The introductory chapter discusses the scope, state of the art, preparation methods, new challenges and opportunities concerning metal oxide nanocomposites. Chapter 2 gives a more detailed review of structure-property relationships. Included in the many topics discussed in this chapter are the functions of fibers and matrix, classification of composites, matrix-based composites, reinforcements, polymer composites, composites processing, product fabrication, application, and special features of composites, along with their advantages and disadvantages compared with metals.
Graphene-based metal and metal oxide nanocomposites are introduced in Chapter 3. In this chapter, the authors discuss graphene, reduced graphene oxide, graphene-based composites and hybrid nanocomposites, mechanics of graphene nanocomposites, covalent and noncovalent functionalization and thermal properties. Chapter 4 on carbon nanotube–metal oxide nanocomposites introduces carbon nanotubes, including packaging applications, followed by different topics such as synthesis methods, environmental applications, environmental fate, transport, transformation, and environmental implications; and concludes with the direction that future research might take.
Two main topics are addressed in Chapter 5. The first is nanocomposite photocatalysts based on metal oxide, including those based on TiO2, ZnO and WOx. The second topic, the application of metal oxide composites in photocatalysis, includes a discussion of water splitting for hydrogen generation, photodegradation of pollutants and wettability patterning based on photocatalysts. Chapter 6 is a structural analysis of metal oxide nanocomposites for sensor applications. Following an introduction to the subject matter, the chapter goes on to discuss binding of metal oxide with imidazole and silane, characterizations, absorption and emission characteristics, and sensing mechanisms.
Thermal property analysis of metal oxide nanocomposites is discussed in Chapter 7. In this chapter the authors explain the use of metal and metal oxide nanoparticles in thermal management and synthesis procedures, the mechanism of thermal conductivity enhancement and thermal conductivity modeling of nanofluids. In Chapter 8 there is a two-part discussion on the topic of semiconducting metal oxides for photocatalytic and gassensing applications. The first part covers topics such as organic dyes as a major source of water pollution, conventional methods used for dye degradation, advanced oxidation processes, the role electronic structure of semiconducting metal oxide plays in photocatalysis, basic principles of photocatalysis, oxidizing species generation mechanism, semiconductor photocatalysts, kinetic studies of semiconductor photocatalysis and parameters affecting dye degradation. The second part of the chapter covers topics such as the evolution of gas sensors and their necessity, metal oxides as gas sensors, the gas-sensing mechanism of metal oxides and factors influencing sensor performance.
Metal oxide-based nanocomposites and their many applications are the subject of Chapter 9. It covers their use in the food and agricultural sector and in medicine due to their water barrier, thermal and flame-retardant properties, and their ability to disinfect water and improve water flux. Also discussed are nanocomposite membrane assemblies for water treatment prepared by non-solvent induced phase separation method, their adsorption performances, and their suitability for electrocatalytic, biosensor and sensing applications. Next, in Chapter 10, energy harvesting and sensing applications of triboelectric nanogenerators (TENG) are presented. Among the topics discussed are the working mechanism of a triboelectric nanogenerator, how to select materials for your TENG, basic operating modes of TENG, TENG as mechanical energy harvester, and TENG based on vertical contact separation mode, lateral sliding mode, single electrode mode and free-standing triboelectric layer mode. The final chapter on metal oxide nanocomposites for water purification includes several topics such as adsorptive removal of water pollutants; and the use of metal oxide nanocomposites for photocatalytic decomposition of water pollutants, removal and decomposition of inorganic pollutants, and decomposition of organic pollutants.
In conclusion, we would like to express our sincere gratitude to all the contributors to this book, whose commitment and sincerity shown towards their contributions, along with their enthusiasm and excellent support, enabled the successful completion of this venture. We would also like to thank all the reviewers who have taken their valuable time to make critical comments on each chapter. Finally, our thanks go out to Scrivener Publishing for recognizing the demand for such a book and realizing the increasing importance of the area of metal oxide nanocomposites and their synthesis and applications.
Dr. B. Raneesh Dr. Visakh P. M. November 2020
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Metal Oxide Nanocomposites: State-of-the-Art and New Challenges
Visakh P.M.1* and B. Raneesh2
1Department of Physical Electronics, TUSUR University, Tomsk, Russia
2Department of Physics, Catholicate College, Pathanamthitta, Kerala, India
Abstract
This first chapter discusses about the metal oxide nanocomposites: synthesis and applications with many different topics such as introduction to nanocomposites, graphene-based metal, metal oxide nanocomposites, carbon nanotube–metal oxide nanocomposites, metal oxide-based nanocomposites application towards photocatalysis, metal oxide nanomaterials for sensor applications, metal oxide nanocomposites and its thermal property analysis, semiconducting metal oxides for photocatalytic and gas sensing applications, and other potential applications of metal oxide-based nanocomposites.
Keywords: Metal oxide nanocomposites, carbon nanotube, graphene, photocatalysis, gas sensor
1.1 Introduction to Nanocomposites
The composite materials composed of polymer matrix are easily processible and readily available and therefore widely used in various industries. In composite materials, the fiber acts as load carrier with its strength being greatest along the axis of the fiber. The long continuous fibers aligned in the direction of the load leads to the formation of composite with much enhanced properties than the pure matrix material. Research studies reveal that the spider’s web fibers are much stronger than man-made processed fibers. In ancient civilizations across the world, husks or straws mixed with clay have been widely utilized to build houses that last longer for several hundred years [1]. The matrix material in composites serves two important purposes: (a) binding the reinforcement phases in place and (b) uniformly distributing the stresses among the constituent reinforcement materials in the event of an applied force. The matrix offer weight advantages and ease of handling. The inorganic materials, polymers and metals can be utilized as matrix materials in the designing of structural composites [2]. Thermoplastics resins are generally used as molding