Enhanced photoelectrochemical performance of Bi2WO6 via gradient doping and homojunction engineering for organic pollutant degradation

Abstract

Given the severe situation of environmental pollution and the potential of photoelectrochemical (PEC) technology in environmental protection, this study focuses on addressing the shortcomings of Bi₂WO₆ in PEC pollutant degradation. Specifically, issues such as severe photoregenerated electron-hole recombination and a small specific surface area are tackled through an innovative strategy combining gradient doping and surface modification. An innovative preparation method was employed to successfully synthesize the Bi₂WO₆ homojunction with gradient Fe doping and Cu element surface modification, which significantly enhances the absorption of visible light, generating more photoregenerated electron-hole pairs. Additionally, the gradient doping strategy effectively modulates the internal band structure of the material, forming a gradient potential field that facilitates carrier transport. In the Bi₂WO₆ homojunction structure, a built-in electric field is formed at the interface, further increasing the efficiency and stability of the catalytic reaction. Degradation experiments using Rhodamine B (RhB) as the target pollutant demonstrated that the Bi₂WO₆ homojunction thin film exhibits the highest degradation efficiency for RhB and maintains good stability after five cycles. Further trapping experiments revealed that holes (h⁺) and superoxide radicals (·O₂^-) are the primary active species during the degradation process. This study offers a new strategy for the development of PEC materials and provides strong support for the application of PEC technology in pollutant degradation.