Illustrated throughout with excellent figures, this multidisciplinary work is not just a reference for researchers in chemistry and materials science, but a handy textbook for advanced undergraduate- and graduate-level students in nanoscience- and nanotechnology-related courses, especially those with an interest in developing novel materials for advanced power systems. V476 ISBN 978-981-4669-00-9 Wang Yixuan Wang is a full professor in the College of Science and Technology at Albany State University (Albany, USA). He earned his PhD in theoretical chemistry from Shandong University in 1994 and completed postdoctoral training at the Max Planck Institute for the Physics of Complex Systems (Dresden, Germany), Ludwig-Maximilians University (Munich, Germany), and Texas A&M University (College Station, USA). Prof. Wang has published about 80 peer-reviewed journal articles, coedited one book, and contributed six book chapters. His expertise is in computational/ theoretical chemistry with applications in molecular design of nanomaterial-based drug delivery systems, noncovalent interactions of bio-nano systems, and molecular modeling and simulations of advanced power sources. His research as a principal investigator is currently supported by the National Science Foundation, the National Institutes of Health, the American Recovery Reinvestment Act, and the ACS Petroleum Research Fund. Prof. Wang has twice won the Research of the Year Award from Albany State University (2009, 2014) and the 1997 State Natural Science Award from the State Council of China. Nanomaterials for Direct Alcohol Fuel Cell Direct alcohol fuel cells (DAFCs), such as methanol and ethanol ones, are very promising advanced power systems that may considerably reduce dependence on fossil fuels and are, therefore, attracting increased attention worldwide. Nanostructured materials can improve the performance of the cathodes, anodes, and electrolytes of DAFCs. This book focuses on the most recent advances in the science and technology of nanostructured materials for direct alcohol fuel cells, including novel non-noble or low noble metal catalysts deposited on the graphene layer and metal-free doped carbon black for oxygen electroreduction reaction, Sn-based bimetallic and trimetallic nanoparticles for alcohol electro-oxidation reaction, and novel nanomaterials for promoting proton transfer in electrolytes. In addition, the book includes chapters from not only experimentalists but also computational chemists who have worked in the development of advanced power systems for decades. Nanomaterials for Direct Alcohol Fuel Cell edited by Yixuan Wang
Nanomaterials for Direct Alcohol Fuel Cell
Pan Stanford Series on Renewable Energy Volume 2 Nanomaterials for Direct Alcohol Fuel Cell editors Preben Maegaard Anna Krenz Wolfgang Palz edited by Yixuan Wang The Rise of Modern Wind Energy Wind Power for the World
Published by Pan Stanford Publishing Pte. Ltd. Penthouse Level, Suntec Tower 3 8 Temasek Boulevard Singapore 038988 Email: editorial@panstanford.com Web: www.panstanford.com British Library Cataloguing-in-Publication Data A catalogue record for this book is available from the British Library. Nanomaterials for Direct Alcohol Fuel Cell Copyright c 2017 Pan Stanford Publishing Pte. Ltd. All rights reserved. This book, or parts thereof, may not be reproduced in any form or by any means, electronic or mechanical, including photocopying, recording or any information storage and retrieval system now known or to be invented, without written permission from the publisher. For photocopying of material in this volume, please pay a copying fee through the Copyright Clearance Center, Inc., 222 Rosewood Drive, Danvers, MA 01923, USA. In this case permission to photocopy is not required from the publisher. ISBN 978-981-4669-00-9 (Hardcover) ISBN 978-981-4669-01-6 (ebook) PrintedintheUSA
