University of Connecticut Masthead Logo OpenCommons@UConn Doctoral Dissertations University of Connecticut Graduate School 4-15-2019 Design of Transition Metal Oxide and Phosphide Nanomaterials: Their aC talytic Activities Md Mahbubur Rahman Shakil University of Connecticut - Storrs, [email protected] Follow this and additional works at: https://opencommons.uconn.edu/dissertations Recommended Citation Shakil, Md Mahbubur Rahman, "Design of Transition Metal Oxide and Phosphide Nanomaterials: Their aC talytic Activities" (2019). Doctoral Dissertations. 2096. https://opencommons.uconn.edu/dissertations/2096 Design of Transition Metal Oxide and Phosphide Nanomaterials: Their Catalytic Activities Md Mahbubur Rahman Shakil, Ph. D. University of Connecticut, 2019 This thesis is focused on developing transition metal-based oxide and phosphide nanomaterials for catalytic application in energy conversion and the organic transformation reaction. The research projects presented in this thesis are: (1) the design and synthesis of transition metal doped ZnO catalysts for the oxygen reduction reaction (ORR), (2) the development of mesoporous FeP and CoP materials as hydrogen evolution reaction (HER) catalysts for electrochemical water splitting, and (3) the fabrication of different ZnO morphologies for coumarin synthesis by the Knoevenagel condensation. The first chapter describes the significance and background of the three research projects. We emphasize the current challenges in developing HER and ORR catalysts for water electrolysis and fuel cell application. Additionally, the importance of coumarins and challenges in their synthesis via the Knoevenagel condensation is included in this chapter. The second chapter contains the synthesis and characterization of transition metal (Mn, Fe, Co, and Ni) doped ZnO nanocrystals. The goal of this study is to develop ZnO based low-cost ORR catalysts. Single-doped and multi-doped transition-metal ZnO samples are synthesized to investigate the effects of doping in the ZnO structure and their activities for ORR. The ORR Md Mahbubur Rahman Shakil – University of Connecticut, 2019 activity of the ZnO samples is governed primarily by the oxygen vacancies created as a result of the incorporation of dopant elements. The third chapter is comprised of developing mesoporous FeP and CoP nanomaterials as an efficient HER catalyst. A noble approach, the inverse micelle sol-gel method, is utilized to synthesize mesoporous FeP, Co-FeP, CoP, Ni-CoP, and Ni-CoP/CNT materials. The mesoporosity and HER activity of the materials are monitored with the dopants and CNT support. The HER activity of the catalysts predominantly alters with the charge-transfer capabilities of the materials. The fourth chapter includes the preparation of different ZnO morphologies as catalysts for coumarin synthesis. The ZnO properties of different morphologies and their catalytic activities for coumarin synthesis by the Knoevenagel condensation reaction are examined. Catalysts synthesized using methanol show the highest activity. The enhanced activity of the ZnO synthesized in methanol is attributed to the combined effects of relatively high surface area, pore volume, and pore sizes of the materials. Design of Transition Metal Oxide and Phosphide Nanomaterials: Their Catalytic Activities Md Mahbubur Rahman Shakil B. Sc., University of Dhaka, 2006 M. S., University of Dhaka, 2008 A Dissertation Submitted in Partial Fulfilment of the Requirement for the Degree of Doctor of Philosophy at the University of Connecticut 2019 i Copyright by Md Mahbubur Rahman Shakil 2019 ii APPROVAL PAGE Doctor of Philosophy Dissertation Design of Transition Metal Oxide and Phosphide Nanomaterials: Their Catalytic Activities Presented by Md Mahbubur Rahman Shakil, B.Sc., M.S. Major Advisor…………………………………………………………………………………….. Steven L. Suib Associate Advisor…………………………………………………………………………………. Alfredo Angeles-Boza Associate Advisor…………………………………………………………………………………. Gaël Ung University of Connecticut 2019 iii Dedicated to My Parents iv Acknowledgements I would like to express my deepest gratitude to my advisor Dr. Steven L. Suib for his guidance, encouragement, and continuous support throughout my graduate studies. I would also like to thank my associate advisors Dr. Alfredo Angeles-Boza, Dr. Jing Zhao, Dr. Gaël Ung, and Dr. Fatma Selampinar for their advice, support, and encouragement during my graduate career. In addition, I am so grateful to Dr. Howell for her support and encouragement from the first day of my graduate life. I would like to thank Mrs. Bonnie Suib for encouragement and hospitality. I acknowledge Dr. Galasso for his help in a project and continuous encouragements about research. I would like to express my sincere thanks and gratitude to Dr. Seraji