Density Functional Theory Study of Hydrogen and Oxygen Reactions on NiO(100) and Ce doped NiO(100)

Abstract The reaction mechanism of H2 and O2, as well as the electronic properties of NiO(100) and Ce-doped NiO(100), have been investigated using density functional theory (DFT) with the inclusion of on-site Coulomb corrections (DFT + U). Results indicate that the reactions of H2 and O2 occur favorably on the reduced surfaces of both NiO(100) and Ce-doped NiO(100). However, once the oxygen vacancy on the reduced surface is filled, the activation energy for H2 reacting with lattice oxygen increases on both surfaces, with Ce-doped NiO(100) showing a lower activation energy of 1.64 eV compared to 3.16 eV on pure NiO(100). Charge analysis clearly reveals that Ce doping brings excess electrons localized at O atoms, which significantly increases the lattice oxygen activity. These results are of great significance for understanding the role of Ce in the surface structure of NiO (100).