Nickel and chlorine dual doping Bi₂WO₆ for efficient photocatalytic degradation of RhB

Abstract

Dual metal cation doping has been demonstrated to be an effective approach for enhancing photocatalytic activities of Bi2WO6，Howeverr anion-cation dual-doping of Bi2WO6 remains rarely reported. In this study, Ni and Cl anion-cation co-doped Bi2WO6 (NCB) were successfully synthesized via a facile hydrothermal method. The as-prepared samples were systematically characterized by X-ray diffraction (XRD), Field Emission Scanning Electron Microscopy (FESEM), Energy Dispersive Spectroscopy (EDS), X-ray Photoelectron Spectroscopy (XPS), Fourier transform infrared (FTIR) and Raman spectroscopy. Characterization results reveal that Ni/Cl dual doping effectively modulates the crystal structure, morphology, valence states and elemental composition, and chemical bonding environment of Bi2WO6. Photocatalytic tests show that NCB exhibits excellent photocatalytic activities: the degradation efficiency of Rhodamine (RhB) reaches 93.56 % within 70 min, and its rate constant k is 2.27 times higher than that of pure Bi2WO6. The enhanced photocatalytic performance can be mainly ascirbed to the improved hole mobility, increased generation of oxygen vacancies, enhanced light absorption, and reduced band gap. Active species trapping experiments confirm that superoxide radical (·O2-) and hole (h+) are the dominant reactive species in the photocatalytic degradation process. On the basis of experimental results and mechanism analysis, the plausible photocatalytic degradation mechanisms is proposed. This work provides a feasible strategy for designing of anion-cation co-doped semiconductor photocatalysts toward efficient removal of organic pollutants from wastewater.‌