This document is downloaded from DR‑NTU (https://dr.ntu.edu.sg) Nanyang Technological University, Singapore. Exploring layered metal chalcogenides : electrochemistry and application Chia, Xinyi 2018 Chia, X. (2018). Exploring layered metal chalcogenides : electrochemistry and application. Doctoral thesis, Nanyang Technological University, Singapore. https://hdl.handle.net/10356/102528 https://doi.org/10.32657/10220/47379 Downloaded on 09 Oct 2021 12:42:47 SGT ELECTROCHEMISTRY AND APPLICATION AND ELECTROCHEMISTRY CHALCOGENIDES METAL LAYERED EXPLORING EXPLORING LAYERED METAL CHALCOGENIDES – - ELECTROCHEMISTRY AND APPLICATION CHIA XINYI CHIA XINYI SCHOOL OF PHYSICAL & MATHEMATICAL SCIENCES NANYANG TECHNOLOGICAL UNIVERSITY 2018 2018 EXPLORING LAYERED METAL CHALCOGENIDES – ELECTROCHEMISTRY AND APPLICATION CHIA XINYI School of Physical and Mathematical Sciences A thesis submitted to the Nanyang Technological University in partial fulfillment of the requirement for the degree of Doctor of Philosophy 2018 Acknowledgement My experience in the four years of PhD studies is reminiscent of the themes in my favourite novel – The Alchemist by Paulo Coelho. There is a quote from the novel that rings true for me, “And, when you want something, all the universe conspires in helping you to achieve it.” I thank God, Father of the Universe, for granting me the courage to embark on this PhD course, and also for the strength to see it through. Certainly, the completion of this thesis would not have been possible without the encouragement, kindness and love from the people that He has blessed me with in this four-year journey. My profound gratitude goes to my thesis advisor Professor Martin Pumera for his steadfast support, guidance and dedication. I am very privileged to have a supervisor who brings out my potential and confers many opportunities to explore, learn and grow as a scientist. His zealous attitude, brilliant scientific acumen and optimism towards research have in countless ways shaped my perspectives in science and in life. Most unforgettable was when I first joined the group as an undergrad; I was then overly concerned about the experimental results, he reassured me, “Don’t worry. If it fails, move on and try the next thing.” His words resonated with me: guiding me in my research and helping me overcome my fear of failure. Now what scares me is no longer the fear of failing. It is that I have never tried. He has imparted to me many lessons – to persevere, to be curious and to stay thrilled by the science you discover because at a given point, you are the only person in the world who knows something new. I would like to extend my gratitude to the University for awarding me with the Nanyang President Graduate Scholarship. Apart from granting me the financial freedom to perform research at NTU, the scholarship has also brought me to various international conferences where I presented my work and engaged in fascinating discourse with distinguished scientists and even had meals with Nobel Laureates. These experiences have enriched my PhD life. I would like to acknowledge Prof Zdeněk Sofer and his team from the University of Chemistry and Technology in Prague for the material synthesis. I am thankful to have them as my collaborators. I would like to thank Professor Jason England for agreeing to assume the role as my new supervisor after Prof Pumera’s departure. Prof England’s kindness and prompt action provided a smooth transition for me especially when managing administrative details pertaining to graduation. i I would also like to express my sincere gratitude to Dr Adriano Ambrosi for his mentorship and advice. I am impressed by his spontaneity in generating ideas during our discussions that presented me with interesting insights on my projects. In addition, I am indebted to my seniors, especially Alex, for their gracious sharing of technical knowledge and laboratory expertise that equipped me with the groundwork skills. Beyond that, Alex taught me the humility of wisdom. When approaching him for help, he has never once put me down. Words cannot do justice to my appreciation towards his great patience and kindness. I am both humbled and inspired by the dynamism of the Pumera group that cultivated a friendly and conducive environment for my learning. Despite having members of 10 different nationalities amongst us, the collective experiences in-lab as well as out-of-lab (over lunch, excursions and badminton) forged strong friendships and collaborations; ties that bind us through weddings, kids, career transitions and even moves across continents. I would like to express my appreciation to all members of the Pumera group – Adriano, Alessandra, Bahareh, Carmen, Rui, Stanislav, CK, Lu, Adeline, Alex, Colin, Wei Zhe, Hong, Rou