论文部分内容阅读
The hybridization between the outmost s orbitals of metal (Bi3+,Sn2+,Pb2+,Ag+) and O 2p orbitals has been widely employed to develop innovative semiconductors with upshift valence band as well as extended visible light response,but it is still challenging to obtain photocatalyst with absorption edge of above 550 nm.Here we report a novel Sn2+-based oxyfluoride Sn2TiNbO6F (STNOF) photocatalyst with a pyrochlore structure to exhibit an extended absorption edge to 650 nm and dual functionalities of both water reduction and oxidation.Density functional theory calculations suggest that the unprecedented broad-spectrum response of STNOF is mainly ascribed to the strengthened hybridization between O 2p and Sn 5s orbitals remarkably upshifting the valence band,which is caused by the distortion and com-pressive strain in the SnO6F2 dodecahedron with second-order Jahn-Teller effect due to partial fluorine substitution.The structural distortion and compressive strain are experimentally confirmed by the Fourier-transformed extended X-ray absorption fine spectra.As probe tests of the photocatalytic func-tionalities,water reduction and oxidation half reactions were examined to see obvious H2 and O2 evolu-tion under visible light irradiation.This work may provide an alternative strategy of developing extended visible light responsive semiconductors for promising solar energy conversion.