Ta-substituted SnNb2−xTaxO6 photocatalysts for hydrogen evolution under visible light irradiation

Abstract

Ta-substituted SnNb_2−xTa_xO₆ was successfully prepared via a solid-state reaction to study the effect of Ta insertion in Nb sites on the crystal structure, photophysical properties, and photocatalytic activities for hydrogen evolution. Analyses of X-ray diffraction patterns and Raman spectra revealed that the substitution of Ta caused not only a more tightly packed atomic structure with greater crystal structural distortion, but also a shorter M–O bond length in MO₆ octahedra. Additionally, we observed a gradual increase in the band gap, changing the photoabsorption property and conduction band electronic structure. The SnNb_1.4Ta_0.6O₆ photocatalyst showed enhanced hydrogen evolution compared to pristine SnNb₂O₆. This result was mainly attributed to better transport ability of the photo-generated charge carriers.