Highly Selective Photocatalytic Methane Oxidation to Methanol Using CO2 as a Soft Oxidant

Light-driven methane conversion to methanol with high selectivity is considered a challenging and promising reaction for sustainable development. Herein, Cu/CeO2 catalysts were prepared for photocatalytic methane conversion with CO2 as a soft oxidant. Methanol was the sole liquid product with a high selectivity of 96.2% and a high yield of 88.9 μmol g–1 h–1 for the 2Cu/CeO2 catalyst. Investigation of the structure–performance relationship indicated that oxygen vacancies facilitated the trapping of photogenerated electrons and avoided carrier recombination. In addition, as a soft oxidant, CO2 can also capture photogenerated electrons to be reduced to CO and further accelerate the formation of CH3OH. A catalytic mechanism study demonstrated that methane and hydroxyl were oxidized by photogenerated holes to •CH3 and •OH, respectively, and thus, methanol was generated through the combination of •CH3 and •OH.