Contents Preface xi 1 Advanced Anode Catalysts for Direct Alcohol Fuel Cells 1 Youjun Fan, Junming Zhang, Qingyu Li, and Jiujun Zhang 1.1 Introduction 2 1.2 Pt-Based Catalysts 3 1.2.1 Alloy Catalysts 3 1.2.2 Oxide-Doped Pt Catalysts 7 1.3 Non-Pt Catalysts 8 1.3.1 Pd-Based Catalysts 8 1.3.2 Other Non-noble Metal Catalysts 10 1.4 Support Materials for Catalysts 13 1.4.1 Nanostructured Carbon 15 1.4.1.1 Carbon nanotubes 17 1.4.1.2 Carbon nanofiber 21 1.4.1.3 Mesoporous carbon 24 1.4.1.4 Graphene 26 1.4.2 Conducting Polymers 29 1.4.3 Hybrid Supports 31 1.5 Control of Catalyst Surface Structures 35 1.6 Fundamental Understanding of Catalystic for New Catalyst Design 40 1.7 Challenges and Possible Research Directions 41 1.8 Summary 42 2 Multimetallic Nanocatalysts for Anodic Reaction in Direct Alcohol Fuel Cell 63 Jayati Datta 2.1 Introduction 64
vi Contents 2.2 Low-Temperature Fuel Cells 65 2.3 Fuel Flexibility 65 2.4 Selection of Fuels for Direct Alcohol Fuel Cell 67 2.5 Ethanol: A Green Fuel 67 2.6 Selection of Electrocatalyst Materials for Oxidation of Alcohols 68 2.7 Binary Systems Studied for DAFC 70 2.8 Catalyst Support Interaction 70 2.9 Synthesis of Nanoparticles 71 2.9.1 Chemical Route 71 2.9.2 Electrosynthesis 73 2.10 Catalysts for DEFC: A Green Technology 76 2.10.1 Nanomaterials Specially Focused on EOR Studies: Influence of Adatoms 76 2.10.2 Ternary Nanocatalysts in Acidic Medium 84 2.10.3 Multimetallic Nanocatalysts for Alkaline DEFC 86 2.10.4 Pt-Free Combinatorial Approach 90 2.11 Conclusion 98 3 Understanding Electrocatalytic Activity Enhancement of Bimetallic Nanoparticles to Ethanol Electro-oxidation Reaction 107 Yixuan Wang and Zhenfeng Xu 3.1 Introduction 108 3.2 Theoretical Methodology and Bimetallic Models 110 3.3 Adsorption and Decomposition of H 2 O 112 3.3.1 H 2 O Adsorption over Pt n M Clusters (6 and 9; M = Pt, Sn, Ru, Cu, Rh, Pd, and Re) 112 3.3.2 Decomposition of Adsorbed Water 115 3.4 Adsorption and Decomposition of Ethanol 121 3.4.1 CH 3 CH 2 OH Adsorption and Decomposition over Pt 6 M Clusters (M = Pt, Ru, and Sn) 121 3.4.2 CH 3 CH 2 OH Adsorption and Decomposition over Pt 9 M Clusters (M = Pt, Sn, and Ru) 130 3.4.3 Kinetics of Adsorption and Decomposition of CH 3 CH 2 OH 131
Contents vii 3.5 Alloying Effect on the Adsorption Energy, Energy Barrier, and Dissociation Energy 134 3.6 Conclusion 138 4 Theoretical Aspects of Gold Nanocatalyst for Ethanol and Glucose Oxidation 145 Takayoshi Ishimoto and Michihisa Koyama 4.1 General Introduction 146 4.2 Computational Details 147 4.3 Au Surface Structure in Alkaline Solution 147 4.3.1 Introduction 147 4.3.2 H 2 OandOH Adsorption Energy on Au 148 4.3.3 Adsorption Species on Au Surface in Alkaline Solution 149 4.3.4 Summary 152 4.4 Oxidation Reaction of Ethanol on Au Catalyst 153 4.4.1 Introduction 153 4.4.2 Reaction of Ethanol over Au Catalyst 153 4.4.3 Summary 155 4.5 Oxidation Reaction of Glucose on Au Catalyst 156 4.5.1 Introduction 156 4.5.2 Reaction of Glucose 156 4.5.3 Effect of Adsorbate Species on Au Surface 159 4.5.4 Summary 161 4.6 Effect of Support Materials for Au Catalyst 162 4.6.1 Introduction 162 4.6.2 Interaction between Support Materials and Au Catalyst 163 4.6.3 Glucose Oxidation Reaction on Supported Au Catalyst 165 4.6.4 Summary 168 4.7 Summary and Perspectives 168 5 Proton Transport and Design of Proton Electrolyte Membranes for Direct Alcohol Fuel Cells 177 Liuming Yan and Baohua Yue 5.1 Introduction 178 5.2 Types of PEMs 179
