Optimizing dual-intermediates adsorption on Rh-based intermetallics for formic acid electrooxidation

Concurrently optimizing the pathway and electrocatalytic activity for formic acid oxidation reaction (FAOR) is significant but still challenging. Herein, surface and composition engineering strategies are integrated by constructing atomically ordered Rh0.9Pt0.1Fe ternary intermetallic (O-Rh0.9Pt0.1Fe). Supported by the in situ infrared spectra, the carbon monoxide (CO*) mediated indirect FAOR pathway on pure Rh is switched into a direct pathway on RhFe intermetallics (O-RhFe) with isolated Rh atoms, leading to a lower overpotential. Further composition engineering by forming O-Rh0.9Pt0.1Fe contributes to enhanced FAOR activity due to the stabilizing of COOH* intermediate, as indicated by the density functional theory calculations. Besides, O-Rh0.9Pt0.1Fe shows enhanced FAOR activity during potential cycling tests with fewer structural evolutions, while O-RhFe displays a decay. This study provides new insight into tuning reaction pathways and catalytic activity selectively via tailoring adsorption of different intermediates.