Theoretical investigations of HCOOH decomposition on ordered Cu-Pd alloy surfaces

Abstract

Formic acid (HCOOH) decomposition is studied on four ordered Cu-Pd compounds (B2-type CuPd, L10-type CuPd, L12-type Cu3Pd, and L12-type CuPd3) through systematic density functional calculations. The crystal structures and atomic compositions play a significant role to control activity and selectivity of catalysts. The OH bond dissociation barrier of HCOOH is less than that of the CH bond scission, and the most high selectivity for OH/CH dissociation is found on the single Pd atom alloyed in Cu lattice of L12 Cu3Pd(111) surface. However, the contiguous Pd atoms greatly facilitate hydrogen production from HCOOH, and the barriers are 0.44 and 0.73 eV for the dehydrogenation reactions on of HCOOH → HCOO + H → CO2 + 2H on L10 CuPd(111) surface. Though the CO formation pathway is energetically favorable for COOH decomposition on the ordered Cu-Pd surfaces except Pd-rich ordered CuPd3(111) surface, the adsorbed CO can be easily removed due to the weaker interaction compared with pure Pd surfaces. The calculated results indicate that L10 CuPd and L12 CuPd3 alloys are effective catalysts for formic acid decomposition with high catalytic selectivity and activity.