.5 W/cm ultrasound vibrations at 20 kHz into a solvent (such as 0.1 M zinc nitrate hexahydrate and 0.1 M hexamethylenetetramine) so that the organic material is submerged in the Al2O3 substratum, where the Pt conductor is stored, and Zn thin films are formed immediately [65].
Figure 1.2 SEM picture of ZnO nanorod (a) upper view and (b) oblique view.
Source: Yuan et al. [64], MDPI, CC BY 4.0.
1.3 Applications of 1D Hybrid Nanostructures
1.3.1 Gas Sensing
The need for the detection of the small extent of explosive, combustible, and poisonous gases and screening of environmental contamination has given way to the development of various gas sensors [66]. Medicine, agriculture, industrial refining, and environmental studies are the fields that have found the great application of these sensors. Among such highly flammable gases, sensing of lightest element hydrogen is one such case of implementation of gas sensors. It is undetectable by the human eye. Hydrogen on reaction with oxygen results in an inflammable compound that can be ignited with a flame or a spark. The fuel‐ for hydrogen‐powered vehicles and aeronautical operations are being provided by hydrogen [67]. Hydrogen screening is useful for a variety of reasons, from pollution detection to early warning indications of fires or nuclear reactor safety to presenting proof of certain diseases. Detecting the presence and quantity of hydrogen is useful in the manufacturing of semiconductors and the identification of imminent transformer failure in electric power plants. Other examples include volatile organic compounds (VOCs), which as the name suggests have a high vapor pressure [68]. VOCs are plentiful and omnipresent, with some posing a health risk to humans and others being damage to the environment. Hazardous VOCs are not usually dangerous, but if they are created within homes, they might cause sick building syndrome. VOCs can be found in human bodies, and on the other hand, some of the VOCs have intensified long‐term health consequences and some are even proven carcinogens [69]. A good sensor should have a high susceptivity, quick response, and good selectivity. The development of low‐cost and reliable gas sensors that can function at room temperature continues to be a significant scientific and technological obstacle. The detection methodology of the gas sensors can serve as a basis for the classification of various sensing materials and methods. Alterations in electric characteristics, visual, chromatographic, and calorimetric gas sensing are various methods of detection. When gas interacts with the surface of semiconductor gas sensor (metal chalcogenides, CNTs, and conducting polymer), it alters the main physical properties such as the electrical conductivity and work function of the sensing material [66]. Yang and coworkers used thermal oxidation in an oxygen atmosphere within a horizontal tube furnace to manufacture oriented ZnO nanobelt configurations natively on Zn substrates. The coverage of the ZnO nanobelt array on the substrate seems to be reasonably homogenous, with an aerial density of around 1014 nanobelts/m2[70]. These nanobelts have a root diameter of 100–300 nm, a length of 10–20 mm, and a thickness of 3–4 nm. ZnO nanobelt balls grow directly from Zn microparticles to generate a thick sheet, with the nanobelts precisely aligned on the microparticle surface, when a layer of micrometer‐sized Zn particles is used as the growth medium instead of Zn foil. The ammonia gas sensor made from such as‐grown ZnO nanobelt ball arrangements on Si substrates has a high sensitivity and quick responsiveness at room temperature [70, 71].
1.3.1.1 Safety Monitoring of Exhaust Gases in Automobile
Gas sensors are commonly found in modern automobiles and serve as either a commodity or a critical engine component [72]. Based on the concentrations of atmospheric gases detected in the air intake manifold, it is becoming increasingly common for a vehicle's electronic control unit (ECU) to naturally close and open the outside air flaps [73]. The most monitored gases are those which are combustible [74]. A pair of CO‐ and NO2‐sensitive sensors is commonly mounted to determine the air quality. Automobiles must now strictly adhere to rules to maintain adequate air quality index and, therefore, the gas sensors are now a part of their machinery [75]. The decrease in atmospheric contamination and increase in the fuel efficacy must be the aim of the automotive industries, and modern‐day gas sensors can help in achieving this goal by offering flexibility in the design and high sensitivity [72].
