Optical and photocatalytic properties of S doped BiOCl nanosheets with tunable exposed {0 0 1} facets and band gap

Element doping and crystal facet engineering are considered effective methods to improve the optical and photochemical properties of semiconductor materials. In this study, we successfully produced S-doped BiOCl nanosheets with a controllable band gap and exposure ratio of {0 0 1} facets via a facial hydrothermal reaction wherein thioacetamide served as an S donor and played a vital role in regulating the growth of the (0 0 1) plane of BiOCl. The PL and UV results suggested that S-doped BiOCl nanosheets with dominant {0 0 1} facets possessed photo-induced carriers with longer lifespans and enhanced absorption of visible light compared to undoped BiOCl. The photocatalytic results showed that S-doped BiOCl with a Bi/S molar ratio of 100:3 exhibited the highest photodegradation efficiency, which was 2.6 times that of the undoped BiOCl nanosheets. The improved photocatalytic efficiency could be explained by the synergistic effect of the enhanced exposure ratio of the {0 0 1} facets and the reduced bandgap, leading to broadened light absorption and enhanced separation of photoexcited carriers. The possible mechanism of the separation and transfer of electron-hole pairs was analyzed and discussed. This work provides useful information for the synthesis of efficient semiconductor photocatalysts, combining the merits of non-metal doping and crystal engineering.