Tetragonal/orthorhombic phase Bi2WO6 homojunction for photoelectrochemical degradation of rhodamine B with high efficiency

Photoelectrochemical (PEC) degradation of organic pollutants to CO ₂ and H ₂ O is a promising strategy to solve the growing environmental problems. Bismuth tungstate (Bi ₂WO ₆ ) has attracted much attention due to its good chemical stability and moderate conduction band valence band position. However, the PEC activity of Bi ₂WO ₆ catalysts is greatly limited due to its rapidly complex electron-hole. This article reports a rational low-cost design that successfully prepares tetragonal/orthorhombic Bi ₂WO ₆ homojunction on FTO conductive glass substrates through a simple two-step solvothermal method, significantly enhancing the PEC performance. The study investigated the effectiveness of photoelectrochemical degradation of the recalcitrant organic pollutant Rhodamine B (RhB) and conducted an in-depth exploration of the photoelectrocatalytic reaction process and mechanism. The experimental results indicate that the homojunction achieves a degradation rate of up to 100 % for the recalcitrant organic pollutant RhB within 30 minutes, significantly surpassing that of single-phase Bi ₂WO ₆, and at the same time the sample maintains good stability after five cycles of operation. Further analysis of the capture experiments indicates that holes (h ⁺ ) and superoxide radicals (·O ₂ ^⁻ ) are the primary active species responsible for RhB degradation. This study not only provides new insights into the design of high-efficiency photoelectrode, but also offers new solutions for environmental pollution control.