The Multiple Roles of Diatoms in Environmental Applications: Prospects for Sol-Gel Modified Diatoms

Abstract

5.6 PH Sensors. This volume provides expert coverage of the state-of-the-art in sol-gel materials for functional applications in energy, environment and electronics. The use of sol-gel technology has become a hotbed for cutting edge developments in many fields due to the accessibility of advanced materials through low energy processes. The book offers a broad view of this growing research area from basic science through high-level applications with the potential for commercialization and industrial use. Taking an integrated approach, expert chapters present a wide range of topics, from photocatalysts, solar cells and optics, to thin films and materials for energy storage and conversion, demonstrating the combined use of chemistry, physics, materials science and engineering in the search for solutions to some of the most challenging problems of our time. Offers a complete reference for sol-gel materials for functional applications Provides detailed coverage of a growing field Presents a wide range of applications, from photovoltaics and battery materials through coatings, materials for waste water treatment, microelectronics and ferroelectrics Represents essential reading for advanced undergraduate and graduate students, Ph. D. researchers, postdocs and academic and industry researchers working in the areas of materials science, engineering, chemistry and nanotechnology. The International Sol-Gel Society (ISGS); Preface; Contents; Contributors; 1 An Introduction to Sol-Gel Processing for Aerogels; 1.1 Introduction; 1.2 Silicon Alkoxide Sol-Gel Materials; 1.3 Sodium Silicate Sol-Gel Materials; 1.4 Wet Gel Formation; 1.5 Acid-Catalysed Wet Gel Formation; 1.6 Base-Catalysed Wet Gel Formation; 1.7 Acid-Base Catalysed Wet Gel Formation; 1.8 Ageing of Gels; 1.9 Drying of Gels; 1.10 Surface Modification and Solvent Exchange; 1.11 Conclusions; References; 2 Sol-Gel Materials for Varistor Devices; 2.1 Varistors-An Introduction. 2.2 Conventional Preparation of Varistors2.3 Chemical Synthesis Strategies for Varistor Particles; 2.4 Advantages of Sol-Gel Technology for Varistors; 2.5 Sol-Gel Varistors; 2.6 High-Performance Varistors: Through Nanoinclusions; 2.6.1 Grain Size Reduction and Grain Boundary Area Improvement; 2.6.1.1 Addition of Nanofillers; 2.6.1.2 Adopting Controlled Sintering Methods; 2.6.2 Homogeneous Dopants Distribution at the Grain Boundaries; 2.6.2.1 Conducting Wet Chemical Syntheses; 2.6.2.2 Performing Temperature Controlled Step-Sintering Processes. 2.6.3 Use of Economic and High-Quality Raw Materials2.7 Sol-Gel Ceramic-Polymer Composite Varistors; 2.7.1 Varistor-Epoxy Composites; 2.7.2 ZnO-PANI Composites; 2.7.3 ZnO-PANI-PVA Composites; 2.7.4 GaAs-PANI-PE Composites; 2.7.5 Si-Polymer Composite Varistors; 2.8 Conclusions; References; 3 Sol-Gel Derived Functional Coatings for Optics; 3.1 Introduction; 3.1.1 Sol-Gel Chemistry and Optical Coatings: An Industry-Driven Development; 3.1.2 Sol-Gel Strategies Toward Original Optical Properties; 3.1.3 Liquid Deposition Techniques; 3.2 Sol-Gel-Based Multifunctional Antireflective Coatings. 3.2.1 Fundamentals of Antireflective Coatings3.2.2 Gradient-Type Antireflective Coatings; 3.2.3 Interference-Type Antireflective Coatings; 3.2.4 Weather-Resistant and Self-cleaning Antireflective Coatings; 3.3 Sol-Gel-Based Photonic Crystals; 3.3.1 1D Photonic Crystals; 3.3.2 2D Photonic Crystals; 3.3.3 3D Photonic Crystals; 3.4 General Conclusions and Perspectives; References; 4 The Multiple Roles of Diatoms in Environmental Applications: Prospects for Sol-Gel Modified Diatoms; 4.1 Overview; 4.2 Introduction to Diatoms; 4.3 Modification of Diatom Frustule Chemistry. 4.3.1 Coating Strategies to Modify the Diatom4.3.2 Chemical Conversion and Replication Strategies to Modify the Diatom; 4.3.3 Sol-Gel Inspired Approaches to Modify the Diatom Frustule Using Organoalkoxysilanes; 4.4 The Role of Diatoms as Bioindicators and Bioremediation Agents; 4.5 Limitations and Perspective; Acknowledgments of Funding; References; 5 Sol-Gel Sensors; 5.1 Introduction; 5.2 Gas Sensors; 5.2.1 Oxygen; 5.2.2 Carbon Dioxide; 5.2.3 Ammonia; 5.2.4 Hydrogen; 5.2.5 Nitric Oxide; 5.2.6 Nitrogen Dioxide; 5.2.7 Other Gases; 5.3 Humidity Sensors; 5.4 Cation Detection; 5.5 Anion Detection.