Mechanistic Study of Pt-Catalyzed Electrooxidation of HCOOH in Acid Medium: Kinetic Considerations on the Effect of Solvation

Abstract

The HCOOH oxidation on Pt(111) under gas phase and the present simulated electrochemical environment have been studied systematically by combining density functional theory with mean-field kinetic analysis. Our present results indicate that HCOOH oxidation in acid aqueous-phase conditions is substantially different from that in gas phase. Using the present models, the detailed oxidation pathways are evaluated on Pt(111) under the effect of solvation. The present calculations show that HCOOH oxidation mainly proceeds via direct oxidation involving COOH intermediate, and HCOO is only a spectator in gas phase, whereas it mainly occurs via direct pathway including HCOO intermediate at the present simulated acid electrochemical interfaces and CO is a poisoning species that can block surface active sites, which can qualitatively and rationally explain some conflicting experimental and theoretical findings at present. Furthermore, the origin of solvation effect on HCOOH oxidation mechanisms is revealed. Our pres...