viii Contents 5.3 Theoretical and Experimental Method for Design of Proton Conducting Materials 180 5.3.1 Design of Proton Conducting Materials 180 5.3.2 Transport Mechanisms 182 5.3.3 Ab initio Calculations 183 5.3.4 Molecular Dynamics Simulations 184 5.3.5 NMR Techniques 185 5.3.5.1 H-bonding and proton transport 186 5.3.5.2 Diffusion coefficients 188 5.3.6 Proof-of-Concept Experiments 189 5.4 An Example 189 5.4.1 Model Molecules 190 5.4.2 DFT Calculation Method 190 5.4.3 DFT Calculation Results 192 5.4.4 MD Simulations 194 5.4.5 1 H NMR Experiments 198 5.4.6 Proof-of-Concept Experiments 204 5.5 Summary 204 6 Nanomaterials for Oxygen Reduction Reaction (ORR) 215 R. K. Singh, F. G. S. Wasim, and M. Neergat 6.1 Introduction 216 6.2 Methodology and Descriptor of Activity 217 6.2.1 Calculation of the ESA of Pt/C in Acidic Media 219 6.3 Reaction Mechanism and Thermodynamics 219 6.3.1 Pathways in Acidic Medium 219 6.3.2 Detection of Peroxide 220 6.3.3 Electrochemical Impedance Spectroscopy (EIS) 221 6.4 Fuel Cell and Single-Electrode (RDE) Polarizations 223 6.4.1 Calculation of G and E 223 6.5 Recent Developments in Nanomaterials for ORR 225 6.5.1 Precious Metal Catalysts 225 6.5.2 Core Shell (CS) Structure 228 6.5.3 Shape-Controlled Nanoparticles 230 6.5.4 Pd-Based Alloy Catalysts 235 6.5.5 Non-precious Metal Electrocatalysts (NPMCs) 236 6.6 Conclusions 239
Contents ix 7 Advances in Understanding the Effects on the Ethanol Electro-oxidation Reaction 253 Yixuan Wang 7.1 Introduction 254 7.2 PtSn, PtSnO 2, and Pt-Based Bi- and Trimetallic PtM 1 M 2 (M 1 = Sn, Ru; M 2 = Ni, Rh, Bi, and Pd) in Acidic Media 255 7.3 Effect of Alloying Degree and Size of PtSn on the Catalytic Behavior for the EER 257 7.4 Electro-oxidation of Ethanol on PtSn/C Doped by Metal Oxides (CeO 2,TiO 2 ) Electrocatalysts 258 7.5 Electrocatalytic Activity Enhancement Mechanism of PtSn to the EER in Acidic Solution 259 7.6 Effects of ph and Composition of Electrolyte on the Activity 261 7.7 Unexpected Activity of Gold (Au) to the EER in Alkaline Media 263 7.8 Extremely High Electrocatalytic Activity of Pt/Au Structure to the EER in Alkaline Media 265 7.9 Graphene, Defective Graphene, and Other Novel Nanomaterials for the EER 266 Index 277
Preface Direct alcohol fuel cells (DAFCs) are very promising advanced power systems that may considerably reduce dependence on fossil fuels and are, therefore, attracting increased attention worldwide. Nanostructured materials can significantly improve the performance of the cathodes, anodes, as well as electrolytes of DAFCs. This book focuses on the most recent advances in the science and technology of nanostructured materials for DAFCs, including novel non-noble or low noble metal catalysts deposited on the graphene layer and metal-free doped carbon black for oxygen electroreduction reaction, Sn-based bimetallic and trimetallic nanoparticles for alcohol electrooxidation reaction, and novel nanomaterials for promoting proton transfer in electrolytes. In addition, the book includes chapters from not only experimentalists but also computational chemists who have worked in the development of advanced power systems for decades. The research-and-development outlook for new DAFCs materials has also been