ABSTRACT
Heteroatom doping was recently regarded as an effective method to tune the band gap and improve the separation and transfer of photogenerated electron-hole pairs in semiconductor photocatalysts. Herein, a novel S,F-codoped Bi2WO6 (S,F-Bi2WO6) with suitable oxygen vacancies was synthesized via the hydrothermal-calcination and post-sulfurization, for efficient Cr(VI) reduction and methyl orange (MO) degradation under visible light. The amount of surface oxygen vacancies could be controlled by adjusting the S/F ratio during the doping process, which modulated the band structure and photogenerated charge behavior of Bi2WO6. The optimal S0.10F-Bi2WO6 exhibited an excellent photooxidation-reduction performance, which Cr(VI) reduction and MO degradation efficiencies were 1.6 and 2.6 times than those of the pristine Bi2WO6 without oxygen vacancy under visible-light, respectively. The enhanced photooxidation-reduction performance was because the right amount of oxygen vacancies could effectively narrow the bandgap and improve the separation efficiency of electron-hole pairs. Thus, this work offered a mild and simply approach for preparing heteroatom doped Bi2WO6 and a potential to be extended to the synthesis of other doped materials for environmental remediation.
ABSTRACT
A novel three-dimensional (3D) network rodlike Ag2S/Bi2SiO5 photocatalyst with a p-n heterostructure composed of ultrafine Ag2S nanoparticles (NPs) and Bi2SiO5 nanosheets was prepared using an anionic self-regulation strategy by a two-step hydrothermal process. The architecture facilitated the efficient transfer and separation of photogenerated electron-hole pairs. The optimal Ag2S/Bi2SiO5 composite (ABSO0.10) exhibited an excellent reduction activity (93.5% Cr(VI) removal in wastewater containing 50 mg·L-1 Cr(VI) within 90 min under visible light), which was about 11.2 and 25.6 times higher than that of the pristine Ag2S and virgin Bi2SiO5, respectively. Assisted by experiments and density functional theory (DFT) calculations, a possible photocatalytic mechanism for Cr(VI) reduction over the Ag2S/Bi2SiO5 composite under visible-light irradiation was proposed.
