An Unusual Exchange Mechanism in the Tafel Reaction on Pt(110)‐(1×1) Surfaces

• Published in: ChemElectroChem Vol. 6; no. 13; pp. 3279 - 3284
• Main Authors: He, Zheng‐Da, Chen, Yan‐Xia, Juarez, Fernanda, Santos, Elizabeth, Schmickler, Wolfgang
• Format: Journal Article
• Language: English
• Published: Weinheim John Wiley & Sons, Inc 01.07.2019
• Subjects: Computer simulation; Density functional theory; Exchanging; Hydrogen atoms; Hydrogen evolution; platinum single crystals; Reaction kinetics; reaction paths; Tafel reaction
• ISSN: 2196-0216; 2196-0216
• DOI: 10.1002/celc.201900681

Experiments suggest that on Pt(110) the Tafel reaction is the rate determining step in hydrogen evolution. We investigate the kinetics of this step on the unreconstructed surface by a combination of density functional theory and grand‐canonical Monte Carlo simulations. We identify two favorable reaction paths: The recombination of a hydrogen atom adsorbed on a bridge site with one adsorbed on top, and an exchange mechanism involving two hydrogen atoms adsorbed on top and one adsorbed on a bridge site. The latter results in a transfer coefficient of two in agreement with experiment, and seems to be the dominant step. A concerted effort: Platinum is the best catalyst for hydrogen evolution, and Pt(110) is the most active principal plane. A combination of DFT and Monte Carlo simulations suggests that the rate‐determining step involves three adsorbed hydrogen atoms: Two neighboring atoms which combine and a third atom which replaces an atom that has left.