Theoretical Analysis of Transition-Metal Catalysts for Formic Acid Decomposition

Periodic density functional theory calculationsare employed to determine the reaction energetics of formicacid decomposition on Ag, Cu, Pd, Pt, and Rh surfaces. Wealso extend the study to other transition-metal surfaces byscaling the adsorption energies of the reaction species with twoindependent descriptors: CO and OH adsorption energies. Amicrokinetic model is then developed to derive the kinetics offormic acid decomposition from the energy parameters. Byincorporating the scaling relations in the microkinetic model,the turnover frequencies for formic acid decomposition overthe transition-metal surfaces are described as functions of thetwo 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.KEYWORDS: formic acid decomposition, hydrogen storage, hydrogen production, catalyst, density functional theory, scaling relation, microkinetic model, first principles analysis, descriptor based analysis, interpolation