Boosting charge separation of Sr2Ta2O7 by Cr doping for enhanced visible light-driven photocatalytic hydrogen generation

In the present study, we report a one-step hydrothermal synthesis of visible-light response Cr-doped Sr2Ta2O7 nanosheets for photocatalytic hydrogen generation. It is discovered that the Cr ion is successfully doped into the Sr2Ta2O7 nanosheet crystal lattice and uniformly distributed without changing the crystal structure and morphology of the Sr2Ta2O7 host. Compared to pristine Sr2Ta2O7, the as-prepared Cr-doped Sr2Ta2O7 photocatalysts show enhanced photocatalytic activity for hydrogen generation under visible-light irradiation. The spectroscopy and Mott–Schottky results reveal that proper Cr doping can narrow the band gap of Sr2Ta2O7 as well as facilitate the separation of photo-generated electrons and holes, thus enhancing the photocatalytic performance under visible-light irradiation. This work provides a simple approach to fabricate visible-light active tantalum-based oxide photocatalysts.