Electronic structure and water induced phase transformation in layered perovskite-like K2La2Ti3O10 photocatalyst for water splitting studied by DFT.

Layered perovskite-like oxide K 2 La 2 Ti 3 O 10 is a perspective photocatalyst for water decomposition at ultraviolet irradiation. In this paper using a density functional theory approach electronic structures of dehydrated and hydrated phases of K 2 La 2 Ti 3 O 10 have been studied. It has been found that the water induced phase transformation from I 4/ mmm to P 4/ mmm occurs in two steps: at first an increase in the distance between the perovskite layers prevails, and then a shift of the perovskite layers occurs with a moderate changing of the interlayer distance. The band structure calculations have done using the modified Becke-Johnson potential show that K 2 La 2 Ti 3 O 10 exhibits indirect band gap of about 3.1 eV. The valence band maximum potential is located at 2.23 eV (vs. normal hydrogen electrode), while the conduction band minimum potential is at −0.91 eV. This confirms the ability of K 2 La 2 Ti 3 O 10 both for photocatalytic oxidation of water (producing dioxygen and protons) or pollutants, and to reduce H+ to H 2. However, the transfer rate, estimated implicitly from the ratio of the effective masses of the photogenerated holes and electrons in valence and conduction bands, limits photocatalytic performance of K 2 La 2 Ti 3 O 10 due to separation ineffectiveness of charge carriers. • Both LDA and GGA fail to describe correctly band gap in K 2 La 2 Ti 3 O 10. • The mBJ potential gives an indirect band gap of about 3.1 eV in K 2 La 2 Ti 3 O 10. • Photocatalytic properties of K 2 La 2 Ti 3 O 10 for water splitting was studied. • Low transfer rate limits photocatalytic performance of pristine K 2 La 2 Ti 3 O 10. • Water induced phase transition in K 2 La 2 Ti 3 O 10 from I 4/ mmm to P 4/ mmm was modelled. [ABSTRACT FROM AUTHOR]