Highly Selective Photocatalytic Aerobic Oxidation of Methane to Oxygenates with Water over W-doped TiO2

Graphical Not too radical : Low-cost and highly effective W-doped TiO 2 photocatalysts are prepared to achieve the photocatalytic oxidation of methane with O 2 under mild conditions. The increased separation of photogenerated carriers promotes the photocatalytic activity. The upshifted band structure prohibits the over-generation of hydroxyl radicals (⋅OH) to decrease the overoxidation of liquid oxygenates. Highly selective conversion of methane to oxygenates with O 2 as a green oxidant remains a great challenge. It is still difficult to suppress the generation of CO x ( x =1, 2) as undesired by-products due to unavoidable overoxidation reaction. Hence, tungsten-doped (W-doped) TiO 2 photocatalysts were designed with a tunable band structure for photocatalytic oxidation of methane to C 1 oxygenates using O 2 at low temperature (30 °C). The W-doping effectively modified the electronic and band structure of pristine TiO 2 to enhance photocatalytic performance. Liquid oxygenates productivity could reach as high as 12.2 mmol g −1 with high selectivity of 99.4 %. Moreover, CO x selectivity was effectively decreased from 21.2 % over TiO 2 to 0.6 % for W-doped catalyst. Detailed characterizations further disclosed that W-doping not only enhanced light absorption, but also promoted the separation of photo-generated carriers to improve methane conversion. This work provides new insights into the design of highly efficient photocatalysts for methane oxidation.