Electric car fires, chemically dangerous gas leaks and gas pipeline leaks, and explosions have occurred all around the world, and they are nearly typically caused by combustible and explosive gases such as hydrogen, carbon monoxide, hydrogen sulfide, and others [76]. Resistive gas sensors based on 1D nanomaterials have been thoroughly explored for monitoring common gases such as hydrogen, carbon monoxide, and hydrogen sulfide in order to avoid probable explosion and combustions [77]. These gas sensors offer excellent electronic transmission routes, high susceptibility, and chemical and thermal stability [78, 79]. Kumar et al. constructed Nb nanofibers (NFs) and a reversible and selective resistive gas sensor for room‐temperature CO gas detection. At room temperature, these sensors demonstrated CO responses of 22% for 2 ppm and 91% for 400 ppm and were more beneficial with fast response/recovery durations [80].
Wang and coworkers used two‐step procedures of VLS and atomic layer deposition (ALD) to create 1D SnO2/NiO core–shell nanowires (CSNWs) (Figure 1.3a). The SnO2/NiO‐100 sensor (with 100 ALD cycles) showed a substantial sensitivity of 114–500 ppm hydrogen below 500 °C, that is nearly fourfold more than virgin SnO2 NWs, and excellent selectivity even in a complex gas environment (ethanol, acetone, hydrogen, and NH3) (Figure 1.3b,c). SnO2/NiO CSNWs' increased hydrogen‐sensing performance was attributed to their high surface‐to‐volume ratio, the p–n heterojunction that evolved at the p‐NiO‐shell/n‐SnO2 core interface, and the effective modification of the NiO shell layer [81, 82]. Nikfarjam and coworkers used a unique electrospinning process with secondary electrostatic fields on electrodes with extremely sharp triangular and rectangular edges to create single‐aligned pure TiO2 NFs and gold nanoparticle (GNP)‐TiO2 NFs for gas‐sensing devices (Figure 1.3d,e). GNPs‐TiO2 NFs had a lower working temperature (250 °C) than pure TiO2 NFs and had high susceptibility (70–30 ppb CO) and a lower limit of detection (70 ppt) (Figure 1.3f,g). Through the local Surface Plasmon Resonance (LSPR) phenomenon, visible light can activate GNPs, decreasing the reaction’s activation energy in the process. It is observed that, when GNPs came into proximity of TiO2 nanograins, a Schottky barrier formed between them, and electrons passing from the TiO2 nanograins to the GNPs enlarged the TiO2 nanograins' depletion zone, reducing sensor conductivity. H2S is also one of the combustible and dangerous gases that, when subjected to heat or introduced to open flames, it can form an explosive mixture with air, resulting in combustion. More interestingly, it showed a ppb‐level H2S reaction in a gas combination containing H2S, acetone, and ethanol, with 85% humidity (Figure 1.3j). Pure SnO2 quantum wires and the GO nanosheet cooperated together to increase transducer performance and chemical reception, resulting in high responsiveness and specific gas sensing. Due to its room‐temperature fabrication, low‐temperature operation, and great compatibility with the paper substrate, the SnO2–GO sensor is a potential adaptable gas sensor. Song et al. used a simple mechanical stirring approach to make SnO2 quantum wire/GO nanosheets (Figure 1.3h). At low temperatures, the SnO2–GO sensor outperformed a pure SnO2 sensor in terms of responsiveness and specificity to H2S (Figure 1.3i) [83].
Figure 1.3 (a) Diagrammatic illustration of SnO2/NiO‐X CSNWs; (X is the number of atomic layer deposition cycles) (b) SEM image and sensing response of the SnO2/NiO‐X CSNWs heterostructures toward 200 ppm of H2 at 50 °C as a function of the NiO–shell layer thickness; (c) at 500 °C, the SnO2/NiO‐100 sensor response to 200 ppm H2 and additional interfering gases (300 ppm ethanol, 50 ppm acetone, and 20 ppm NH3); (d) TEM image of TiO2 NFs; (e) picture of the GNP–TiO2 sensor, time‐dependent response; (f) pristine TiO2 at 300 °C; (g) GNP–TiO2 at 250 °C in various concentration levels, (h) SEM image of SnO2–GO composites with schematic diagram; (i) at 700 °C, the detection performance of the SnO2 gas sensor and SnO2–GO gas sensor to various gases (10 ppm H2S, 10 ppm SO, 10 ppm NH3, 50 ppm acetone, and 50 ppm ethanol); and (j) the SnO2–GO gas sensor (70 °C, RH85%) was used to detect a lower content of H2S ranging from 200 to 1000 ppb in acetone (500 ppb) and ethanol (500 ppb) mixture.
Source: Wang et al. [81]/MDPI/Public Domain CC BY 4.0.
