Physically and chemically synthesized TiO2 composite thin films for hydrogen production by photocatalytic water splitting

TiO2 thin films have been synthesized by radio-frequency magnetron sputtering and sol–gel method to study the hydrogen generation by photocatalytic water splitting under visible light irradiation. Photoelectrochemical cell with chemical bias, involving photo-anode in form of TiO2 film deposited on conducting indium tin oxide (ITO) film and Pt as cathode, is developed. The effect of conducting ITO layer on photo-voltage is studied by varying the thickness of ITO films. Constant H2 generation rate is obtained for long period of time by both the TiO2 films because of the separated evolution of H2 and O2 gas, thus eliminating the back-reaction effect. Sputter-deposited film as compared to sol–gel-synthesized film showed better H2 generation rate, mainly explained in terms of the higher visible light absorption achieved by oxygen vacancies created in the TiO2 film by the energetic target ions during deposition in pure Ar gas pressure.