Perovskite-like Oxide KCuTa3O9 Decorated with Ultra-Thin Carbon Layers as a Visible-Light-Response Photocatalyst for Hydrogen Evolution

Development of a perovskite-like metal oxide (PLMO) photocatalyst with a visible light response has long been pursued in the field of photocatalysis. Herein, a PLMO KCuTa3O9 (KCTO) photocatalyst with a narrow band gap of 2.68 eV and a suitable energetic position that straddles the water redox potential has been developed. Subsequently, a 3 nm-thick carbon layer was coated uniformly on the surface of KCuTa3O9 (KCTO@C). The optimized KCTO@C-10 photocatalyst exhibits an excellent photocatalytic hydrogen evolution rate under visible light irradiation (lambda > 420 nm), which is 2.87 times higher than that of pure KCTO. Systematic investigations reveal that carbon layer coating on the surface of KCTO not only expands visible light absorption but also promotes electron transfer, facilitating photoinduced electron-hole separation. In addition, an unobvious structural change of the KCTO@C-10 photocatalyst after four cycle tests demonstrates its good photochemical stability. This work offers a perspective for exploiting carbon-coated perovskite-like metal oxide photocatalysts to achieve high-efficiency photocatalytic hydrogen evolution.