Catalytic Application of Nano-Gold Catalysts PDF
Preview Catalytic Application of Nano-Gold Catalysts
Catalytic Application of Nano-Gold Catalysts Edited by Neeraj Kumar Mishra Catalytic Application of Nano-Gold Catalysts Edited by Neeraj Kumar Mishra Published by ExLi4EvA Copyright © 2016 All chapters are Open Access distributed under the Creative Commons Attribution 3.0 license, which allows users to download, copy and build upon published articles even for commercial purposes, as long as the author and publisher are properly credited, which ensures maximum dissemination and a wider impact of our publications. After this work has been published, authors have the right to republish it, in whole or part, in any publication of which they are the author, and to make other personal use of the work. Any republication, referencing or personal use of the work must explicitly identify the original source. As for readers, this license allows users to download, copy and build upon published chapters even for commercial purposes, as long as the author and publisher are properly credited, which ensures maximum dissemination and a wider impact of our publications. Notice Statements and opinions expressed in the chapters are these of the individual contributors and not necessarily those of the editors or publisher. No responsibility is accepted for the accuracy of information contained in the published chapters. The publisher assumes no responsibility for any damage or injury to persons or property arising out of the use of any materials, instructions, methods or ideas contained in the book. Publishing Process Manager Technical Editor AvE4EvA MuViMix Records Cover Designer ISBN-10: 953-51-2641-5 ISBN-13: 978-953-51-2641-6 Print ISBN-10: 953-51-2640-7 ISBN-13: 978-953-51-2640-9 C ontents Preface Chapter 1 Nanoporous Gold Films as Catalyst by Sang Hoon Kim Chapter 2 Gold-Catalysed Reactions by J.A. Moma, T.A. Ntho and Michael Scurrell Chapter 3 Supported Gold Nanoparticles as Promising Catalysts by Ahmad Alshammari and Venkata Narayana Kalevaru Chapter 4 Synthesis of Gold Nanoparticles Using Amino Acids by Light Irradiation by Lilia Coronato Courrol and Ricardo Almeida de Matos Chapter 5 Electrochemical Reactivity at Free and Supported Gold Nanocatalysts Surface by Seydou Hebié, Yaovi Holade, Karine Servat, Boniface K. Kokoh and Têko W. Napporn Preface Gold, considered catalytically inactive for a long time, is now a fascinating partner of modern chemistry, as scientists such as Bond, Teles, Haruta, Hutchings, Ito and Hayashi opened new perspectives for the whole synthetic chemist community. Recently gold has attracted significant attention due to its advantageous characteristics as a catalytic material and since it allows easy functionalization with biologically active molecules. In this context, when gold is prepared as very small particles, it turns out to be a highly active catalyst. However, such a phenomenon completely disappears when the gold particle size grows into the micrometer range. Therefore, the preparation for obtaining an active gold catalyst is so important. The primary objective of this book is to provide a comprehensive overview of gold metal nanoparticles and their application as promising catalysts. Chapter 1 Nanoporous Gold Films as Catalyst Sang Hoon Kim Additional information is available at the end of the chapter http://dx.doi.org/10.5772/64081 Abstract Nanoporous gold (NPG) is reviewed as a catalyst. Various preparation methods were first reviewed for NPG and its structure. Applications of this catalyst in CO oxidation, hydrogen oxidation, hydrogen production are discussed. Regarding CO oxidation, detailed studies on reaction mechanism and density functional theory (DFT) calcula‐ tions were also reviewed. Not only as a model reaction but also practical aspects of removing CO residue in hydrogen stream are discussed. Beyond those simple reactions, the application of NPG to more complicated reactions such as alcohol oxidation is reviewed. Selective aerobic oxidation of gas‐phase alcohols is first reviewed and reactions in liquid phase are discussed. Finally, future prospects of NPG as a catalyst for more complicated reactions such as organic synthesis are briefly discussed. Keywords: nanoporous gold, catalysis, CO oxidation, hydrogen oxidation, selective oxidation of alcohol 1. Introduction Recently, nanoporous gold (NPG) films have attracted significant interest in various fields such as catalysis, sensors, optics and electrochemistry due to their high catalytic activity, high conductivity, easy modification, high stability, tuneable porosity and good biocompatibility [1]. Compared to the regular gold films which are dense inside, NPG films have sponge‐like or reticulate structures with nanometer‐sized pores throughout the body of the film. The nano‐ pores are typically 20–50 nm in size and can be as small as 5 nm depending on the preparation method (Figure 1). NPG films are typically prepared by selective etching of a less noble component from gold‐containing alloys. Early studies on NPG structures could be found as early as 1960s, but NPG structures in the studies were prepared as a model system for study‐ ing the molecular mechanism of alloy corrosion [2]. From a technological point of view, 2 Catalytic Application of Nano-Gold Catalysts researchers began to explore and develop the potential of NPG for a variety of technological applications since the late 1990s. Figure 1. Scanning electron microscopy images of nanoporous gold film (a) cross sectional and (b) top view. NPG film was prepared by dealloying of Au Ag (atom%) alloy in nitric acid. Reprinted with permission from Ref. [3]. Copy‐ 32 68 right 2001 Macmillan Magazines Ltd. The catalytic activity of gold in the nanometer scale attracted great attention, most notably, in 1987 when Haruta et al. found the unexpected exceptional catalytic activity of nanometer‐sized gold nanoparticles for CO oxidation even at below room temperature [4]. Before this discovery, gold was largely known to be very stable and inert. Bulk gold is a precious metal and does not have catalytic activity. Since then, numerous studies have been devoted to unravelling the catalytic properties of gold nanoparticles [5]. At the same time, immobilizing gold nanoparti‐ cles on a suitable support was gaining significance as it was apparent that they should be fixed somewhere to be used as a catalyst. Typically, carbon‐derived materials such as carbon nanotubes and glassy carbon were used as support [6]. However, it was one of the intrinsic problems that immobilized gold nanoparticles were being detached from the support during reaction and it caused degradation of the catalytic activity of gold nanoparticle‐supported composite catalyst. NPG plays a role in this aspect as it is a one‐body film and there was no concern regarding the loss of catalyst materials [7]. Consequently, the catalytic activity of the NPG films drew considerable attention from the late 1990s. CO oxidation was the first model reaction tested using NPG as was the case for gold nanoparticles.
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