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Selective Photocatalytic Oxidation of Low Concentration Methane over Graphitic Carbon Nitride-Decorated Tungsten Bronze Cesium

Li, Yuan, Li, Jun, Zhang, Gaoke, Wang, Kai, Wu, Xiaoyong
ACS sustainable chemistry & engineering 2019 v.7 no.4 pp. 4382-4389
ambient temperature, carbon nitride, cesium, electrons, graphene, irradiation, methane, methanol, nanocomposites, oxidation, peroxidation, photocatalysis, photocatalysts, superoxide anion, tungsten, value added, value-added products
Although traditional thermal catalysis is usually used to convert methane into value-added products, its high reaction temperature results in a low performance–price ratio in conversion of low concentration methane. In this regard, we synthesized a series of mace-like g-C₃N₄-decorated Cs₀.₃₃WO₃ nanocomposites for photocatalytic conversion of low concentration methane under mild conditions. The optimized g-C₃N₄@Cs₀.₃₃WO₃ (weight ratio = 3:7) photocatalyst selectively converted low concentration methane (1000 ppm) into methanol with a yield of 4.38 μmol/h/g under light irradiation and at room temperature. Both performance experiments and trapping experiments verified that methane activation and methyl oxidation were involved in the photocatalytic conversion process of methane. The •O₂– first activated the methane to methyl on the surface of g-C₃N₄ in the composite and then the photogenerated electrons from the Cs₀.₃₃WO₃ in the composite inhibited the peroxidation and increased the generation of methanol. This research provides a new route to design and synthesize photocatalysts for converting methane into value-added chemicals.