Hybrid functional study on optical properties of Sr2M2O7−xNx(M = Nb, Ta) photocatalysts with perovskite-slab structures

Abstract

Abstracts We present the electronic, dielectric, and optical properties of layered perovskite pure and N-doped Sr 2 M 2 O 7 (M = Nb and Ta) based on density functional theory with the HSE06 approximation. The band gaps for pure Sr 2 M 2 O 7 (M = Nb and Ta) are consistent with the experimental data. Optical properties are obtained and compared with the experimental results. Pure Sr 2 Nb 2 O 7 and Sr 2 Ta 2 O 7 have broad applications in photocatalysis in the ultra-violet region. In contrast with Sr 2 Ta 2 O 7 , the absorption ability of Sr 2 Nb 2 O 7 is slightly stronger. The N doping in Sr 2 Nb 2 O 7 shifts the light absorption boundary into the visible region. The optical absorption effect of Sr 2 Nb 2 O 5 N 2 is better than Sr 2 Nb 2 O 6.5 N 0.5 in the visible region. The N doping in Sr 2 Ta 2 O 7 reduces the band gap and produces visible light absorptions. Sr 2 Ta 2 O 5 N 2 shows higher absorption effect in the visible light region than Sr 2 Ta 2 O 6.5 N 0.5 .