Insights into the Effect of Pt Atomic Ensemble on HCOOH Oxidation over Pt-Decorated Au Bimetallic Catalyst To Maximize Pt Utilization

摘要

Density functional theory calculations have been employed to probe into a comparative study of HCOOH oxidation on Pt(111) and three PtAu(111) surfaces with different Pt atomic ensembles-decorated Au(111) surfaces, denoted as Pt ML, Pt6Au3, and Pt3Au6, respectively. Our results show that HCOOH dehydrogenation is dominant on PtAu(111) surface; as compared to Pt(111) surface, PtAu(111) surfaces are efficient for HCOOH dehydrogenation to CO2, and show an inhibiting effect to HCOOH dehydration to CO. The catalytic activity and selectivity of PtAu(111) surfaces toward HCOOH oxidation are obviously dependent on the Pt atomic ensemble of the reaction active center. The enhanced catalytic activity and selectivity of PtAu bimetallic catalysts toward HCOOH oxidation should be attributed to their suppression to the dehydration reactions of HCOOH, which is well confirmed by the reported experimental results that the high catalytic activity of PtAu catalyst is caused by the increased selectivity toward HCOOH dehydrogenation. It is found that Pt ML surface, consisting of 1.0 monolayer Pt on an Au substrate, is not only efficient in the utilization of Pt, but also highly active and selective toward the dehydrogenation of HCOOH oxidation, which can suppress the formation of poisonous species CO. In addition, the present results may be helpful for the search of prospective substitutes to Pt electrode for hydrogen production in the direct formic acid fuel cell.