Adsorption, dissociation, and hydrogenation of CO ₂ on WC(0001) and WC-Co alloy surfaces investigated with theoretical calculations

We applied periodic density functional theory to investigate the adsorption of CO ₂ on WC(0001) and various WC-Co alloy surfaces and discuss the reaction trend of dissociation of CO ₂ and hydrogenation on these surfaces. We employed an electron localization function (ELF) to investigate the effect of electron localization or delocalization on various WC-Co alloy surfaces with a varied Co coverage; the partial-delocalization surfaces (WC-Co (0.25 ML) surface) exhibit the largest energy of adsorption of CO ₂ (-1.61 eV) on all calculated surfaces. When we increased the Co ratio to form a WC-2Co (0.50 ML) surface, the activation energy for the dissociation CO ₂→CO+O decreased to 0.57 eV. The energy of CO ₂ hydrogenation to form formate (CO ₂+H → HCOO) decreases with Co coverage due to increased electron delocalization.