Unraveling the Origin of Nb-Doped Pt Nanoparticle Electrocatalysts for the Methanol Oxidation Reaction.

Owing to the high activity of Nb in CO oxidation, Nb-modified Pt electrocatalysts have recently attracted considerable attention in the methanol oxidation reaction (MOR). However, the mechanism by which Nb mitigates CO poisoning and the key intermediate species involved in the MOR process on Nb-Pt catalysts are poorly understood. Here, we elucidate the origin of CO poisoning resistance and the improvement of electrocatalytic properties of Nb-doped Pt nanoparticles. The catalyst demonstrates a 7.2-fold mass activity for MOR and a 157 mV lower onset potential for CO oxidation compared to commercial Pt/C. In situ attenuated total reflection surface-enhanced infrared absorption spectroscopy and computational results reveal that Nb doping not only weakens the CO adsorption energy but also enriches local OH coverage, while resulting in the bridge adsorption of critical intermediates. This work provides mechanistic insights into the role of Nb in improving CO tolerance and catalytic performance of Nb-modified Pt nanostructures toward MOR.