Constrasting photocatalytic activity of commercial TiO2 samples for hydrogen generation

Abstract

series of 20 commercial titanium dioxide samples, including Evonik P-25, Millenium, Huntsman,Crenox, Kronnos or Hombikat, have been tested as photocatalysts for hydrogen generation from wateror water/methanol mixtures under monochromatic visible light (532 nm) or polychromatic simulatedsun light irradiation. Remarkable variations in the photocatalytic activity were found from one sample toother. While the most active sample under monochromatic 532 nm irradiation was Millenium Tiona 595and the photocatalytic activity ranking follows the order of the red shift of the absorption band onset, theranking under simulated sun light was different and difficult to rationalize. Under simulated sun lightirradiation, the most active samples were Evonik P25 and Dupont Ti-pure. Overall, our study is of interestto illustrate the large variation in the photocatalytic activities for commercial TiO2samples dependingon the photocatalytic reaction and conditions used.