Synthesis and photocatalytic activity of Cu2O hollow nanospheres/TiO2 nanosheets by an in-situ water-bath method

•Hollow double-shell Cu2O is evenly loaded on TiO2 nanosheets by a simple in-situ water-bath method.•The plausible formation process of Cu2O/TiO2 nanocomposite is revealed.•Cu2O/TiO2 exhibits a 6.3 times higher photoactivity than TiO2 for the degradation of methyl orange. Hollow double-shell Cu2O are evenly loaded on TiO2 nanosheets by a simple in-situ water-bath method, which exhibits a photoactivity 6.3 times higher than TiO2 nanosheets. This in-situ water-bath method is simple, mild and general, which could be extended to the other novel composites materials. [Display omitted] In this work, a simple in-situ water-bath method is used to load Cu2O hollow nanospheres (named as H-Cu2O) on TiO2 nanosheets (named as TiO2-NS). H-Cu2O of 160–250 nm in diameter is uniformly supported on the surface of TiO2-NS. H-Cu2O has a novel hollow core-shell structure with a double shell. Specifically, the diameters of inner hollow spheres are 80–90 nm and the thickness of the outer shell and inner shell are about 40 nm and 25 nm, respectively. It is conjectured that the outer and inner shells of H-Cu2O can both provide adsorption and reaction sites, favoring the photocatalytic reaction. The UV–visible diffused reflectance spectra show that compared with TiO2-NS, the H-Cu2O/TiO2-2 sample with adding 80 mg of TiO2-NS shows a stronger visible light absorption. Furthermore, the steady-state photoluminescence (PL) and photocurrent spectra show that H-Cu2O/TiO2-2 has a weaker PL intensity at about 370 nm and 6 times higher photocurrent intensity than TiO2-NS, demonstrating that H-Cu2O/TiO2-2 has higher charge separation efficiency. Compared with TiO2-NS, the photocatalytic activity of H-Cu2O/TiO2-2 under UV light (λ ≤ 400 nm) increase by 6.3 times for the degradation of methyl orange. The improved photocatalytic activity can be attributed to the enlarged BET areas (6.1 m2 g-1/H-Cu2O/TiO2-2 vs. 3.8 m2 g-1/TiO2-NS), the enhanced light adsorption, and the improved charge separation efficiency. The reported in-situ water-bath method is simple, mild, and general, which could be extended to other novel composite materials.