Processus clés de la photocatalyse à base de TiO2 : (1) génération de paires electron-trou e-/h+ par excitation par la lumière, (2) et (3) réactivités en surface gouvernées par les électrons et les trous.
Interface modèle dans un photocatalyseur graphène/TiO2 anatase (101) déficient en oxygène.
Photocatalysis uses solar energy to carry out energetic and chemical processes. It is a potentially environmentally-friendly technology with varied applications in the fields of solar cells, water splitting, degradation of environmental pollutants or water and air purification. In heterogeneous photocatalysis, semiconductors such as TiO2 are commonly used as photocatalysts. After light absorption, electron transfer between the valence and conduction bands generates electron-hole pairs, enabling electron- and hole-governed reactivities on the oxide surface. With weak absorption of light in the visible range, however, stoichiometric TiO2 alone does not allow commercialization of photocatalysts active in the visible range without modification of its electronic structure by introduction of point defects or dopants, or by sensitization using graphene derivatives, for example.
We use density functional theory (DFT) to establish electronic structure calculation protocols in localized bases, to propose TiO2-based photocatalysts with response in the visible range. To this end, periodic hybrid DFT calculations are combined with electrostatic embedding techniques on non-periodic models to characterize the structural, electronic and photophysical properties of composite photocatalysts and their constituents. This project is supported by GENCI with an allocation of 1.25 Mh on the Joliot-Curie supercomputer.