九州大学学術情報リポジトリ Kyushu University Institutional Repository Fundamental Study on Structural and Surface Control on Single Crystalline Metal Oxide Nanowires 趙, 茜茜 https://hdl.net/2324/4496082 出版情報：Kyushu University, 2021, 博士（工学）, 課程博士 バージョン： 権利関係： Fundamental Study on Structural and Surface Control on Single Crystalline Metal Oxide Nanowires (単結晶金属酸化物ナノワイヤの微細構造・表 面構造制御に関する基礎的研究) XIXI ZHAO Ph. Thesis September 2021 Fundamental Study on Structural and Surface Control on Single Crystalline Metal Oxide Nanowires A DISSERTATION SUBMITTED TO INTERDISCIPLINARY GRADUATE SCHOOL OF ENGINEERING SCIENCE, KYUSHU UNIVERSITY IN PARTIAL FULFILLMENT OF REQUIREMENTS FOR THE DEGREE OF DOCTOR OF PHILOSOPHY IN ENGINEERING XIXI ZHAO September 2021 ii Abstract Abstract Metal oxide nanowires are promising building blocks for various applications due to their unique physical and chemical properties. Among various nanowire growth methods, a hydrothermal method is particularly promising because the process can be performed at relatively low temperatures (<100 oC). Although efforts have been made to investigate a synthesis and control of hydrothermal single crystalline metal oxide nanowires, there are still challenging and interesting issues as to the controllability of nanowire size distributions and the surface modification and functionalization.
In chapter I, the general introduction for this thesis is described. In chapter II, the related literature review is given to explain the research background of this thesis and the comparison with existing knowledge. In chapter III, I demonstrate the effect strategy of excessive ammonia addition to significantly increase on the growth rate of ZnO nanowires. We found that the ammonia addition substantially narrows the width of “concentration window”.
The narrowed “concentration window” and the resultant increased growth rate by the ammonia addition can be understood in terms of synchronized effects of both (1) a reduction of zinc hydroxide complex (precursor) concentration and (2) a fast rate limiting process of ligand exchange between different zinc complexes. The present knowledge of “concentration window” will accelerate further tailoring an anisotropic crystal growth of hydrothermal ZnO nanowires. In chapter IV, I demonstrated a facile, rational method to synthesize monodispersed sized zinc oxide (ZnO) nanowires from randomly sized seeds. Uniformly shaped nanowire tips constructed in ammonia-dominated alkaline conditions serve as a foundation for the subsequent formation of the monodisperse nanowires.
By precisely controlling the sharp tip formation and the nucleation, our method substantially narrows the distribution of ZnO nanowire diameters. The proposed concept of sharp tip based monodisperse nanowires growth can be applied to the growth of diverse metal oxide nanowires and thus paves the way for bottom-up grown metal oxide nanowires-integrated nanodevices with a reliable performance. In chapter V, I demonstrated an emergence of a thermally robust molecular selectivity with one i Abstract carbon resolution for aliphatic chains of aldehydes on molecularly templated single crystalline ZnO nanowire surfaces with amorphous TiOx shell layers grown by atomic layer deposition. Spectroscopic, spectrometric and microstructural measurements revealed that such molecular selectivity only emerged when controlling the number of atomic layer deposition cycles with anchoring spatially isolated target-aliphatic aldehyde molecules on the ZnO surface during shell layer formations.
This present method to create thermally robust molecular selectivity on abundant oxide surfaces is shown to be simple and highly reproducible and holds promise for scalability and applicability to various molecules. In chapter VI, I summarize overall conclusions in this PhD thesis. ii Acknowledge Acknowledgement First and foremost, I wish to express my sincere gratitude to Prof. Takeshi Yanagida of the Institute for Materials Chemistry and Engineering, Kyushu University; Department of Applied Chemistry, School of Engineering, The University of Tokyo, for his continuous encouragement, supports and stimulating discussions.
His sophisticated and exquisite viewpoints always led me to be one step ahead. I sincerely express my gratitude to Prof. Hata and Prof. Hojo for their invaluable comments and constructive suggestions.
