Atomic and Molecular Adsorption on Cu(111)

Due to the wide use of copper-based catalysts in industrial chemical processes, fundamental understanding of the interactions between copper surfaces and various reaction intermediates is highly desired. Here, we performed periodic, self-consistent density functional theory (DFT-GGA) calculations to study the adsorption of five atomic species (H, C, N, O, and S), seven molecular species (NH3, CH4, N-2, CO, HCN, NO, and HCOOH), and 13 molecular fragments (CH, CH2, CH3, NH, NH2, OH, CN, COH, HCO, COOH, HCOO, NOH, and HNO) on the Cu(111) surface at a coverage of 0.25 monolayer. The preferred binding site, binding energy, and the corresponding surface deformation energy of each species were determined, as well as the estimated diffusion barrier and diffusion pathway. The binding strengths calculated using the PW91 functional decreased in the following order: CH > C > O > S > CN > NH > N > CH2 > OH > HCOO > COH > H > NH2 > NOH > COOH > HNO > HCO > CH3 > NO > CO > NH3 > HCOOH. No stable binding structures were observed for N-2, HCN, and CH4. The adsorbate-surface and intramolecular vibrational modes of all the adsorbates at their preferred binding sites were deternined. Using the calculated adsorption energetics, potential energy surfaces were constructed for the direct decomposition of CO, CO2, NO, N-2, NH3, and CH4 and the hydrogen-assisted decomposition of CO, CO2, and NO.