Quantum Mechanical Studies of Electrocatalysts for the Hydrogen and Oxygen Evolution Reactions

Abstract

One of the linchpins of a renewable energy future is energy storage. Despite rapid advancements being made in numerous areas, global energy storage capacity is currently only a small fraction of what is required. The enormity of the task ahead calls for new technologies to be researched and deployed at scale. One promising, nascent technology is water splitting. Progress in this area requires a deep understanding of the materials and processes involved. The work presented in this dissertation contributes to this undertaking using first-principles quantum mechanics calculations.

This dissertation presents research investigating properties of materials for catalyzing both the hydrogen evolution reaction (HER) and the oxygen evolution reaction (OER). In the first half of the dissertation, we study the behavior of a hybrid Pt-group metal/transition metal carbide (TMC) system, Pt/WC, and show that subtle similarities in its electronic structure to pure Pt explains the correspondence in activities observed experimentally. We then explore the correlation between various material properties and the experimental HER activity to identify a new descriptor that can be used to quickly and accurately screen new hybrid systems for their potential as HER catalysts. Finally, we incorporate this descriptor into a comprehensive methodology for identifying hybrid Pt-group/TMC catalysts for the HER.

In the second half of the dissertation, we study nickel oxyhydroxide (NiOOH) and related materials as OER catalysts. We study the structural and electronic properties of NiOOH and use these results to compare various oxygen evolution pathways on this material. We suggest that part of the reason for the ambiguity in experimental studies of this reaction is due to the simultaneous occurrence of several mechanisms. We then examine the effect of doping on NiOOH and show that there is a strong thermodynamic driving force for the incorporation of Fe and Co in the NiOOH lattice, which is consistent with experimental studies on incidental doping of NiOOH. Finally, we disqualify the possibility of enhancing the activity of the dominant exposed basal plane of β-NiOOH through substitutional doping.