Material Aspects of Hydrogen Production by Photocatalytic Water Splitting
M. Willert-Porada, S. Bouazza, D. Leykam, Z. Pajkic
University of Bayreuth, DE
Keywords: titaniumdioxide, electrophotocatalysis, photoconversionefficiency
Abstract:Photocatalytic water splitting is studied intensively because of the free availability of sunlight as energy source. A vast number of publications on semiconductive materials capable of water photolysis is available since 2000, which does not make the analysis of the real potential of this process easier. In the present paper the results of a comparative study on the photoconversion efficiency and total photocurrent of different nano-granualar and nano-tubular TiO2 coatings without any additional materials (metals, carbon, other dopants) are presented. The nano-granular coatings are made from commercial powders (P25) as well as non-commercial, with primary particle size of 5-10 nm and a bimodal pore size distribution . All samples have the same active area and are sintered on TCO-coated glass or generated by anodic oxidation on Ti. UV-light sources of different intensity but the same wave length as well as sources with different wavelengths and simulated sunlight were used. The ageing behaviour of the coatings was studied under variation of light intensity by 100x. Furthermore, by means of dimensionless number analysis the specific surface area of TiO2 with different morphology is compared, in order to elucidate the effect of powder morphology on the photocurrent density and photoconversion efficiency. The UV-VIS spectra of all materials are used for calculation of theoretical photoconversion efficiency.