suggested to facilitate innovation in this important area. Illustrated throughout with excellent figures, this multidisciplinary work is not just a reference for researchers in chemistry and materials science, but a handy textbook for advanced undergraduate- and graduate-level students in nanoscience- and nanotechnology-related courses, especially those with an interest in developing novel materials for advanced power systems. In Chapter 1, Drs. Youjun Fan, Junming Zhang, Qingyu Li, and Jiujun Zhang focus on the recent advancement in the anode catalysis of DAFCs, including Pt/Pd-based catalysts and other non-noble metal catalysts. They also discuss in detail the supporting materials such as carbon nanotubes (CNTs), carbon nanofibers (CNFs), mesoporous carbon, and graphene, as well as non-carbonaceous conducting polymers and hybrid supports materials. In Chapter 2,
xii Preface Dr. Jayati Datta comprehensively discusses the state-of-the-art catalyst technology for anodic oxidation of alcohols, in particular for low-temperature fuel cell application, including the catalysts designed with a multimetallic framework. A great deal of interest has arisen for DAFCs working in an alkaline environment, which allows the use of inexpensive non-platinum metal as well as transitional metals metal oxides as critical electrode component harnessing more energy and at the same time ensuring affordability ofthefuelcellsystem. In Chapter 3, Drs. Yixuan Wang and Zhenfeng Xu summarize the systematic density functional theory studies on the adsorption and decomposition of water and ethanol on Pt n M(n = 2, 3, 6, and 9; M = Pt, Sn, Ru, Rh, Pd, Cu, and Re). The results show that from both kinetic and thermodynamic viewpoints, Sn is more active to water decomposition than pure Pt and all the other investigated PtM except PtRe, which well supports the assumption of the bifunctional mechanism that an Sn site accelerates the dissociation of H 2 O. Chapter 4, a theoretical work by Takayoshi Ishimoto and Michihisa Koyama, is devoted to the mechanistic aspects of ethanol and glucose oxidation in an alkaline environment to provide insights into the direct use of biofuels in fuel cells. Au is selected as a promising catalyst alternative to Pt in an alkaline environment. In Chapter 5, Liuming Yan and Baohua Yue contribute to the proton, alcohol, and water transport mechanism, and the rational design of proton electrolyte membranes (PEMs). They thoroughly discuss a guideline to design more efficient PEMs at a molecule level. In Chapter 6, Drs. R. K. Singh, F. G. S. Wasim, and M. Neergat present the new nanomaterials, both precious and non-precious metal-based, relevant to oxygen reduction reaction (ORR). Methods for estimating the ORR product selectivity (H 2 O/H 2 O 2 )andthe electrochemical surface area (ESA) are introduced. The evolution and synthesis of the catalysts for the ORR are then discussed in detail. Overall, the investigations on ORR significantly contribute to a better understanding of the electrochemistry of nanomaterials. In Chapter 7, I primarily summarize the effects on the activity of the electrocatalyst in DAFCs, including the composition (Pt:Sn ratio), degree of alloying, roughness and size of particles, and the ph as well as characteristics of the electrolytes of DAFCs.
Preface xiii I greatly acknowledge the dedication of all the authors mentioned above. Without their effort, the project could not have been finished. My appreciation also goes to Pan Stanford Publishing. Yixuan Wang Albany, Georgia