Photocatalytic Production of Hydrogen from Water over Pt/N-Doped Titania under Visible Light Irradiation
Photocatalytic water splitting is a very promising technique for hydrogen production since water and solar light are abundant and renewable resources. TiO2 is the most preferable semiconductor photocatalyst for photocatalytic processes due to its high photosensitivity, high stability, and non-toxic nature. Despite the positive attributes of TiO2, there are a few drawbacks associated with its use: (i) charge carrier recombination occurs easily and (ii) the band gap absorption does not allow the utilization of visible light. In order to solve the recombination problem, the addition of a noble metal as a hole scavenger is needed. To improve visible light absorption ability of TiO2, anion doping, such as nitrogen-doped TiO2, is effective method to enhance visible light response. In this study, N-doped mesoporous TiO2 and N-doped non-mesoporous commercial TiO2, Degussa P-25, prepared at different N-doping contents and calcination temperatures were investigated. The results of UV-Vis spectra showed that absorption edges of both N-doped mesoporous TiO2 and N-doped P-25 were extended into the visible light range. N-doped mesoporous TiO2 prepared at a urea: TiO2 molar ratio of 1:1 and a calcination temperature of 2500C exhibited the highest efficiency for photocatalytic H2 evolution. The photocatalytic activity of the N-doped mesoporous TiO2 was improved in the present of Pt via incipient wetness impregnation method. The results indicated that the optimum Pt loading content was found to be 1.6 wt%.