Hydrogen production from water–methanol solution over visible light active indium–titanium oxide photocatalysts modified with copper oxide

Titanium oxide coupled with different amount of indium oxides were studied for production of hydrogen under visible light irradiation from water–methanol solution. The photocatalysts were prepared by co-precipitation and characterized by surface area and pore analysis, X-ray diffraction, field emission scanning electron microscopy, UV–Vis diffuse reflectance spectra, and photoluminescence spectroscopy. With increases in indium oxide content, the surface area, visible light absorption and separation of photogenerated electron-holes were enhanced. For binary catalysts, the activity was highest for 16.7 at.% indium with hydrogen production of 1829 μmol/g/h. Incorporation of copper oxide further enhanced the activity with hydrogen production of 2149 μmol/g/h. The higher hydrogen production for ternary catalyst can be attributed to the synergistic effects of higher surface area, stronger absorption in visible light region and enhanced separation of photogenerated charge carriers. The hydrogen generation was attributed to partial oxidation of methanol to formaldehyde thereby producing pure hydrogen.