Adsorption and dissociation reaction of carbon dioxide on Ni(1 1 1) surface: molecular orbital study

Calculations based on the atom-superposition and electron-delocalization molecular orbital (ASED-MO) method show that at low coverage, CO2 binds on the di-σ(1), Δ, μ, and π/μ sites in the bent configuration of lying-down, and on the 1-fold, 2-fold, and 3-fold sites in the perpendicular configuration. The surface adsorbed binding site of carbon dioxide is strongest at the di-σ(1) site and weakest at π/μ site. Chemisorbed CO2 bends because of metal mixing with 2πμ→6a1 CO2 orbital. The dissociation reaction occurred in two steps, with an intermediate complex composed of atomic oxygen and π-bonded CO. The OCO(1) angle of reaction intermediate complex structure for the dissociation reaction is 100° on the Ni(1 1 1) surface. The activation energy was 1.27 eV.