THE SYNTHESIS AND MODIFICATION OF 2D MATERIALS FOR APPLICATION IN WATER OXIDATION CATALYSIS ________________________________________________________________________ A Dissertation Submitted to The Temple University Graduate Board ________________________________________________________________________ In Partial Fulfillment of the requirements for the Degree DOCTOR OF PHILOSOPHY ________________________________________________________________________ By Ian G. McKendry May 2017 Examining Committee: Michael J. Zdilla, Ph.D., Dissertation Supervisor, Temple University Daniel R. Strongin, Ph.D., Examining Chair, Temple University Ann M. Valentine, Ph.D., Advisory Chair, Temple University C. Jeff Martoff, Ph.D., Physics, Temple University 1 © COPYRIGHT 2017 By Ian McKendry All Rights Reserved. ii ABSTRACT THE SYNTHESIS AND MODIFICATION OF 2D MATERIALS FOR APPLICATION IN WATER OXIDATION CATALYSIS Ian G. McKendry Professor Michael J. Zdilla The unifying goal of this work is the design of a heterogeneous catalyst that can facilitate the energy intensive oxygen evolution reaction (OER) in water splitting, considered one of the ‘holy grails’ in catalytic science. In order for this process to be industrially feasible, an efficient catalyst composed of first row transition metal based materials must be used. To accomplish this, existing systems must be studied in order to determine which properties are important and subsequent creation and modification of new systems based on lessons learned must be employed. Birnessite, a 2D layered manganese dioxide, comprises the majority of the effort. In the studies leading to this work, this material was primarily studied by mineralogists with the majority focusing on structural characterization. However, the material’s moderate activity toward performing the OER has revived interest. In this work, we look to determine important species, the role dopants play in activity, and the function of the interlayer and surface chemistry. From these findings, an enhanced, earth abundant OER catalyst will be designed. iii We determine that Mn3+ in the system plays and important role in producing a catalytic species with large oxygen production capabilities. By increasing the amount of Mn3+ in the system via a simple comproportionation reaction by exposing the Mn4+ to Mn2+ ion, we increase the total turnover of birnessite 50-fold. Additionally, the addition of dopants to the system , both within and between the sheets, has a positive effect on the activity of birnessite. In particular, incorporation of cobalt into the lattice of birnessite brings the activity level on par to that of precious metal oxide catalysts due to the cobalt offering a deeper electron acceptor than in birnessite alone. In conjunction with these studies, the role of the interlayer species and catalyst confinement has demonstrated the ability to greatly enhance a catalyst’s ability to perform the OER by ordering and orienting the water around the active confined catalyst. Combining confinement effects with the cobalt-doped birnessite sheets resulted in further enhancement in the material’s OER capabilities. This system mimics that of an enzyme where the cobalt-doped birnessite sheets facilitate greater electron-hole transfer to the interlayer active site, where the confinement effects enhance electron transfer kinetics and water organization for O-O bond formation. Additionally, metal chalcogenide OER catalysts were explored with mattagamite phase cobalt pertelluride. Through the work, we determine the formation of a Te-Co-O heterostructure as the catalytically active phase, where the metallic nature of the cobalt pertelluride facilitates charge mobility between the electrode and catalyst’s cobalt oxide surface functioning as the active OER species. iv DEDICATION This dissertation is dedicated to my parents Dennis and Karen McKendry For without you, none of this would be possible v ACKNOWLEDGEMENTS I would like to dedicate this space as a thank you to my wonderful advisor, Dr. Michael J. Zdilla. If I had the ability to assemble the perfect advisor based an infinite list of extraordinary qualities, I think I would fall short of creating the advisor, chemist, and friend I was fortunate enough with which to work. The trust he bestowed on me with my projects, coupled with the patience and willingness was monumental in my development as a scientist, and I can only hope I was able to repay even just a small fraction of support. Likewise, Dr. Daniel R. Strongin has served as a close secondary throughout my graduate studies and played a key role in evolution and growth as a scientist with all kind words mentioned above for Dr. Zdilla holding equal value for Dr. Strongin. Additionally, I would like to thank my undergraduate advisor, Dr. Peter