Differential Reactivity at Edge and Terrace Sites of Transition Metal Dichalcogenides

• Main Author: Wiensch, Joshua David
• Format: Others
• Published: 2017
• Online Access: https://thesis.library.caltech.edu/10145/7/Thesis-Final-2017-Joshua-David-Wiensch.pdf; Wiensch, Joshua David (2017) Differential Reactivity at Edge and Terrace Sites of Transition Metal Dichalcogenides. Dissertation (Ph.D.), California Institute of Technology. doi:10.7907/Z9GB223X. https://resolver.caltech.edu/CaltechTHESIS:04232017-102424232 <https://resolver.caltech.edu/CaltechTHESIS:04232017-102424232>

<p>This dissertation describes efforts towards understanding the surface reactivity and catalytic properties of a promising class of materials, which have the potential to be integrated as part of a solar-fuels device and help usher-in the solar age. Because of their multifunctional behavior, layered transition metal dichalcogenides are potential candidates for not only light absorption in a solar fuels device, but also as catalysts for the hydrogen evolution reaction.</p> <p>We begin in chapter one with an introduction related to global energy sources and trends, highlighting the motivation for the work performed in this dissertation. The second chapter describes a discovery into the interplay of pH and morphology for the hydrogen evolution reaction on MoSe2. This discovery suggested a possibility for a different mechanism for the hydrogen evolution reaction being active in acidic and alkaline media. The third chapter describes an exploration into selective small molecule binding to macroscopic edge sites of MoSe2 and WSe2. The fourth chapter is a study of the protective effects of ALD-TiO2 when grown on a variety of MX2’s. The inert nature of terrace sites in MoSe2 and other MX2’s prevented the growth of a conformal thin film of TiO2 but yielded nanoparticles on the surface instead. Finally, in appendix A, I describe the work performed prior to joining the Lewis group relating to the design and synthesis of a binuclear titanium complex that was explored for its ability to copolymerize olefins and enable the incorporation of polar monomers.</p>