1.3.1.2 Health Monitoring
Gas sensors which are made up of semiconductors are used in practically every industry and have a wide range of applications. Underground miners are vulnerable to combustible gas, asphyxiates, lower oxygen levels, and other poisonous gases [84]. Anchored and transportable sensors are utilized to ensure that in the event of an emergency gas leak, audiovisual alerts are activated, allowing for a safe and quick evacuation of the manpower [85]. Similarly, many different gas detectors are used in the gas and oil industries because of the existence of dangerous random moving molecules, whether during production, transportation, processing, storage, or near distribution pipes [86]. Chemical facilities in almost every sector around the globe are responsible for the release of dangerous gases as by‐products during their processes which includes benzene, ethylene, propylene, and toluene produced by the petrochemical sector, H2S, and SO2 produced by the drilling and extraction industries, exposing people living near companies to harmful gases [87]. That makes the availability of highly efficient gas‐sensing systems in such sectors imperative.
In the food industry, smart food packaging involves a variety of gas sensors to determine the optimal food/meat aging time, monitor the quality of meat, and control food quality in general [87]. The clever packaging approach allows us to monitor the state of edibles as well as the package's surroundings [88]. As a result, using gas sensors in the food manufacturing and packing industries might dramatically minimize food waste while also lowering the annual number of food poisonings, therefore, enhancing food safety [89]. However, a few of the chemicals found in the body may be used for medical diagnostics, and detection of these unique gases has been proved to be useful in the diagnostic industry. Toluene (lung cancer), isoprene (heart disease), formaldehyde (lung cancer), and NH3 (hemodialysis) are few examples of such type of chemicals [89]. Ama et al. used nanocomposites including 1D KWO (K2W7O22) nanorods and 2D Ti3C2Tx nanosheets to construct a novel acetone sensor. These nanocomposites have a high acetone sensitivity (10 times that of a KWO‐based sensor), a considerable higher atmospheric condition tolerance, and months of increased stability, showing its promising application as a highly accurate as well as precise methanol detecting element in medical care and insulin treatment [90]. Wang et al. developed a poly(styrene‐butadiene‐styrene)/carbon nanotubes (SBS/CNT) hybrid fiber detector that used a modular wet spinning method to increase selectivity (19–10% solvent) across the entire sensing distance of 100–400 ppm, as well as a quick response (40 seconds) or brilliant mechanical dependability. This sensor showed a lot of potential for health monitoring in wearable and flexible electronic devices [91]. In an easy two‐stage CVD process, Gong et al. created a biosensor for alcohol depending on α‐Fe2O3/SnO2 heterogeneous structure. There was an increase in sensitivity with outstanding alcohol characteristics in systems based on solid SnO2 nanosheets or Fe2O3 nanorods. A heterojunction using 1D/2D hybridization designs (Fe2O3) could explain the higher productivity (SnO2). Furthermore, the Fe2O3/SnO2 had remarkable reproducibility, indicating these materials might be used in exhalation testing (Figure 1.4) [92].
Figure 1.4 The advancement of Fe2O3/SnO2 reaction.
Source: [92] Research A Science Partner Journal / Public Domain CC BY 4.0.
1.3.1.3 Environmental Monitoring
Poor air quality index in the urban areas are posing a threat to the health of the living beings in such areas. Many respiratory disorders and environmental issues can be tracked down to the emission of harmful gases from chemical power plants and petroleum and mining industries [93]. Natural, synthetic, and anthropogenetic gases are the three types of gaseous contaminants [94]. Natural causes of air pollution include volcano eruptions, wildfires, and lightning, whereas synthetic sources include emissions from human activities such as automobile exhaust gases, chemical disasters, or commercial activity, for example transformers and land disposal [95]. As a direct consequence of climate change due to the increase in the greenhouse gases, the need for monitoring such pollutants is more than ever [95]. The predominant objective of air pollution control is improvement in the air quality index and, therefore, reduced respiratory illness [96]. This includes a screening of gases like CO2, NO2, SO2, and O3 through befitting gas sensors [89]. Suh et al. developed an edge‐exposed WS2 manufactured on SiO2 NRs that can detect NO2 extremely accurately as well as precisely. It reacted to 5 ppm NO2 with a response that was significantly greater than the reaction to interfering gases at ambient temperature (3.44 ppm to CO and 0.47 ppm to H2S) [97]. The excellent performance of WS2 is largely due to its very porous 1D nanomaterials as well as highly sensitive interface regions, which serve as beneficial catalyst surfaces for immediate contact with specific atoms [98].
