Assembly of surface-defect single-crystalline strontium titanate nanocubes acting as molecular bricks onto...

Ti³⁺ self-doped single-crystalline SrTiO_3-x nanocubes acting as molecular bricks are successfully assembled onto Ti³⁺ self-doping single-crystalline TiO_2-x(B) nanorods through an effortless two-step hydrothermal process coupled with an in situ solid-state chemical reduction method. SrTiO_3-x nanocubes act as molecular bricks, which are uniformly assembled onto the surface of TiO_2-x(B) nanorods due to lattice matching. The band gap of the resultant SrTiO_3-x/TiO_2-x(B) sample is ∼2.97 eV, which exhibits excellent photocatalytic performance for the reduction of Cr(VI) and hydrogen production under visible light. The apparent rate constant k value for the photocatalytic reaction of SrTiO_3-x/TiO_2-x(B) for Cr(VI) reduction is ∼8 times higher than that of white TiO₂(B). The photocatalytic hydrogen production rate for SrTiO_3-x/TiO_2-x(B) is ∼160.2 μmol g^-1 h^-1, which is ∼5 times higher than that of white TiO₂(B). The enhanced photocatalytic activity can be considered to be caused by a synergetic effect of heterojunction formation and the introduction of Ti³⁺ self-doping, which can not only facilitate the separation of photogenerated charge carriers between TiO_2-x(B) and SrTiO_3-x, but also broaden the photoresponse from the UV to visible-light region.