Tuning Energy Band and Local Crystal Structure of Photocatalysts By Doping

The energy band configuration is a critical factor that governs the photocatalytic activity of semiconductors. Elemental doping of semiconductors could introduce the local states in the mid-gap or shift the conduction band minimum and/or the valence band maximum. Therefore, doping can modulate the light absorption spectra and alter the photocatalytic activity. We have studied the effects of different doping strategies on the energy band configuration, the local crystal structure and the photocatalytic activity in different semiconductors such as TiO₂, AgTaO₃, Bi₂O₃ and La₂Ti₂O₇using the first-principle calculation. It has been found that isovalent mono-doping leads to slightly tuning of the energy band configuration and the local crystal structure. Aliovalent mono-doping usually induces the localized energy bands in the forbidden gap, which often reduces the photocatalytic activity. Compensated co-doping is an effective approach to improve the photocatalytic activity via narrowing the band gap without generating the localized energy band.

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