Platinum-group metals (PGMs) are among the most active electrocatalysts for the ethanol oxidation reaction. Nevertheless, their intrinsic efficacy in C–C bond scission remains contentious, and unequivocal molecular-level evidence is still wanting. To approach it, we employed in situ electrochemical attenuated total-reflection surface-enhanced infrared spectroscopy under both conventional and thin-layer flow cells as the main method, for the first time, by using the relative population ratio of COad (η) as the descriptor on the identical electrode, to rank the C–C bond cleavage activity of the four PGMs as Ir > Rh > Pd > Pt in alkaline media from both thermodynamic and kinetic perspectives. Moreover, the maximized C–C bond cleavage activity was found at 0.20 ∼ 0.30 V for Pt, Rh, and Ir and at 0.40 ∼ 0.50 V for Pd. This work develops a molecular-level strategy for probing catalytic processes through a simple descriptor and might offer a fresh perspective for investigating surface reaction pathways.
Wei et al. (Thu,) studied this question.