Surface junctions between BiOBr and BiVO4 were synthesized. The BiOBr/BiVO4 with 1wt.% of BiOBr exhibited the highest photocatalytic activity in the degradation of RhB under visible-light irradiation. It was found that the highly efficient adsorption of RhB molecules via the electrostatic attraction between Br- and cationic N(Et)2 group played a key role for the high photocatalytic activities of BiOBr/BiVO4. This efficient adsorption promoted the N-deethylation of RhB and thus accelerated the photocatalytic degradation of RhB. Moreover, the metal-to-metal charge transfer (MMCT) mechanism was proposed, which revealed the concrete path paved with Bi-O-Bi chains for the carrier migration in BiOBr/BiVO4. The interaction between photoexcited RhB* and the Bi3+ in BiVO4 provided the driving force for the migration of photo-generated carriers along the Bi-O-Bi chains. This work has not only demonstrated the important role of efficient adsorption in the photocatalytic degradation of organic contaminants, but also developed a facile strategy to improve the efficiency of photocatalysts.
Keywords: Adsorption efficiency; N-deethylation; Photocatalysis; Redox potential; Surface junction.
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