Controllable Fabrication of Zinc Oxide Functional Nano-/micro-structure in Aqueous Solution PDF Download
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Author: Xiaodong Yan
Publisher:
ISBN:
Category : Nanostructured materials
Languages : en
Pages : 312
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Book Description
Nanostructures of ZnO show intriguing chemical, electrical, and physical properties and are promising for a broad range of applications in catalysis, electronics and photonics. Cost-effective techniques that can be used to prepare structures with controllable compositional, structural, and functional properties are fundamental to the utilization of ZnO in small scale devices with enhanced performance. Although many methods have been developed to fabricate ZnO nanostructures, systematic research on functional materials development based on ZnO is still needed as this fascinating material probably has the richest family of low-dimensional nanostructures. The research reported in this thesis aims to develop ZnO-based nanostructural materials using a facile and low-temperature aqueous solution growth approach, to analyze their compositional, mechanical, structural, and functional properties using advanced characterization techniques, to get a better understanding of the mechanisms behind nanostructure growth, and to explore their potentials in catalytic, optical, and electronic applications. In the first part of this thesis, low-dimensional ZnO nano-/micro-rods with tailored structural property (growth direction, aspect ratio, and surface distribution density) were grown on glass substrates in aqueous solutions containing zinc salt and hexamethylenetetramine at temperatures generally lower than 95oC. The substrates were pre-deposited with a thin layer of ZnO seeds using a magnetron sputter. The potential influences of growth conditions, typically including concentration, pH, type of zinc salt, solution temperature, reaction duration, and inorganic or organic additive, have been subjected to systematic investigation. This led to an improved understanding of the chemical reactions and nucleation/growth processes involved in the morphological evolution of ZnO-based hierarchical nanostructures. The second part of the thesis, ZnO nano-/micro-rod arrays with controllable distribution density have been successfully synthesized by adjusting the initial pH of the weak acidic growth solution. ZnO arrays with a large inter-rod space provide a good opportunity for characterizing the property of an individual rod. In this research, mechanical property tests have been successfully peformed directly on a single rod without the need of any complicated sample preparation. The electronic properties of these aligned ZnO nanorod arrays have also been explored by studying the I-V characteristics of both heterojuction and homojuction p-n devices. In next two chapters, complex ZnO structures, including nanotubes and three-dimensional ball-shaped clusters have been presented and disscussed, respectively. The morphology and microstructure of these structures were characterized by scanning electron microscopy, transmission electron microscopy, and in-situ cathodoluminescence. The corresponding growth mechanisms were proposed based on the analysis of the characterization results. Chapter 7 describes that aligned ZnO nano-rod arrays were further used as templates to prepare a novel composite nanostructure. By coating these ZnO nanorods with TiO2 nanowires using magnetron sputtering technique, a ZnO/TiO2 core-brush structure has been successfully achieved. Their morphology and microstructure have been investigated using scanning electron microscopy, transmission electron microscopy, powder X-ray diffractometer, energy-dispersive X-ray spectroscopy and X-ray Photoelectron Spectroscopy. This composite nanostructure shows a significantly enhanced photocatalytic activity in decomposition of a typical organic dye under UV and sunlight irradiation. This new structure has many other interesting properties and may have great potential in other optoelectronic applications. In the last part of this thesis, conclutions and future works are addressed according to the synthesis, characterization and application results.
