Unravelling the bi-functional role of cation-regulated surface hydroxyl kinetics in Pt-catalyzed alcohol fuel cells

Electrocatalytic alcohol oxidation is pivotal for renewable energy conversion, yet its widespread application is hindered by generally low efficiency, necessitating the development of advanced catalytic systems with boosted electro-oxidation kinetics. In an alkaline electrolyte, the effect of alkali metal cations has been identified as a key impacting factor on the alcohol oxidation activity, but the underlying mechanistic interactions remains insufficiently explored. Here we elucidate the fundamental cation effects on hydroxyl (OH ads ) adsorption and subsequent surface bi-molecular kinetics in Pt (and alloys)-catalyzed alcohol electro-oxidations through combined electrochemical voltammetry, in situ surface enhanced infrared absorption spectroscopy (SEIRAS) and in situ electrical transport spectroscopy (ETS). Systematic evaluations reveal that alkali metal cations regulate the micro-electro-kinetics by modulating the surface coverage of OH ads , which acts bi-functionally as both reactant species and spectator in alcohol oxidations. A matching adsorption kinetics of OH ads and alcohol is key towards the optimal alcohol oxidation activity, providing valuable insights into the cation-mediated alloy catalyst systems and high-concentration conditions in alcohol fuel cells.