Understanding pH-Dependent Oxygen Reduction Reaction on Metal Alloy Catalysts

Exploring low-cost and high-efficiency catalysts for oxygen reduction reaction (ORR) kinetics in both acidic and alkaline environments could dramatically improve the efficiency of hydrogen fuel cells and their industrial applications. During the electrochemical process, the effect of pH is a complicating factor and is of great importance in identifying high-efficiency electrocatalysts. In this work, we conducted systematic computations to gain a deep understanding of the pH-dependent ORR activity on Pt, Pd, and their near-surface alloys (NSAs). The effects of pH were calculated by employing the double-reference method, and our calculated pH-dependent current densities are in good agreement with the experimental results. High-throughput calculations identified a series of NSA catalysts with superior ORR performance under acidic or alkaline conditions, and we have developed a pH-corrected theoretical model to efficiently estimate the ORR activity on metal catalysts. This work underscores the importance of considering pH effects when evaluating ORR activity from calculations and provides a strategy for designing superior ORR electrocatalysts in acidic and alkaline solutions.