Author: Xiaodong Yan
Publisher:
ISBN:
Category : Nanostructured materials
Languages : en
Pages : 312
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Book Description
Nanostructures of ZnO show intriguing chemical, electrical, and physical properties and are promising for a broad range of applications in catalysis, electronics and photonics. Cost-effective techniques that can be used to prepare structures with controllable compositional, structural, and functional properties are fundamental to the utilization of ZnO in small scale devices with enhanced performance. Although many methods have been developed to fabricate ZnO nanostructures, systematic research on functional materials development based on ZnO is still needed as this fascinating material probably has the richest family of low-dimensional nanostructures. The research reported in this thesis aims to develop ZnO-based nanostructural materials using a facile and low-temperature aqueous solution growth approach, to analyze their compositional, mechanical, structural, and functional properties using advanced characterization techniques, to get a better understanding of the mechanisms behind nanostructure growth, and to explore their potentials in catalytic, optical, and electronic applications. In the first part of this thesis, low-dimensional ZnO nano-/micro-rods with tailored structural property (growth direction, aspect ratio, and surface distribution density) were grown on glass substrates in aqueous solutions containing zinc salt and hexamethylenetetramine at temperatures generally lower than 95oC. The substrates were pre-deposited with a thin layer of ZnO seeds using a magnetron sputter. The potential influences of growth conditions, typically including concentration, pH, type of zinc salt, solution temperature, reaction duration, and inorganic or organic additive, have been subjected to systematic investigation. This led to an improved understanding of the chemical reactions and nucleation/growth processes involved in the morphological evolution of ZnO-based hierarchical nanostructures. The second part of the thesis, ZnO nano-/micro-rod arrays with controllable distribution density have been successfully synthesized by adjusting the initial pH of the weak acidic growth solution. ZnO arrays with a large inter-rod space provide a good opportunity for characterizing the property of an individual rod. In this research, mechanical property tests have been successfully peformed directly on a single rod without the need of any complicated sample preparation. The electronic properties of these aligned ZnO nanorod arrays have also been explored by studying the I-V characteristics of both heterojuction and homojuction p-n devices. In next two chapters, complex ZnO structures, including nanotubes and three-dimensional ball-shaped clusters have been presented and disscussed, respectively. The morphology and microstructure of these structures were characterized by scanning electron microscopy, transmission electron microscopy, and in-situ cathodoluminescence. The corresponding growth mechanisms were proposed based on the analysis of the characterization results. Chapter 7 describes that aligned ZnO nano-rod arrays were further used as templates to prepare a novel composite nanostructure. By coating these ZnO nanorods with TiO2 nanowires using magnetron sputtering technique, a ZnO/TiO2 core-brush structure has been successfully achieved. Their morphology and microstructure have been investigated using scanning electron microscopy, transmission electron microscopy, powder X-ray diffractometer, energy-dispersive X-ray spectroscopy and X-ray Photoelectron Spectroscopy. This composite nanostructure shows a significantly enhanced photocatalytic activity in decomposition of a typical organic dye under UV and sunlight irradiation. This new structure has many other interesting properties and may have great potential in other optoelectronic applications. In the last part of this thesis, conclutions and future works are addressed according to the synthesis, characterization and application results.
Author: Teofil Jesionowski
Publisher: MDPI
ISBN: 3039213970
Category : Science
Languages : en
Pages : 204
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Book Description
The book deals with novel aspects and perspectives in metal oxide and hybrid material fabrication. The contributions are mainly focused on the search for a new group of advanced materials with designed physicochemical properties, especially an expanded porous structure and defined surface activity. The proposed technological procedures result in an enhanced activity of the synthesized hybrid materials, which is of great importance when considering their potential fields of application. The use of such materials in different technological disciplines, including aspects associated with environmental protection, allows for the verification of the proposed synthesis method. Thus, it can be stated that those aspects are of interdisciplinary character and may be located at the interface of three scientific disciplines—chemistry, materials science, and engineering—as well as environmental protection. Furthermore, the presented scientific scope is in some way an answer to the continuous demand for such types of materials and opens new perspectives for their practical use
