Using Al2O3 defect levels to enhance the photoelectrocatalytic activity of SnS2 nanosheets

Hexagonal SnS2 nanosheets and Al2O3/SnS2 composites were fabricated via a one-step hydrothermal synthesis method. The investigation indicates that hexagonal SnS2 with diameters of 100-200 nm are well dispersed on the surface of Al2O3. The band gap of SnS2 after coupling with 11 wt%-Al2O3 is reduced by 0.042 eV compared with the pure SnS2. The composite with 11 wt%-Al2O3 shows the highest photocurrent density of 37 μA/cm2 at 0.49 V (vs. Ag/AgCl) under visible light (λ>420 nm), which is approximately 1.2 times that of the pure SnS2 nanosheets. Photoelectrocatalytic measurements demonstrate that an appropriate amount of Al2O3 can enhance the photoelectrocatalytic efficiency of SnS2. The 11 wt%-Al2O3/SnS2 composite (AOSS-11) can degrade 85.9% MB after 3 h under visible light illumination at an applied potential of 0.49 V (vs. Ag/AgCl). The highly effective photoelectrocatalytic activity of the Al2O3/SnS2 composite is attributed to the efficient separation of photoinduced electron-hole pairs based on the defect levels. This work may provide a new design idea for constructing the effective SnS2-based photocatalysts with other defective semiconductors.