Then, I deeply express my gratitude to Assoc. Kazuki Nagashima for his lots of encouragement, supports, invaluable discussions, and constructive suggestions. I learned the scientific knowledge, the experimental procedures, the perspectives, and the interests of research from him, especially his ability to be logically rigorous in making presentations. I would like to express my appreciation to Assis.
Takuro Hosomi for his ideas and explanation during the discussion. His extensive knowledge covering the physical and chemistry field always gives me a new understanding to research. I would like to express my sincere gratitude to Assoc. Without his helpful guidance and support, it would be difficult for me to comprehensively understand our experiment and equipment.
I would like to express my appreciation to Dr. Masaki Kanai for lots of theory discussion and guidance in the experiment. I learned systematic knowledge in the semiconductor field, but I also learned the importance of a rigorous scientific attitude. iii Acknowledge I would like to express my appreciation for all staff in Yanagida Lab.
Especially, I would like to thank Prof. Wataru Tanaka, Dr. Guozhu Zhang, Dr. Benjarong Samransuksame, Dr.
Hao Zeng， and Dr. Jiangyang Liu for their support and encouragement. I would like to thank Ms. Hiroki Imaizumi, she helped me a lot in both life and work, especially with the application for the nursery school.
And thanks to Ms. Maki Inoue as well. I acknowledge all the alumni in Yanagida Lab, including Prof. He Yong, Prof.
Gang Meng, Prof. Fuwei Zhuge, Mr. Hiroshi Anzai, Dr. Zetao Zhu, Dr.
Chen Wang, Dr. Ruolin Yan, Mr. Hiroki Yamashita, Mr. Yuki Nagamatsu, Mr.
Kentaro Nakabayashi, Mr. Yuya Akihiro, Mr. Junxiong Zhang, Ms. Mengke Pei, Mr.
Sameh Okasha, Mr. Daiki Sakai, Mr. Akihide Inoue, Ms. Chie Nakamura, Dr.
Yosuke Hanai, Mr. Rimon Yanaguchi, Mr. Masahiro Shimizu, Mr. Satoru Shiraishi and Dr.
I would like to thank the Japan Society for the Promotion of Science (JSPS) for financial support. I would like to thank my family for their support and understanding of my career. Especially, my husband, I am thanking him for his support and help in my work and life. I would thank my son (Bohao Zhu).
I am thanking him for understanding and supporting me all the time. Finally, I appreciate all the kind people during my Ph. XIXI ZHAO iv Acknowledge iv Contents Contents Abstract. iii Chapter I General Introduction.1 Metal Oxide Nanowires .3 Nanowires Based Molecular Recognition Surface .4 Significance of This Study .2 Framework of This Thesis.
5 Chapter II Literature Reviews .2 Synthesis of Metal Oxide Nanowires .3 Control of the Nanowire Structure .1 Nanowire Size Control.2 Nanowire Morphology Control.3 Nanowire Position Control .4 Nanowire Orientation Control .5 Nanowire Density Control .4 Metal Oxide Nanowires for Molecular Recognition .5 Modifications of Nanowire Surface .1 Doping/Loading of Noble Metals/Oxides on Nanowire Surface .2 Molecular Assemble on Nanowire Surface .3 MOF Coated Modification on Nanowire Surface .4 Molecular Imprinting on Nanowire Surface. 21 Chapter III Substantial Narrowing on the Width of “Concentration Window” of Hydrothermal ZnO Nanowires via Ammonia Addition .4 Results and Discussions. 54 Chapter IV Synthesis of Monodispersedly Sized ZnO Nanowires from Randomly Sized Seeds .4 Results and Discussions. 75 Chapter V Molecularly Templated Metal Oxide Surface Discriminates Length of Aliphatic Chains with Long-Term Thermal Robustness .4 Results and Discussions.
