Transition Metal Single-Atoms on V3C2O2 MXene Nanosheets for Efficient Methane-to-Methanol Conversion: First-Principles Investigation

At present, it is still challenging to achieve efficient electrocatalytic methane conversion to methanol. In this work, we have designed 14 different transition metal single-atoms on V3C2O2 MXene nanosheets (V3C2O2-M) as single-atom catalysts (SACs) for electrochemical methane oxidation. The density-functional theory calculations confirm the stability of V3C2O2-M, M = 3d: Fe, Co, Cu, 4d: Mo, Ru, Rh, Pd, 5d: W, Ir, and Pt. The activation energy of the CH3-H bond is found to show a linear dependence on the proton affinity of the reactive oxygen on V3C2O2-M. Especially, V3C2O2-Ru exhibits an ultralow energy barrier (0.04 eV) for the H3C-H activation due to the strong proton affinity of the reactive oxygen, caused by an upward shift of the p-band center. Furthermore, V3C2O2-Ru can achieve 100% methanol selectivity by controlling the external potential between 1.40 and 1.90 V during methane conversion. These results show that Ru SACs on V3C2O2 MXene nanosheets have great potential for electrochemical methane conversion to methanol.