Photocatalytic decomposition and oxidation of dimethyl ether over Au/TiO2

The photocatalytic vapor-phase decomposition and oxidation of dimethyl ether were investigated on pure and Au-promoted TiO2. Infrared spectroscopic studies revealed that dimethyl ether adsorbed on TiO2-based catalysts undergoes partial dissociation to methoxy. Illumination induced a surface reaction and led to the formation of formate species. Whereas pure TiO2 exhibited only a slight photoactivity, the deposition of Au on TiO2 significantly enhanced the extent of the photocatalytic decomposition to yield H2 and CO2 with a small amount of CO. Addition of H2O increased the extent of photocatalytic decomposition and eliminated the CO formed. A very high catalytic effect of Au/TiO2 was observed in the photocatalytic oxidation of dimethyl ether to produce H2 free of CO. When the bandgap of the TiO2 support was lowered by N-doping from 3.02 eV to 1.98 eV, the photocatalytic decomposition and oxidation of dimethyl ether were observed even in visible light.