109 Chapter VI Overall Conclusions. 126 List of Publications. 138 vi Chapter I General Introduction General Introduction 1.1 Metal Oxide Nanowires Due to the advantages of larger surface area,1 grain boundary-free,2 structural design flexibility,3 good thermal and chemical stability4 and diversity of functional properties,5 single-crystalline metal oxide nanowires are promising candidate materials for electronics,6 energy harvest,7 molecular recognition,8 and human interaction.9 Various bottom-up methods based on natural crystallization processes have been well developed to grow single-crystal metal oxide nanowires, such as gas-phase and solution-phase methods.10 Although the gas- phase methods can produce high-quality single-crystal nanowires, the high temperature with more than 600 oC is often required, which is a limitation to grow nanowires on the thermal-unstable substrates.11 In contrast, the solution-phase method can grow high-quality single-crystalline nanowires even at low temperature below 100 o C.10 Especially, the hydrothermal method is widely used to synthesize various metal oxide nanowires, including ZnO, SnO2, WO3, and so on.12,13 Furthermore, this easy-to-operate method with a low cost enables nanowire growth on a large-scale substrate through an environmentally friendly process. In addition, the structural and morphological control of nanowires can be conducted by adjusting the growth parameters, such as growth time, growth temperature, and solution concentration.
Since the structure of nanowires can undoubtedly affect their physical and chemical properties, the designed growth of nanowires by hydrothermal method provides a novel approach to enhancing the performances in various electronic, magnetic, optical and, thermal applications.2 Molecular Recognition The molecular recognition is often likened to a “lock “and “key”, which involves interactions between host and guest molecules, such as noncovalent interactions, including Van der Waals forces, hydrogen bonds, π-π interactions, coordinate bonds, and electrostatic force.17,18,19,20 Because of their high selectivity for target molecules, molecular recognition-based separation and sensing systems have gained much attention in the field of disease diagnosis,21 health monitoring,22 environmental monitoring,23 security checking,24 drug delivery,25 and so on. Currently, there are three main types of detection instruments based on molecular recognition: 1) Mass Spectrometry (high resolution but needs more extended analysis time);26 2) Optical methods (high resolution but 2 General Introduction only apply to small target molecules);27 3) Sensors (small size and portable but limited detection targets and low selectivity).28 Considering the advantages of miniaturized sensors, including portability, high sensitivity, and fast response, they are one of the most promising next generation instruments based on molecular recognition technology in our further life.3 Nanowire Based Molecular Recognition Surface The diverse demand in the molecular recognition and separation process has accelerated related science and technology development. Current advances in nanotechnology have greatly facilitated the further improvement of the performance of a device due to its dimension in the nanoscale range, which exhibits unique properties compared to bulk materials.30 Among the various nanomaterials proposed to develop sensor devices, and metal oxide nanowires have attracted great interest due to their excellent single crystallinity, well-defined crystal orientations, high surface-to-volume ratio, and specific physicochemical properties.31 Significant efforts have been made to enhance the performance of metal oxide nanowires-based molecular recognition devices in the past years.32 People found that identifying specific molecules can be achieved by two approaches of 1) design the growth of the nanowires, including expanding nanowire material species, growing specific crystal face of nanowires, controlling the morphology of size, uniformity, orientation, and density of nanowires; 2) surface functionalization on nanowires, including doping of metal/oxides on surface, molecular assemble on the surface, MOF coated on surface, and molecular imprinting on the surface.4 Significance of This Study As mentioned above, metal oxide nanowires fabricated by the hydrothermal method provide ideal platforms for constructing molecular recognition surfaces, which can be utilized in sensor and other device applications. However, there are still many problems in creating a novel nanowire-based structure for molecule recognition so far.
Firstly, the nanowire growth mechanism is not well developed. For example, the limitation of zinc concentration in nanowire growth and selective anisotropic growth emerges with a certain concentration range. These result in the slow 3 General Introduction nanowire growth rate at optimal Zn concentration, how to dramatically increase the growth rate of nanowires? Although we found many factors can precisely control the morphology of nanowires, once the seed layer is not uniformly distributed, it is very hard to reduce the size distribution of fabricated nanowires. How to control the uniformity of the nanowire diameter without using the expensive lithography process? Secondly, the selectivity to target molecules of molecular recognition elements is dependent on their intrinsic properties of materials.
In this case, the targets that can selectively interact with materials are limited, and the selectivity is not enough. Therefore, how to design a conceptual approach to create a novel type of recognition surface adapted to a large number of targets. From the above description, this thesis is focused on the fundamental study of nanowire growth, control of the nanowire growth, and conceptual creation of a novel nanowire-based recognition surface.