Adsorption of Formic Acid on Pd(111) Catalyst in the Gas Phase

It is important to understand the nature of formic acid (HCOOH) adsorption on transition metal surfaces so as to elucidate the mechanism of its decomposition in direct HCOOH fuel cells. Despite the overwhelming interest, not much is known about the adsorption behaviour of HCOOH on Pd(111) surfaces. This work presents a theoretical study of monomeric HCOOH adsorption on Pd(111) surfaces in the gas phase. The stable configurations of the adsorbed molecules on the surface are displayed, with some omitted in previous studies. Our calculations show that the most stable configuration is that with the hydroxyl O and H on C in HCOOH binding to the surface. The modes of adsorption of HCOOH dimer are presented on Pd(111) for the first time. It is found that both the monomer and dimer of HCOOH weakly interact with the surface. Our results are intended to provide valuable insights to understand the reactivity of HCOOH on Pd(111).