Lim et al. developed Au‐SnO2 NFs that can detect NO2 gas at low conditions while exposed to photons (Figure 1.5a). The sensor's exceptional transparency (93%) was aided by the incredibly minimal coverage of sensing materials (approximately 0.3%), allowing the substance to be completely open to the gas and, therefore, facilitate thermal detection as well as photosensibility process (Figure 1.5b). The packed Au particles amplified the reactivity to NO2 due to the surface plasmon resonance effect of Au. The sensor had increased responsiveness (300) in daylight to 5 ppm NO2, consistent response to sub‐ppm NO2, and a low activation range of 6 ppb with a high NO2 reaction in all dried or slightly moist atmospheres (50% and 70%, respectively) (Figure 1.5d,e). A gas sensor with high visibility and ambient temperature functionality would assist in improving transparent digital gadgets and optoelectronic devices which are directly connected to the Internet of Things (IoT) (Figure 1.5) [99]. To synthesize silver nanocrystal (NC)‐functionalized multiwalled carbon nanotubes (Ag NC‐MWCNTs), Cui et al. employed a simple mini‐arc plasma technique combined with an electromagnetic pressure assembling method (Figure 1.5f). When Ag NCs were added to MWCNTs, the susceptibility to NH3 gas was greatly enhanced (Figure 1.5g). The performance of the gas sensor is significantly influenced by the oxidized Ag surface. NH3 particles bind to Ag hollow areas on the AgO interface when H is directed against Ag. A positive energy exchange from NH3 to the Ag NC‐MWCNTs hybrid results in a conductance change. The sensor also had high selectivity for various gases and was easy to maintain over time (Figure 1.5h,i) [100].
Figure 1.5 (a) Au‐SnO2 NFs diagrammatic representation; (b) transparency detector images; (c) smart sensor component that can interact with smart phones; (d) resistivity shift in reaction to 5 ppm NO2 with white LED and sunshine; (e) for various environments; (f) Ag NC MWCNTs graphic demonstration; (g) room‐temperature multidimensional sensitivity reaction during Ag NCs decoration; (h) analysis of sensor responses to different chemicals; and (i) characterization of sensing reaction to 1% NH3 during four months of storage in air.
Source: Wang et al. [81], MDPI, CC BY 4.0.
1.3.2 Optoelectronic Application
Optoelectronics is among the most intriguing areas of applicability for hybrid nanostructures due to the ocular and electrical attributes of isolated semiconductors and metal nanoparticles [101]. Indeed, hybrid designs hold the possibility of combining greater potentiality, superior performance, and scaling down of optoelectronic devices, hence enhancing the performance of the device, speed, and power efficiency [101, 102]. The expanded features of hybrid nanostructures might have a significant impact on the disciplines of photodetection and PVs in particular. PV systems are often regarded as among the most efficient and essential strategies for meeting the rising world's energy demands [103]. From the many existing approaches, PVs are deemed being the safest technique to accomplish the desired results through solar energy conversion. Because of their capacity to cost‐effectively change conventional catalyst PV radiation as a supply of solar energy, small‐molecule and polymer‐based PVs have attracted much interest in both industry and academia [104]. Nanoscopic proportions and quicker carrier collection owing to short transit routes are some of the restrictions resolved by semiconductor NWs [55]. Decreasing dimensions underneath the typical absorption depth, on the other hand, impede effective light trapping, lowering overall efficacy. Metal nanostructures can be included in optoelectronics as well as PV‐nanostructured methods to improve optical absorbance by enhancing electrical charge [104]. For comparison, near‐field coupling between plasmonic nanostructures in close proximity to GaAs NWs was used to reroute electromagnetic waves into the semiconductor and increase intensity up to 20 times for the chosen wavelength and polarization, allowing for the customization of the nonlinear optical response of a single NW [55].
