18 January 2021, Beijing
Preface
Throughout the history of human science and technology development, the surge of new technology is always accompanied by the discovery and improvement of new materials. From the ancient bone, stone, porcelain, metal materials to the modern high-performance plastics, alloys, micromaterials, and nanomaterials, which are still developing constantly, all of them have left a deep imprint in the history of human development. Compared with the traditional crystalline materials with a periodic arrangement of basic units, amorphous materials are of short-range-ordered and long-range-disordered structure. Unlike crystalline counterparts, amorphous materials do not have grain boundaries, crystal defects, segregation, and anisotropy, so amorphous materials show macroscopic homogeneity and isotropy. For example, amorphous alloys have a unique disordered structure similar to glass. They share the characteristics of both metal and glass and thus have unique physical, chemical, and mechanical properties. In the aspect of mechanical strength, amorphous alloys have high strength, high hardness, high wear and corrosion resistance, high fatigue resistance, low elastic modulus, and large elastic strain limit, which is considered to have a broad potential application in the field of engineering mechanics, biomedical science, and aerospace. In addition to mechanical properties, amorphous materials have also attracted wide attention because of their highly unsaturated centers on the surface and homogeneous catalytic centers in chemical and structural environments, which make them not only as model catalysts but also as the practical ones.
In addition, the emergence of nanomaterials has been one of the most important developments in the field of materials since the late twentieth century. Nanomaterials refer to a new class of functional materials in which at least one dimension of materials is reduced to the nanoscale. Because their characteristic size is similar to the De Broglie wavelength of electrons, the electron movement in this kind of materials is limited, and their energy is changed from continuous state to discontinuous energy level, thereby deriving many new physical and chemical properties, which have been widely concerned by the scientific community. In recent years, nanoscaled amorphous materials have gradually entered people’s field of vision and shown their excellent performance comparable to or even better than that of crystalline nanomaterials in various fields, such as catalysis, electrochemical energy storage, mechanical engineering, and so on.
Although many studies have verified the broad application prospects of amorphous nanomaterials as emerging materials in many fields, their development is still in its infancy, and many scientific and technical problems need to be solved. For example, amorphous materials are widely believed to have short-range order, but their atomic arrangement forms are still unable to be accurately defined even with the development of electron microscopy techniques today. Besides, it is difficult to control the growth mode of amorphous materials and obtain specific structures with regular morphology because of their long-range-disordered internal structure. A single preparation method can only obtain amorphous nanomaterials with specific structures, which is far from satisfying the research on the performance regulation of amorphous materials. In addition, the atomic disorder in amorphous materials affords a large number of unsaturated centers. In theory, these abundant active sites should have higher catalytic performance than those of crystal nanomaterial in an order of magnitude, but the existing studies have not been realized yet.
This book was written based on guaranteeing the integrity of the content, combined with my experience in the preparation of amorphous nanomaterials, characterization, and application research practice for many years, not only expounds the latest information of amorphous nanomaterial preparation technology and cutting-edge progress, but also take into account some applications of amorphous nanomaterials. This book focuses on the elaboration of research ideas and methods, aiming to enable readers to have a full understanding of amorphous nanomaterials, and easy to grasp the preparation principle, application range, and existing technical bottlenecks, so as to better carry out innovative research in the future. This book is divided into 13 chapters, the main contents of each chapter are written as follows: Chapter 1 mainly introduces the intrinsic characteristics, development history, and general preparation methods of amorphous nanomaterials; Chapters 2 and 3 introduce the local structure, electronic states, and defects of amorphous nanomaterials, mainly from the perspective of characterization techniques. In Chapters 4–7, the latest progress of preparation methods of 0D–3D amorphous nanomaterials is mainly introduced. In Chapter 8, the main ways and structural characteristics of hybrid nanomaterials, such as amorphous coating or doped nanomaterial, are introduced. Chapters 9–13 describe the applications of amorphous nanomaterials in catalysis, electrochemical energy storage, and mechanical engineering.
I would love to express my special thanks to my group members who have contributed to the scientific research and in the process of book writing and revision: Wei Zhou, Guangsheng Wang, Hua Wang, Yujie Zhu, Xiaotian Wang, Lidong Li, Jianxin Kang, Zhao Yang, Xiaoyi Qiu, Jie Yang, Zhi Cai, Baohong Zhang, Binbin Jia, Jian Yu, Yan Zhang, Juzhe Liu, Xiaogang Niu, Leqing Deng, Xiangyu Chen, Fengshi Li, Hewei Zhao, Jianwei Nai, etc. Besides, I would also like to thank Prof. Yongjun Tian, Prof. Xiaodong Han, Prof. Xun Wang, Prof. Zhiyong Tang, Prof. Jing Zhang, Prof. Yi Luo, Prof. Shihe Yang, Prof. Xiangfeng Duan, Prof. Nicholas Kotov, Prof. Limin Liu, Prof. Xiaodong Li, Prof. Lin Gu, Prof. Limin Liu, and Prof. Robert Ritchie for their great support and help in scientific research cooperation. I would also like to extend my sincere thanks to the National Natural Science Foundation of China (51532001) for its funding and support.
I would like to express my sincere thanks to Prof. Lei Jiang, Prof. Yadong Li, Prof. Hongjie Zhang, Prof. Yuliang Li, Prof. Jihong Yu, and Prof. Jinghong Li for their valuable comments and suggestions for this book. I would also like to thank the Wiley Press and editors for their enthusiastic help during the publication of this book.
This book is dedicated to those research scholars, students, and business people who are engaged in the research of amorphous nanomaterials. Because of the rapid development in the field of amorphous nanomaterials, the emergence of new knowledge and theories, and the inexperience of the author, some mistakes inevitably exist in the book. We hope that experts and readers can provide valuable suggestions for timely supplement and revision.
17 January 2021
Lin Guo
Beihang University, Beijing
1 Introduction
1.1 Introduction of Amorphous Materials
Amorphous material is a type of substance in which basic units do not exhibit long-range order (LRO) in space but maintain some ordered characteristics only in the range of several atomic scope. Different from the traditional crystalline materials with regularly arranged basic units, amorphous materials are characterized by atomic short-range (<1 nm) order and long-range (>1 nm) disorder [1]. Compared with anisotropic crystalline materials, amorphous materials exhibit macroscopic homogeneity and isotropy. Based on this internal structure, amorphous materials do not have crystal defects such as dislocations, grain boundaries, etc., which endows the amorphous materials with some excellent mechanical properties such as high strength, high hardness, high wear resistance, high fatigue resistance, etc. At the same time, amorphous surface exhibits a high degree of unsaturated atomic sites or dangling bonds, which made it desirable as a model catalyst or a practical catalyst. Thus, the special disordered surface structure can provide more active sites than traditional crystal nanomaterials and further improve the catalytic performance. Apart from that, the special atomic arrangement of amorphous structures can effectively regulate