Author: Kamlendra Awasthi
Publisher: Elsevier
ISBN: 0128189010
Category : Technology & Engineering
Languages : en
Pages : 781
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Book Description
Nanostructured Zinc Oxide covers the various routes for the synthesis of different types of nanostructured zinc oxide including; 1D (nanorods, nanowires etc.), 2D and 3D (nanosheets, nanoparticles, nanospheres etc.). This comprehensive overview provides readers with a clear understanding of the various parameters controlling morphologies. The book also reviews key properties of ZnO including optical, electronic, thermal, piezoelectric and surface properties and techniques in order to tailor key properties. There is a large emphasis in the book on ZnO nanostructures and their role in optoelectronics. ZnO is very interesting and widely investigated material for a number of applications. This book presents up-to-date information about the ZnO nanostructures-based applications such as gas sensing, pH sensing, photocatalysis, antibacterial activity, drug delivery, and electrodes for optoelectronics. Reviews methods to synthesize, tailor, and characterize 1D, 2D, and 3D zinc oxide nanostructured materials Discusses key properties of zinc oxide nanostructured materials including optical, electronic, thermal, piezoelectric, and surface properties Addresses most relevant zinc oxide applications in optoelectronics such as light-emitting diodes, solar cells, and sensors
Author: , Prof. Dr. Ahmed Nahhas
Publisher: BoD – Books on Demand
ISBN: 1789239575
Category : Technology & Engineering
Languages : en
Pages : 148
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Book Description
This book presents a review of recent advances in ZnO-based nanomaterials and devices. ZnO as a nanomaterial has gained substantial interest in the research area of wide bandgap semiconductors and is considered to be one of the major candidates for electronic and photonic applications. ZnO has distinguished and interesting electrical and optical properties and is considered to be a potential material in optoelectronic applications such as solar cells, surface acoustic wave devices, and UV emitters. ZnO's unique properties have attracted several researchers to study its electrical and optical properties. As a nanostructured material, ZnO exhibits many advantages for nanodevices. Moreover, it has the ability to absorb the UV radiation.
Author: Yoshitake Masuda
Publisher: BoD – Books on Demand
ISBN: 9533079126
Category : Science
Languages : en
Pages : 368
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Book Description
We face many challenges in the 21st century, such as sustainably meeting the world's growing demand for energy and consumer goods. I believe that new developments in science and technology will help solve many of these problems. Nanofabrication is one of the keys to the development of novel materials, devices and systems. Precise control of nanomaterials, nanostructures, nanodevices and their performances is essential for future innovations in technology. The book "Nanofabrication" provides the latest research developments in nanofabrication of organic and inorganic materials, biomaterials and hybrid materials. I hope that "Nanofabrication" will contribute to creating a brighter future for the next generation.
Author: 蔡雨霖
Publisher:
ISBN:
Category :
Languages : en
Pages : 186
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Book Description
Author:
Publisher:
ISBN:
Category :
Languages : en
Pages : 1024
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Book Description
Author: Samira Bagheri
Publisher: CRC Press
ISBN: 1351818341
Category : Science
Languages : en
Pages : 157
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Book Description
Nanotechnology has become one of the most important fields in science. Nanoparticles exhibit unique chemical, physical and electronic properties that are different from those of bulk materials, due to their small size and better architecture. Nanoparticles can be used to construct novel sensing devices; in particular electrochemical sensors. Electrochemical detection is highly attractive for the monitoring of glucose, cancer cells, cholesterol and infectious diseases. Unique nanocomposite-based films proposed in this book open new doors to the design and fabrication of high-performance electrochemical sensors.
