Analysis of tin oxide supported transition metal single-atom catalysts for oxygen evolution reaction

Abstract

Water electrolysis using cost-effective electrocatalysts offers a promising avenue for cheaper green hydrogen production, efficient renewable energy storage, and widespread implementation. In recent years, single-atom catalysts (SACs) supported on acid-stable oxides have emerged as an important class of electrocatalysts due to their ability to maximize the efficiency of precious metal utilization and create well-defined single-site materials with unique electronic properties. Tin oxide (SnO₂) is a cheap, acid-stable oxide material with poor OER activity. In this work, we considered 29 SACs corresponding to 3d, 4d, and 5d transition metals with different configurations on SnO₂, including surface, subsurface, bulk SACs, and surface-adatoms, using spin-polarized density functional theory calculations for their OER activity and stability. We systematically evaluate the electronic structure trends, the adsorption energy of OER intermediates, OER catalytic activity using both AEM and LOM mechanisms, and the thermodynamic and aqueous stability of these SnO₂-supported transition metal SACs (TM-SACs). From a subset of stable TM-SACs, Rh and Pt SACs on the SnO₂ surface are identified as the most promising catalysts for experimental validation. Ir-SAC on SnO₂(110) also showed comparable activity to state-of-the-art IrO₂(110), suggesting significant cost reductions due to lower Ir-loading requirements. Based on these theoretical findings, rational catalyst design principles for next-generation oxide-supported TM-SACs for the OER are established.