d–p Orbital hybridization in RhSn catalyst boosts hydrogen oxidation reaction under alkaline electrolyte

Abstract

Exploiting a new strategy to design hydrogen oxidation reaction (HOR) catalysts with high performance under alkaline electrolyte is highly desirable for the development of alkaline exchange membrane fuel cells. Herein, we report the fabrication of a RhSn/C catalyst with strong d–p orbital hybridization through introducing p-block Sn metal to d-block Rh metal. The obtained RhSn/C catalyst exhibits remarkable HOR performance under alkaline electrolyte, with specific activity of 0.933 mA cm⁻², and excellent reversible CO tolerance. Experimental results and density functional theory calculations reveal that strong d–p orbital hybridization between Rh and Sn in RhSn/C leads to strengthened hydroxyl binding energy and reduced energy of potential-determining step, thereby boosting the HOR performance under alkaline electrolyte.