Hyun and coworkers used scanning visible light spectroscopy to correct a localized photocatalytic activity increase of 20% across a Si nanostructure coated with nanocomposite with the horizontal direction. The interaction with the electromagnetic spectra was improved by narrowing the gap between the metallic nanoparticles as well as the Si nanostructure to the semi‐region, leading to a twofold increase in photocurrent over the unprotected NWs [105]. Grinblat et al. created ZnO nanostructure by inserting a gold qualitative oligomer within the electric current hotspots. The author has also reported the interplay between leaky‐mode resonances (LMRs) in NWs and limited interface vibrational modes. LMRs are electronic patterns provided by a dielectric cavity in a single silicon‐based nanostructure, wherein absorbance is resonance increased. The leaky nature of all these phases aided the interfacial resonances of metallic nanoparticles on the NW substrate. The ensuing coupling allows for the suppression, enhancement, and shifting of absorption resonances, greatly increasing the amount of control over tenability and optical characteristics modulation [106]. Knight et al. investigated the alternative mechanism of hot electron emission through plasmonic degeneration for sensor applications for the first time [107]. Using temperatures beyond the optoelectronic visible region, this indicated system, which was composed of such an arrangement of Au nanostructures constructed atop an n‐type Si surface, produced a vibrational frequency and isotropic photon energy with a maximum value of 0.01%. This concept was recently accomplished in near‐infrared photodetection devices made of Au nanorods and ZnO NWs. Au nanorod surface plasmons were utilized as reactive ingredients in the suggested idea to create or transmit hot electrons into the huge absorption coefficient ZnO NW, functioning as an inactive material for electronic conductivity. Kawawaki and coworkers enhanced the near‐infrared absorbance of PbS QD/ZnO NW PV by integrating Ag nanotubes, improving the electrical properties from 4.5% to 6%. Inside the solid‐state p–n power generation system, core–shell silicon NW PVs ornamented with single silver nanomaterials indicated short‐wave progression of the short‐circuit current (i.e. absorption) emerging both from near‐field and far‐field coupling with dipolar and quadrupolar nanocrystalline spectra [108]. Weiwei et al. established a solution‐phase technique to create a CsPbX3/ZnS QDs heterodimer with improved chemical stability and systematic density functional theory‐based first‐principles calculations backed up this claim. When combined with ZnS, CsPbX3 exhibits excellent charge dispersion, which is advantageous for PV employments [109].
1.3.2.1 Photodetector
Quantum confinement effects can extend bandgaps in nanostructures, and direct bandgaps in semiconductors vary from 1.5 eV (CdTe) to 3.7 eV (ZnS). As a result, nanostructures have a lot of promise for applications such as near infrared (NIR) to UV nanophotodetectors (nano‐switches) [55]. Nanostructures are estimated to have substantially greater efficiency and economics than standard film and bulk devices due to their higher absorption coefficient and chemical stability. Several proof‐of‐concept composite NW photocatalysts were produced due to the increased optical emission in modified nanomaterials [110, 111]. Luo et al. showed a considerable improvement in photodetection effectiveness of CdSe nanoribbons decorated with Au hollow nanoparticles when compared to bare CdSe nanoribbons and nanoribbons adorned with solid nanoparticles [112]. In addition, Au‐decorated CdSe and CdTe NWs, Au‐decorated ZnO/ZnCdSeTe CSNWs, Ag‐decorated ZnO nanorod array LEDs, and Si NW arrays covered with Au nanomaterial‐coated graphene sheets all demonstrated superior plasmon increased light transfer efficiency [112].
Dong and Huang et al. utilized a large bandgap hole transport layer with perovskite photoactive layers to create a highly efficient PV‐type photodetector [113]. A photodetector with a ZnSe nanoribbon/Si p–n heterojunction was built by Wang and coworkers to augment the functioning of the ZnSe nanoribbon/Si p–n heterojunction system for which Ag nanoparticles were added (Figure 1.6a–c). The system with Ag nanoparticles had a receptivity and detectivity of 184.8 mA/W and 9.201 cm Hz1/2 W−1, respectively, compared to 117.2 mA/W and 5.86 cm Hz1/2 W−1 for the system without silver nanomaterial [114]. The very kinetic hot electrons from regionalized surface plasmon resonance stimulation of metallic plasmonic nanoparticles may swiftly migrate to the surrounding ZnSe nanoribbon with a comparable high energy once the heterojunction is illuminated by light [114]. High‐performance photodetectors based on hybrid perovskite PV cells have been disclosed by Dou et al. Under standard circumstances, these PV panels seem to have an electrical performance of around 12% [115].
Figure 1.6 (a) Schematic depiction of localized surface plasmon resonance induced e‐transfer from nanomaterials in ZnSe nanoribbon, (b) schematic diagram of the energy bandgap of ZnSe nanoribbon Si heterostructure enhanced with Ag nanomaterial with visible light, and (c) at low voltages, time‐domain spectra of the circuit with and without decorating nanomaterials.
