Novel phosphorus-doped Bi2WO6 monolayer with oxygen vacancies for superior photocatalytic water detoxication and nitrogen fixation performance

Abstract

Chemical phosphorus doping has recently regarded as an effective method for band gap and charge transfer kinetics regulation of semiconductor photocatalysts. However, few more P-doped photocatalysts are investigated except TiO2 and g-C3N4 systems up to now. Herein, a novel phosphorus-doped Bi2WO6 (PBWO) monolayer with oxygen vacancies was successfully synthesized through a facile one-step hydrothermal treatment using elemental red phosphorus (RP) as P source. Particularly, P atoms were doped into the lattice of Bi2WO6 in [BiO]+ layers via forming Bi-O-P bonds, and rich oxygen vacancies were introduced by phosphorus doping process. The optimized PBWO sample exhibits a remarkable visible-light photocatalytic simultaneous degradation of Cr(VI) and tetracycline hydrochloride activity, and a satisfactory photocatalytic nitrogen fixation rate of 73.6 μmol g−1 h−1 under simulated light irradiation, which is significantly enhanced compared to pristine BWO and phosphorus-containing heterostructures of BiPO4/Bi2WO6 and RP/Bi2WO6. Based on the results of various characterizations and DFT calculations, the superior photocatalytic performance of PBWO can be attributed to the synergistic effect of phosphorus doping coupled with oxygen vacancies, which improves the visible light absorption, modulates the band structure, introduces a defect level in the forbidden band, and effectively promotes the separation efficiency of photogenerated electron-hole pairs. The detailed photocatalytic mechanism was further proposed according to the radical capturing experiment and ESR technology.