Precious Metal-Free Catalysts Towards Efficient Oxygen Electrocatalysis

Abstract

Oxygen electrocatalysis, encompassing both the oxygen reduction reaction (ORR) and the oxygen evolution reaction (OER), is fundamental to the operation of fuel cells, metal-air batteries, and water electrolyzes. It is critical in the transition from conventional fossil fuel-based energy sources to clean energy alternatives. Typically, the catalysts employed in these processes have traditionally been based on precious metals like platinum and iridium. However, their scarcity and high cost pose considerable obstacles to the broad commercialization of such processes. To this end, developing cheap but efficient precious metal-free electrocatalysts is a much sought-after goal. Herein, in this Ph.D. research, various prospective precious metal-free (PMF) electrocatalysts are examined, combining experimental tools and density functional theory (DFT)-based first-principles computations, with a particular focus on validating the actual surface state under relevant electrochemical conditions. Firstly, Chapter 5 summarizes the DFT computed surface Pourbaix diagrams of 14 typical stable transition metal X-ides (e.g., oxides, nitrides, carbides, and hydroxides). It is found that each of these materials displays a distinct surface state from its original form when subjected to specified electrochemical conditions, which highlights the significance of the preliminary surface state verification. Chapter 6 reveals the activity origin of ZrN for ORR via a proposed analytical framework, which combines surface state verification, electric field effect computation, and micro-kinetic modeling. Chapter 7 reports an active perovskite and spinel oxides nanocomposite, SrCo0.4Fe0.6O3/CoFe2O4, for alkaline OER, which was synthesized by a feasible doping strategy. By integrating DFT calculations, especially the preliminary surface state analysis, the configuration and reaction mechanisms of this complex catalyst were elucidated. This thesis emphasizes the role of interdisciplinary approaches in modern electrocatalysis studies. It underscores the pressing need for sustainable solutions in the face of dwindling natural resources and environmental concerns.

Date of Award	25 Mar 2024
Original language	English
Awarding Institution	The University of Manchester
Supervisor	Carmine D'Agostino (Main Supervisor) & Stuart Holmes (Co Supervisor)