M. Graham, from Saint Joseph’s University spark that ignited the fire for scientific research. Your knowledge, encouragement, and those hours of working side-by-side in that double glovebox proudly marks the starting point of my scientific career. Some people mark themselves lucky finding one decent mentor, I was blessed enough to win the lottery three times. I would like to thank Dr. Ann M. Valentine for her advice and guidance throughout my time at Temple, and Dr. Jeff Martoff for his knowledge and experience. I am glad and thankful that both of these fine scientists could serve on my committee. I would like to thank my colleagues in the Department of Energy’s Center for the Computational Design of Layered Functional Materials (CCDM) for their roles in my scientific growth. The growth and discoveries obtained by the CCDM in the short time since its inception is astonishing. In particular, I would like to thank my close vi collaborators: Akila Thenuwara, Samantha Shumlas, Richard Remsing, Haowei Peng, Nuwan Attanayake, Yaroslav Aulin, Ravneet Bhullar, Ran Ding, and Loveyy Mohammad. I need to especially thank my lab members and peers, particularly Michael Gau who has been there step for step through this entire graduate school experience. Being stuck in the muck of the trenches is not all that bad if you have half of the fun we did. So the warmest thank you to all Zdilla lab members, past and present: Mike, Owen, Jeff, Sunny, Clif, Garvin, Sean, Shiva, Soumyajit, Birane, Carl, Taylor, Connor, Megan, Ravneet, Ran, Jake, Shu, and Kieara. I’d additionally like to thank the Strongin lab for accepting me as one of their own and teaching this organometallic chemist how to be a proper physical, materials chemist. Of course, I’d be remiss without acknowledging my family. A huge thank you is owed to my parents, Dennis and Karen McKendry. Not just for raising me right and providing what I need to reach my highest potential. The past five years have contained the highest and lowest moments of my life, and your love and support has been vital through all. Thanks to my siblings, Patrick and Megan. Whatever the distance, your ever present support is one of the pillars of comfort that ground me. Finally, thank you to Temple University and the Department of Energy for the funding and commitment to scientific research. Your trust in us with your resources is what drives science forward. Thank you for the opportunity to pursue knowledge. vii TABLE OF CONTENTS ABSTRACT………………………………………………………………………………iii ACKNOWLEDGEMENTS……………………………………………………………… vi LIST OF FIGURES……………………………………………………………………… xi LIST OF TABLES……………………………………………………………………… xiv CHAPTER 1: INTRODUCTION………………………………………………………. 1 1.1. Significance………………………………………………………………….. 2 1.2. Identifying catalytic candidates of interest…………………………………... 2 1.3. Birnessite…………………………………………………………………….. 4 1.4. Transition metal chalcogenides……………………………………………… 5 1.5. Summary……………………………………………………………………... 6 1.6. References cited……………………………………………………………… 8 CHAPTER 2: DECORATION OF BIRNESSITE WITH MN(III) LEADS TO 60- FOLD IMPROVEMENT IN WATER OXIDATION CATALYSIS……………….. 12 2.1. Introduction…………………………………………………………………... 13 2.2. Results and discussion………………………………………………………... 15 2.3. Conclusions…………………………………………………………………... 39 2.4. Experimental………………………………………………………………….. 40 viii 2.5 References cited……………………………………………………………….. 46 CHAPTER 3: THE ROLE OF DOPANT INCORPORATION IN BIRNESSITE: A STUDY OF COBALT DOPANT’S ROLE IN WATER OXIDATION ACTIVTY...48 3.1. Introduction…………………………………………………………………... 49 3.2. Results and discussion………………………………………………………... 52 3.2.1. Determination of candidates……………………………………… 52 3.2.2. Systematic doping of cobalt into the birnessite sheets for OER….. 56 3.3. Conclusions…………………………………………………………………... 72 3.4. Experimental………………………………………………………………….. 72 3.5 References cited……………………………………………………………….. 76 CHAPTER 4: INCORPORATION OF ACTIVE IRON SPECIES INTO THE COBALT-DOPED BIRNESSITE CATALYST: THE ROLE OF CONFINEMENT ON ACTIVITY………………………………………………………………………… 80 4.1. Introduction…………………………………………………………………... 81 4.2. Results and discussion……………………………………………………….. .84 4.3. Conclusions…………………………………………………………………. 107 4.4. Experimental………………………………………………………………... 107 ix 4.5 References cited……………………………………………………………... 109 CHAPTER 5: COBALT OXIDE SUPPORTED ON COBALT PERTELLURIDE YEILDS AND EFFECTIVE WATER OXIDATION CATALYST………………. 113 5.1. Introduction…………………………………………………………………. 114 5.2. Results and discussion………………………………………………………. 116 5.3. Conclusions…………………………………………………………………. 127 5.4. Experimental………………………………………………………………… 127 5.5 References cited……………………………………………………………... 131 x LIST OF FIGURES Figure 1.1: The OEC…………………………………………………………………….. 3 Figure 1.2: Structure of triclinic and hexagonal birnessite………………………………