Designing interfacial built-in electric field-driven S-scheme cadmium tungstate/bismuth tungstate heterojunction for...

Herein, a hierarchical S-scheme heterojunction cadmium tungstate/bismuth tungstate induced by interfacial built-in electric field for efficiently enhanced photocatalytic performance was successfully constructed. Owing to the tight contact between cadmium tungstate nanorods and bismuth tungstate nanoflowers, it is demonstrated that the S-scheme heterojunction can be formed, which can efficiently enhance separation and transportation efficiencies of photoiduced charge carriers through an interfacial electric field, thus facilitating the generation of ·O₂^- and ·OH radicals. As a result, the optimized CdWO₄/Bi₂WO₆ heterojunction degraded 84% of sulfadiazine (SDZ) within 180 min, and the k_obs is 1.62 and 10.2 times higher than pure Bi₂WO₆ and CdWO₄, respectively. Meanwhile, the mineralization efficiency could get 54.39%. Even after four cycles, the degradation efficiency remained at 72.2%. Moreover, through a combination of density functional theory (DFT) calculations and liquid chromatography-mass spectrometry (LC-MS) analysis, the pathways of SDZ degradation involving S-N/N-C cleavage and Smile rearrangement were elucidated. These findings offer insights into the design of efficient S-scheme heterojunctions driven by engineering interfacial built-in electric field for the photocatalytic oxidization of SDZ.