Impact of non-metal dopants on band-gap engineering and photocatalytic ability of λ-Ta^sub 2^O^sub 5^ from a hybrid density functional study

The large intrinsic band gap in Ta2O5 photocatalyst has essentially hindered its potential applications in visible light irradiation. Doping non-metal elements into semiconductors is found to be an effective strategy for narrowing the band gap. In this study, we investigated the influence of non-metal atoms X (X=C, N, F, Si, P, S, Cl, Se, Br, and I) on the band gap and photocatalytic ability of λ-Ta2O5 by means of first-principles calculations. As to the reported N-doped and S-doped Ta2O5, our calculations well explained experimental observations on the band gap narrowing and photocatalytic redox capability. Based on the computed formation energies, we found that the preferred doping site of a non-metal atom is mostly related to the size and common valence of dopant. Our results predict that C-, P-, Si- and Se-doped Ta2O5 are promising visible-light-responsive photocatalysts. The former two systems can be used in photocatalytic decompositions of organics, and the latter two systems may be applied to overall water splitting reactions. Further experimental studies are highly demanded to explore the promising applications of these four systems in the photocatalytic field.