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

Abstract

Dual metal cation doping has been demonstrated to be an effective approach for enhancing the photocatalytic activities of Bi₂WO₆. However, anion–cation dual doping of Bi₂WO₆ remains rarely reported. In this study, Ni and Cl anion–cation co-doped Bi₂WO₆ (NCB) samples 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, elemental composition, and chemical bonding environment of Bi₂WO₆. Photocatalytic tests show that NCB-2 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 ascribed to the improved hole mobility, increased generation of oxygen vacancies, enhanced light absorption, and a reduced band gap. Active species trapping experiments confirm that superoxide radicals (·O²⁻) and holes (h⁺) are the dominant reactive species in the photocatalytic degradation process. On the basis of the experimental results and mechanism analysis, a plausible photocatalytic degradation mechanism is proposed. This work provides a feasible strategy for designing anion–cation co-doped semiconductor photocatalysts toward the efficient removal of organic pollutants from wastewater.