Author:
Publisher: Newnes
ISBN: 0080932282
Category : Science
Languages : en
Pages : 3572
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Book Description
Semiconductors are at the heart of modern living. Almost everything we do, be it work, travel, communication, or entertainment, all depend on some feature of semiconductor technology. Comprehensive Semiconductor Science and Technology, Six Volume Set captures the breadth of this important field, and presents it in a single source to the large audience who study, make, and exploit semiconductors. Previous attempts at this achievement have been abbreviated, and have omitted important topics. Written and Edited by a truly international team of experts, this work delivers an objective yet cohesive global review of the semiconductor world. The work is divided into three sections. The first section is concerned with the fundamental physics of semiconductors, showing how the electronic features and the lattice dynamics change drastically when systems vary from bulk to a low-dimensional structure and further to a nanometer size. Throughout this section there is an emphasis on the full understanding of the underlying physics. The second section deals largely with the transformation of the conceptual framework of solid state physics into devices and systems which require the growth of extremely high purity, nearly defect-free bulk and epitaxial materials. The last section is devoted to exploitation of the knowledge described in the previous sections to highlight the spectrum of devices we see all around us. Provides a comprehensive global picture of the semiconductor world Each of the work's three sections presents a complete description of one aspect of the whole Written and Edited by a truly international team of experts
Author: Santhosh Sankaranarayanan Nair
Publisher:
ISBN:
Category :
Languages : en
Pages : 272
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Book Description
AbstractNano/micro scale devices have attracted a lot of interest due to the emergence of wearable/portable devices. One of the challenging tasks in the miniaturization is to reduce the size and weight of the powering unit. Harvesting mechanical energy and making the device a self-powered one, not only helps in reducing the size/weight ratio but also in designing a maintenance free and sustainable device. Piezoelectric energy harvesting research has gained new momentum with the discovery of piezoelectric charges in semiconducting zinc oxide nanowires (ZnO NWs). Semiconducting ZnO NWs provide an opportunity to integrate with electronic devices and circuits directly unlike non-conducting traditional piezoelectric materials. The coupling of piezoelectric and semiconducting properties was used to design energy generating devices called nanogenerators (NGs). The basic working principle involves application of a mechanical force to create a piezopotential across the wurtzite structured NWs and this piezopotential is channelled employing metal-semiconducting pathways such as p-n junctions. These junctions also play a key role in various other devices such as solar cells, capacitors, fuel cells and water splitting devices. This thesis concentrates mainly on the fabrication of semiconducting piezoelectric nanowires on functionalised flexible substrates and the junctions thereby obtained. It is based on the idea that ZnO NWs can be grown directly on poly(3,4-ethylendioxydithiophene) (PEDOT) or graphene-functionalised substrates using low temperature aqueous synthesis. ZnO NWs can be fabricated using a low temperature aqueous processing route on flexible substrates and fibres. ZnO creates a wide variety of nanostructures due to the polar terminating layers and the surface chemistry of the substrate. The position of the substrate in the growth solution was therefore investigated and found to dictate the morphology and aspect ratio of the nanostructure in seed mediated low temperature aqueous synthesis on polyethersulfone (PES)-based flexible substrates. Vapour phase polymerisation was used to fabricate PEDOT coated 2-D and 3-D PES. To produce graphene-coated flexible substrates, colloidal graphene was synthesized and functionalised onto 2-D and 3-D PES using layer by layer technique (LbL) with polyelectrolytes such as polyallylamine hydrochloride (PAH) and polystyrenesulfonate (PSS). The LbL modification was achieved by exploiting the surface functional groups in the colloidal graphene. Various surface treatments and heat treatments were carried out to tune the system to obtain higher conductivity. ZnO seed solution was coated and NWs were grown on the functionalized substrates. The newly formed junctions were characterised for their I-V characteristics to determine if they have similar function to junctions formed with ZnO on ITO or metals. ZnO NWs grown on PEDOT shows an ohmic contact and gives linear I-V characteristics. On the other hand when a PEDOT coated substrate was made to form a junction at the top of the ZnO NWs, it forms a Schottky contact and gives rectification. However the ZnO-graphene interface shows a Schottky contact. When a top graphene electrode was made to form a junction with ZnO NWs grown on graphene, the I-V characteristics shows a symmetrical and rectifying junction on both sides. Nanogenerators were designed and tested using ZnO NWs grown on PEDOT coated 2-D and 3-D PES. Thus, the fabricated PEDOT-NGs produced a higher current by a factor of 106 and a 102 times increase in the voltage compared to the traditional ITO grown NG design. Vapour phase polymerised PEDOT on flexible substrates eliminated the use of expensive and less efficient electrodes such as ITO and Au. It has also been shown that this approach can be extended to fibre substrates by sandwiching them between PEDOT sheets which make them more suitable for wearable energy harvesting with 102 times improved efficiency compared to ITO sandwiched fibre NG. The higher performance of PEDOT NGs was accounted by the new junctions formed at the interfaces which reduce the screening of free charge carriers in the system. Graphene NGs were fabricated using gold top electrodes. The NG fabricated on surface treated PES was found to outperform the NG fabricated without surface treatment due to the higher conductivity of the surface treated electrode. The output of the surface treated NG was found to be much less than the ITO based or PEDOT based NGs.
