Designing the Interface of Transition Metal Phosphides for Electrocatalysis

Abstract

Colloidally synthesized nanocrystals are a compelling class of materials for catalysis due to their high surface-area-to-volume ratios. The surface chemistry of nanocrystal catalysts is particularly important because of its impact on the electronic structure of the nanocrystal but also because it comprises the interface between the catalyst, substrate, solvent, and even electrolyte in the case of electrocatalysis. This dissertation focuses on how the interface between a nanocrystal catalyst and the substrate can be designed and modified to promote electrocatalytic activity. Chapter 1 highlights the important role interfaces play in energy conversion and storage technologies and introduces key electrochemistry concepts for the remainder of the thesis. Chapter 2 describes how common surfactants impact the electrocatalytic activity of cobalt phosphide (CoP) nanocrystals for the hydrogen evolution reaction (HER) in aqueous electrolyte solutions. Chapter 3 discusses the unintuitive differences in electrochemical behavior between nanocrystal catalyst films in aqueous versus non-aqueous solvents and examines the important role outer-sphere solvent interactions play in electrocatalytic activity of transition metal phosphides for HER.