Construction of H4x K2x Sn2-x S4+x /TiO2 nanocomposites with enhanced visible light-driven photocatalytic performance

In this paper, a new photocatalyst with TiO2 nanospheres decorated on ultrathin layered thiostannate H4x K2x Sn2-x S4+x (X = 0.5-0.6, HKTS) nanosheets was successfully synthesized by a facile solvothermal method combined with the hydrolysis of tetrabutyl titanate and it was denoted as HKTS/TiO2. By adjusting the content of tetrabutyl titanate, composites with different Sn/Ti molar ratios were prepared. The composites were applied for RhB degradation under visible light irradiation, and the optimum proportion of HKTS/TiO2 was obtained. The results of X-ray diffraction, Raman spectroscopy, Fourier transform infrared spectroscopy and scanning electron microscopy confirmed that TiO2 was successfully decorated on HKTS nanosheets. The combination of TiO2 and HKTS extended the absorption wavelength of TiO2 from UV to visible light range, and the separation efficiency of photoexcited electron-hole pairs was also enhanced. The photocatalytic degradation rate of RhB over HKTS/TiO2-1.0 was almost 97.9% after 60 min illumination, which was higher than those of HKTS and pure TiO2. The photocatalyst exhibited excellent reusability and stability as the degradation rate of RhB was 95.7% even after three cycles. The photocatalytic mechanism experiment indicated that ·O2 - and h+ played a dominant role in the photocatalytic process. All these results indicate that the newly fabricated HKTS/TiO2 composites provide a high-performance photocatalyst for waste water treatment, and the application of thiostannate can be extended to the field of photocatalytic materials.