Flux synthesis of Bi2MO4Cl (M = Gd and Nd) nanosheets for high-efficiency photocatalytic oxygen evolution under visible light

摘要

The Bi2MO4Cl (M = Gd and Nd) nanosheets were prepared by a molten salt flux method for the first time. The resulted Bi2GdO4Cl (F-BG) nanosheets showed the highest photocatalytic activity for oxygen (O-2) evolution and trypan blue (TB) degradation than Bi2NdO4Cl (F-BN), Bi2GdO4Cl (S-BG) and Bi2NdO4Cl (S-BN) synthesized by a solid-state method. The F-BG nanosheets showed the larger specific surface areas and abundant pores, which could provide more reactive sites. The photoelectrochemical and photoluminescence (PL) results revealed that F-BG sample had the excellent separation and transfer rates of photogenerated charge carriers, leading to the highly photocatalytic performance for both O-2 evolution and TB degradation. The UV-Vis diffuse reflectance spectra (DRS) showed all samples had the visible-light-responsive characteristic. The radical trapping experiment revealed hole (h(+)) played a major role, while superoxide radical (center dot O-2(-)) contributed a little to photocatalytic degradation process. Thus, a possible photocatalytic mechanism was proposed based on the radical trapping experiment. This work shows us a useful insight into the preparation of highly active bismuth-based oxyhalide nanosheets photocatalysts by a molten salt synthesis through surface modification and morphology control and provides the possibility of water splitting under visible light.