Source: Zhang [102] / MDPI / Public Domain CC BY 4.0.
1.3.2.2 Solar Cell
The bulk semiconductors in the II–VI group have large binding energy and greater light‐emitting and transmission coefficients [116]. By integrating semi‐material with distinct bandwidth, each section of the heterojunction may preferentially absorb sunlight in a specific spectral region, resulting in more light absorption and better light usage [117]. As a result, heterojunctions have shown great potential in the improvement and advancements of solar cells. CdTe is a viable candidate for solar applications, with a bandgap of 1.45 eV and a greater absorption coefficient [118]. Because a 2 mm CdTe layer absorbs nearly all input direct sunlight, the p‐CdTe/n‐CdS heterostructures are the least common PV arrangement. Solar cells must be stable to be used in meaningful implementations. Nonetheless, perovskite‐based materials, such as CsPbI3, which are widely used in PVs, are unsteady and rapidly transition to solar cell that optimized light absorption by rising the interfacial region as well as illumination entrapment. These results mentioned possibilities for solar absorber material selection. TiO2–SiO2 is the cubic perovskite phase in the atmosphere [118]. Wu et al. created solar systems made of CdS, including Ga nanoribbons and Si heterojunctons. During UV activation, the transistors showed PV activity, exhibiting open‐circuit photovoltage and short‐circuit current of 0.45 V and 3.49 nA, respectively, resulting in a throughput of 44.1% and an energy transfer effectiveness of 1.2% [119].
Zhang and coworkers presented a type II ZnO/ZnSe core–shell nanostructure antireflection materials, which may increase the refractive indices duration via a scattered phenomenon or by producing an optical properties variation in Cu(In, Ga)Se2 PV [120]. Since using the TiO2–SiO2 core–shell nanostructures to reduce reflectance the efficiency of power conversion increased from 6.32% to 7.00%. CdS/Cu2S CSNW solar cells were fabricated by Zhang et al. which had greater open‐circuit voltage and fill factor than comparable planar cells and also a 5.4% energy conversion efficiency which is equivalent to their counterpart planar cells when light absorption levels are low. They also used many cells on single nanostructures including both equivalent and consecutive topology to get high emission voltages and currents (Figure 1.7a–f) [102]. A reduced solution‐based covalent bond approach, which might also establish a nanocrystalline interface within a single‐crystalline CdS core and single‐crystalline Cu2S shell, is thought to be responsible for the remarkable photocatalytic efficiency of CdS/Cu2S core–shell nanostructures [121].
Figure 1.7 (a) SEM picture of a PV unit with yellow and brown artificial dyes highlighting CdS and Cu2S, accordingly; (b) I–V property of a fundamental nanowire exposed with (AM1.5G); (c) SEM picture of triple PV units in a sequence of a separate nanowire, showing the brown shapes indicating the core–shell areas; (d) the I–V properties of the parallel devices within one sunlight irradiation (AM1.5G) demonstrate that the voltages add and the current remains unchanged; (e) SEM view shows four PV units off the single nanowire simultaneously, with brown boxes indicating the core–shell areas; and (f) during irradiation (AM1.5G), the I–V property of the four perpendicular devices shows that the currents accumulate and the voltage remains constant.
Source: Zhang et al. [102], MDPI, CC BY 4.0.
1.3.2.3 Light‐Emitting Diode
In a perfect PV material, the Shockley–Queisser limit asserts that radioactive decay is the only mechanism for charge recombination [122]. Owing to the recent significant growth in PV efficiency, it has been discovered that hybrid perovskites have extremely high PL quantum yields, which are near 70% at room temperature and nearing 100% at 195 K. This justifies the remarkable PV performance and also actively supports light‐emitting device applicability [123]. Huang et al. have made significant change in building electronically driven electroluminescent diode, for example micro‐LED, using a variety of semiconductor nanostructures [124]. Despite utilizing nanostructured transistors' growth to create p–n junctions, they employed a linked p‐ and n‐type NW technique. Additional NW processes have now been connected to the InP NWs electrode, such as p‐Si/n‐GaN, p‐GaN/n‐GaN, p‐Si/n‐CdS, and p‐Si/n‐CdSe [124, 125]. Ye et al. produced short‐chain organic linker attached CsPbBr3 NCs at room temperature in an ambient atmosphere [126]. They eventually succeeded in fabricating CsPbBr3 NCs‐based LED with a brightness of 5033 Cd/m−2, an external quantum efficiency (EQE
