The most widely studied photocatalysts have been based on modified TiO2, whether rutile or anatase, with bulk doping dominating modelling work in this topic. Such work has tended to focus on how doping modifies the energy gap of TiO2 and this is taken to signify improved efficiency. Such studies neglect entirely the fate of excited electrons and holes. Recently Di Valentin and others have modelled photoexcitation in TiO2 through a simple model in which a triplet state is imposed; this then promotes an electron to the conduction band and leaves behind a valence band hole. This model allows us to study electron and hole localisation and various energies associated with the photoexcitation process. In this contribution we describe our results of DFT simulations of electron and hole localisation in composite systems formed by modifying rutile and anatase TiO2 with different metal oxide nanoclusters. We find that the composite structure forces electrons and holes to separate which should reduce charge recombination. The patterns of electron and hole localisation depend on the identity of the oxide nanocluster modifier. Finally, the effect of photoexcitation on molecular adsorption of water and CO2 at these composites is investigated.

Characterising Electron and Hole Localisation on Surface Modified TiO2 Photocatalysts

253rd National Meeting (2017)

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