Photocatalytic decompositions of methanol and ethanol on Au supported by pure or N-doped TiO2

•Au in nanosize markedly enhances the extent of photodecomposition of methanol.•The main products are methyl formate and H2.•At complete conversion the CO content is 3.9%, CO/H2 = 0.07.•Adding H2O to methanol decreased those values to 0.5% and to 0.07.

The effects of Au particles of different sizes were investigated on the photocatalytic decompositions of methanol and ethanol on pure or N-doped TiO2. IR studies revealed that the deposition of Au promoted the dissociation of both compounds during illumination and also resulted in the formation of formate species. Whereas the photo-induced decompositions of methanol and ethanol occurred to only a limited extent on pure TiO2, the deposition of Au, particularly as nanosized particles, markedly enhanced the rate and the extent of the photocatalyzed reactions. An interesting feature of the photodecomposition of methanol was that, besides H2, CO2 and CO, a significant amount of methyl formate was also produced. Addition of H2O or O2 to the alcohol in both cases decreased the level of CO formed, and in the case of methanol CO was completely eliminated. Au particles on N-doped TiO2 with a lower bandgap catalyzed the photodecompositions of both compounds even in visible light.

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