Theoretical Analysis of Transition-Metal Catalysts for Formic Acid Decomposition

Periodic density functional theory calculations are employed to determine the reaction energetics of formic acid decomposition on Ag, Cu, Pd, Pt, and Rh surfaces. We also extend the study to other transition-metal surfaces by scaling the adsorption energies of the reaction species with two independent descriptors: CO and OH adsorption energies. A microkinetic model is then developed to derive the kinetics of formic acid decomposition from the energy parameters. By incorporating the scaling relations in the microlcinetic model, the turnover frequencies for formic acid decomposition over the transition-metal surfaces are described as functions of the two descriptors. The variations in catalytic activity and selectivity from one metal surface to another, which are obtained from the first principles analysis, are in qualitative agreement with those obtained experimentally. The interpolation concept of adsorption energy is finally used to conveniently identify potentially interesting alloy catalysts for formic acid decomposition.