What formate electro-oxidation can teach us about CO poisoning on Pt during biomass oxidation

Abstract

Catalyst deactivation by *CO poisoning remains a central challenge in the electrochemical oxidation of biomass-derived molecules such as glycerol and glucose. On platinum catalysts, *CO forms readily as a reaction intermediate, blocking active sites and requiring high overpotentials for removal—often leading to undesired overoxidation of valuable products. Understanding the fundamental origins of *CO formation is thus critical for designing more selective and stable catalysts. Here, we employ formate oxidation as a model system to study CO formation on Pt in alkaline media. Using operando surface-enhanced infrared absorption spectroscopy, we show that the adsorption configuration of formate governs whether CO poisoning occurs. Oxygen-bound formate (*OOCH) undergoes stable direct oxidation to CO₂, whereas carbon-bound formate-derived species, consistent with *COOH, disproportionate to form *CO–*OH and initiate surface poisoning. These findings provide a mechanistic framework for suppressing CO formation on Pt by selectively stabilizing oxygen-bound intermediates, with broader implications for improving the performance of biomass electrooxidation reactions.