Jun, James, Shu Min, Zafir, Naziah, Chee Shan, Xing Juan, Yong, Lei, Farhanah, Tijana, Nasuha, Hui Ling and Yi Heng for the amazing camaraderie and for adding an extra sparkle in my, otherwise ordinary, postgrad life. Special mention goes to Hong, Shu Min and Naziah, who have seen me through the years, for all our heart-to-heart conversations and for being there when I need a listening ear. I would also like to acknowledge Ayu, who was my FYP undergrad student, for her contribution in my research and for her confidence in me as her mentor. My heartfelt appreciation goes to my family for their unconditional love, support and the sacrifices made. My parents have always understood how important this thesis means to me and they do all that they can to support me in their every step and action. Always my cheerleader, my sister Xintian has been my source of inspiration to be ambitious, to be bold even in the face of uncertainties, to chase my dreams and to reach for the sky. Thank you Daddy, Mummy and Xintian for being my pillar of strength, love and support, I could not have done it without you. Finally, I would like to thank the love of my life Timothy who has been there at every step of the way, providing me with a love so precious and helping me to live life to the fullest. Two are better than one; thank you for being my supportive and able partner as we journey through this marathon called life ♥ ii Table of Contents Page Acknowledgement .......................................................................................................... i Table of Contents .......................................................................................................... iii Summary ........................................................................................................................ v List of Publications ....................................................................................................... vii Thesis Organisation ........................................................................................................ x Chapter 1: Objectives of the Thesis ............................................................................... 1 Chapter 2: Introduction ................................................................................................. 8 2.1 The Energy Conundrum ...................................................................................... 10 2.2 Living the Hydrogen Dream and the Challenge .................................................. 11 2.3 Towards a Suitable Catalyst: Layered Metal Chalcogenides ............................... 14 Chapter 3: Background and Literature Review ............................................................ 22 3.1 Application of Layered Metal Chalcogenides: Hydrogen Evolution Reaction .... 24 3.2 Electrochemistry of Layered Metal Chalcogenides ............................................ 25 3.3 Factors Influencing Electrochemical Hydrogen Evolution Reaction of Layered Metal Chalcogenides ................................................................................................ 30 3.4 Strategies to Enhance Hydrogen Evolution Performance of Layered Metal Chalcogenides ................................................................................................ 35 Part I: Electrochemistry of layered metal chalcogenides and trends Chapter 4: Electrochemistry of Group 5 Transition Metal Dichalcogenides ............... 55 Chapter 5: Electrochemistry of Transition Metal Ditellurides: CoTe2 and NiTe2 ........ 112 Chapter 6: Electrochemistry of an Anti-MoS2 Structure Metal Chalcogenide: Tl2S………………………….. ................................................................................................ 146 Chapter 7: Electrochemistry of Tin Chalcogenides: SnS versus SnS2 ......................... 189 Part II: Strategies tailoring electrocatalytic efficiency of transition metal dichalcogenides for hydrogen evolution Chapter 8: Group 5 Transition Metal Doped WSe2 for Electrocatalysis ..................... 235 Chapter 9: Porous MoSex Structures for Electrocatalysis .......................................... 277 Chapter 10: Pt-MoSx Hybrid Electrocatalysts ............................................................. 317 Chapter 11: Electrochemical Tuning of Group 6 Transition Metal Dichalcogenides for Electrocatalysis ........................................................................................................... 360 Chapter 12: Conclusion and Epilogue ........................................................................ 413 iii iv Summary Layered metal chalcogenides have garnered considerable attention in recent years due to their vast array of applications. This class of materials was catapulted to fame by MoS2, a prominent