for his many many helps and constant inspiration in my entire graduate life. I am also thankful to Drs. Lakhsitha, Sourav, Curt, Niluka, Tahereh, Miao, and Wei. My appreciation also goes to Andrew, Yang, John, Alireza, Peter, Shanka, Junkai, Jacob (my undergrad), and all present and past Suib group members. I am thankful to the Department of Chemistry and Physics for the teaching assistantships in my graduate career. I am grateful to all employees (teaching instructors, lab technicians) of the departments for their help and support. I would like to acknowledge the U.S. Department of Energy for their financial support of my research. I would like to express my heartiest gratitude to my wife, Habiba Tasnim and our loving son, Talha for being patient with me and their continuous support for everything. Finally, I would like to express my special thanks to my parents for their unconditional and endless support, love and all continuous efforts for me from day one to till today. v Table of Contents CHAPTER 1. INTRODUCTION……………………………………………………………….1 1.1 Overview…………………………………………………………………………………....1 1.2 Background of this Research…………………………………………………………….....2 1.2.1 Transition Metal-Doped (Mn, Fe, Co, and Ni) ZnO Catalysts for the Oxygen Reduction Reaction…………………………………………………………………...2 1.2.2 Mesoporous Transition Metal Phosphides (FeP, CoP, and their TM-doped analogs) for the Hydrogen Evolution Reaction……………………………………….6 1.2.3 Synthesis of Various Morphologies of ZnO for Coumarin Synthesis via the Knoevenagel Condensation Reaction…………………………………………...........12 References……………………………………………………………………………………..14 CHAPTER 2. SINGLE-DOPED AND MULTIDOPED TRANSITION METAL (Mn, Fe, Co, AND Ni) ZnO AND THEIR ELECTROCATALYTIC ACTIVITIES FOR OXYGEN REDUCTION REACTION……………………………………………………………………24 2.1 Overview…………………………………………………………………………………...24 2.2 Introduction………………………………………………………………………………...25 2.3 Experimental Section………………………………………………………………………27 2.3.1 Chemicals…………………………………………………………………………….27 2.3.2 Materials Synthesis…………………………………………………………………...27 2.3.3 Materials Characterization…………………………………………………………...27 2.3.4 Electrochemical Measurements ……………………………………………………...29 vi 2.4 Results……………………………………………………………………………………...29 2.4.1 XRD Analysis………………………………………………………………………...29 2.4.2 Surface Morphology and Surface Area Analysis……………………………………..31 2.4.3 Chemical Composition Analysis……………………………………………………..34 2.4.4 XPS Analysis…………………………………………………………………………35 2.4.5 EPR Analysis………………………………………………………………………...40 2.4.6 Optical Analysis (Raman and Photoluminescence Spectroscopy)……………………41 2.4.7 ORR Activity Evaluation of the Synthesized ZnO Samples…………………………44 2.5 Discussion …………………………………………………………………………………48 2.5.1 Phase Identification of the Materials………………………………………………….48 2.5.2 Surface Morphology of the Materials………………………………………………...49 2.5.3 Presence of Dopants in the Synthesized Materials……………………………………49 2.5.4 Oxidation States of the Dopants within the Materials………………………………...50 2.5.5 Location and Co-ordination of Dopants within the Materials………………………...52 2.5.6 Phase Purity of Synthesized ZnO Materials and the Presence of Defects……………..52 2.6. Conclusions………………………………………………………………………………...55 References………………………………………………………………………………………56 CHAPTER 3. TRANSITION METAL (Co & Ni) DOPED MESOPOROUS CoP AND FeP NANOMATERIALS FOR THE HYDROGEN EVOLUTION REACTION………………64 3.1 Overview…………………………………………………………………………………...64 3.2 Introduction………………………………………………………………………………...65 3.3 Experimental Section………………………………………………………………………67 vii 3.3.1 Chemicals…………………………………………………………………………….67 3.3.2 Synthesis of Mesoporous Fe3O4, 5 % Co -Fe3O4 and Co3O4, 5 % Ni-Co3O4 and 5 % Ni-Co3O4 / CNT)……………………………………………………………………..67 3.3.3 Synthesis of Mesoporous FeP, 5 % Co-FeP and CoP, 5 % Ni-CoP, 5 % Ni-CoP/ CNT Catalysts…...................................................................................................................68 3.3.4 Characterization……………………………………………………………………...69 3.3.5 Electrochemical Measurements………………………………………………………70 3.3.5.1 Working Electrode Preparation………………………………………………70 3.3.5.2 Electrochemical Tests………………………………………………………...70 3.4 Results……………………………………………………………………………………...71 3.4.1 Crystalline Structure of Mesoporosities of Oxide Precursors ……………………….71 3.4.2 Characterization of Phosphide Materials…………………………………………….75 3.4.3 HER Performance of the Synthesized Mesoporous Phosphide Materials…………...88 3.4.3 Stability of Mesoporous FeP Catalyst………………………………………………..92 3.5 Discussion………………………………………………………………………………….93 3.6 Conclusions………………………………………………………………………………...98 References………………………………………………………………………………………98 CHAPTER 4. SYNTHESIS OF ZnO WITH DIFFERENT MORPHOLOGIES: THEIR CATALYTIC ACTIVITIES TOWARD COUMARIN SYNTHESIS VIA THE KNOEVENAGEL CONDENSATION REACTION………………………………………..108