Hydrogen production from renewables using photon energy to excite semiconductors is one of the most promising methods at present to replace fossil fuels-based processes.  This reaction requires in addition to a semiconductor with band gap energy within the solar radiation spectrum, the presence of an electron transport materials (such as noble metals) and in many cases a compound injecting electrons into the valence band to decrease the compeeting fast electron hole recombination process.  There are many approaches in designing active materials and systems for this reaction. Among them is the observed synergistic effect between two phases of the same semiconductor.  Many interpretations are given among them is the following. One phase such as the rutile phase of TiO2 with slightly lower band gap than the anatase phase, therefore with higher number of charge carriers, and the other one (the anatase phase) with slower electron-hole recombination rate.  In this work we address the possible role of this synergistic effect between two phases of TiO2 (anatase and rutile) as well as between (anatase and brookite) on hydrogen production.Another method relies on the use of alcohols as sacrificial agents for hydrogen production from water.  This reaction is however not well understood, in particular because methanol gives hydrogen too.  The extent of which hydrogen is made from water or from the alcohol is tested and analysed.

Hydrogen production from water over semiconductor materials: The role of synergism between different phases

244th National Meeting (2012)

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