Atomically Dispersed Platinum on Gold Nano-Octahedra with High Catalytic Activity on Formic Acid Oxidation

Abstract

Platinum was epitaxially deposited on gold octahedral nanocrystals using an electrochemical method. The coverage of platinum on the gold surface was finely controlled from fully covered multiple overlayers (5 monolayers; denoted as ML) to atomically dispersed submonolayer (0.05 ML). Catalytic activity for formic acid oxidation increased significantly (0.52 A/mg(Pt) for 5 ML to 62.6 A/mg(Pt) for 0.05 ML) with decreasing coverage. This high activity resulted from the control of the reaction pathway toward direct oxidation producing no surface-poisoning species, induced by the absence of platinum ensembles and the bifunctional effect from neighboring Pt-Au sites. The distribution of atomically dispersed platinum was further confirmed by no activity for methanol oxidation, which necessitates platinum ensembles. This result exemplifies that a rational design of the catalyst nanostructure can lead to contrasting activities with the same catalyst, unprecedentedly high activity for formic acid oxidation vs no activity for methanol oxidation.