Decomposition mechanism of HCOOH on Pt/WC(0001) surfaces: a density functional theory study

Abstract

ABSTRACT Study of formic acid (HCOOH) decomposition on tungsten carbide supported monolayer platinum surfaces (Pt/WC(0001)) is important for a better understanding of the development of direct HCOOH fuel cells (DFAFCs). In this study, periodic slab model and density functional theory (DFT) calculations were performed to investigate the gas phase dissociation pathways of HCOOH on Pt/WC(0001) surface. The results indicated that HCOOH, HCOO, COOH, HCO, H2O, CO, OH, and H were adsorbed on Pt/WC(0001) surface through chemisorption. Moreover, the minimum energy pathway for HCOOH into CO2 and CO was analysed in terms of the fracture of H–O, C–H, and C–O bonds. In the decomposition process of HCOOH, HCOO is the main decomposition intermediate of HCOOH, CO2 is the main decomposition intermediate of HCOO, and CO is the main decomposition product of cis-COOH, trans-COOH, and HCO. Furthermore, it was found that the most favourable route for HCOOH decomposition on the Pt/WC(0001) surface is HCOOH→HCOO→CO2, wherein CO2 formation from HCOO dehydrogenation is the rate determining step. WC as a carrier does not change the catalytic performance of Pt for HCOOH, but reduces the amount of Pt used, thus making Pt/WC(0001) a cost effective catalyst for DFAFCs.