HCOOH decomposition on Pt(111): A DFT study

• Published in: Surface science 2016-06, Vol.648 (C), p.201-211
• Main Authors: Scaranto, Jessica, Mavrikakis, Manos
• Format: Article
• Language: English
• Subjects: Carbon dioxide; Carbon monoxide; Carboxyl; Cobalt; Decomposition; Dehydration; Dehydrogenation; Density functional theory; Formate; Formations; Formic acid; Pathways
• ISSN: 0039-6028; 1879-2758
• DOI: 10.1016/j.susc.2015.09.023

Formic acid (HCOOH) decomposition on transition metal surfaces is important for hydrogen production and for its electro-oxidation in direct HCOOH fuel cells. HCOOH can decompose through dehydrogenation leading to formation of CO2 and H2 or dehydration leading to CO and H2O; because CO can poison metal surfaces, dehydrogenation is typically the desirable decomposition path. Here we report a mechanistic analysis of HCOOH decomposition on Pt(111), obtained from a plane wave density functional theory (DFT-PW91) study. We analyzed the dehydrogenation mechanism by considering the two possible pathways involving the formate (HCOO) or the carboxyl (COOH) intermediate. We also considered several possible dehydration paths leading to CO formation. We studied HCOO and COOH decomposition both on the clean surface and in the presence of other relevant co-adsorbates. The results suggest that COOH formation is energetically more difficult than HCOO formation. In contrast, COOH dehydrogenation is easier than HCOO decomposition. We found that CO2 is the main product through both pathways and that CO is produced mainly through the dehydroxylation of the COOH intermediate. [Display omitted] •We investigated formic acid dehydrogenation through formate and carboxyl paths.•We analyzed carbon monoxide formation through different paths.•We provided an explanation for the experimental evidence of formate.•We found that carbon dioxide formation is easier than carbon monoxide formation.•We found carboxyl dissociation as the main path for carbon monoxide formation.