DFT+U Study on Catalysis by Co3O4: Influence of U Value and a Surface–Bulk Bi-U Strategy

The DFT+U method provides an effective approach to correctly reproduce the material bulk properties of strongly correlated transition metal oxides (TMO) such as magnetic ground states, electronic structure, and redox reaction energies. Therefore, the catalysis processes over these strongly correlated TMO surfaces are frequently simulated utilizing the DFT+U method with the U value fit by these reported bulk properties. However, it is generally acknowledged that the calculated results utilizing the DFT+U method depend on the applied effective U value. Due to the significantly different coordination environments, the fit U value based on the bulk properties might not be proper for the simulation of the catalysis process. Moreover, the possibly caused calculation errors still remain elusive. To clarify it, we systematically investigate the influence of the Hubbard U value on the molecule adsorption at different sites, CO oxidation, and first C–H activation of methane over Co3O4(110). It is found that with th...