Unveiling the Impact of Anion-Tuning in Copper-Based Chalcogenides on the Oxygen Evolution Reaction

Transition metal chalcogenides have been found to be particularly effective in promoting electrochemical energy conversion due to their unique electronic structure that facilitates interfacial charge transfer through modulation of electron density around the catalytically active site. Transition metal chalcogenides are relatively inexpensive compared to precious metal based OER catalysts, which makes them attractive for large-scale applications. Moreover, metal chalcogenides exhibit excellent chemical stability, which is important for maintaining the activity of the electrode over time. This study delves into the impact of anion-tuning in metallic chalcogenides on their electrocatalytic efficacy for comprehensive water splitting. Specifically, copper-based chalcogenides (Cu 2 X, where X = O, S, Se, and Te) undergo systematic examination to investigate the influence of decreasing anion electronegativity and increasing covalency on electrocatalytic performance. Among the copper chalcogenides, Cu 2 Te has the highest oxygen evolution reaction (OER) activity and can sustain high current density of 10 and 50 mA cm −2 for 12 h. The difference in intrinsic catalytic activity of these chalcogenide surfaces have been also probed through density functional theory calculations, which was used to estimate energy of the catalyst activation step. It was observed that the hydroxyl adsorption on the surface catalytic site is critically important for the onset and progress of OER activity. Consequently, it was also noted that the –OH adsorption energy can be used as a simple but accurate descriptor to explain the catalytic efficiency through volcano-like correlation plot. Such observation will have a significant impact on developing design principle for optimal catalytic surface exhibiting high performance as well as prolonged stability. By understanding the impact of anion electronegativity on catalytic performance, we aim to unravel the underlying principles governing OER and contribute to the rational design of highly efficient catalyst surfaces.