Binary composites of (m-t) BiVO 4 /g-C 3 N 4 as an efficient S-scheme photocatalyst for bromocresol green degradation under visible light

Abstract Design and fabrication of heterojunction comprising the vanadates and g-C₃N₄ has drawn significant interests from the prospect of full-scale utilization of solar energy. In this context, the present work attempts the simple annealing step for the heterojunction formation between BiVO₄ and g-C₃N₄. Strikingly, BiVO₄ adopted pure monoclinic phase, which partially transformed to mixed monoclinic and tetragonal upon combination with g-C₃N₄. Such an intricate ternary phase was confirmed by X-ray diffraction technique and optical response measurements revealed the light absorption capacity in the significant portion of solar light. The electrochemical analysis confirmed the extended lifetime for the photogenerated charge carriers. The photocatalytic activity was investigated for the degradation of bromocresol green and composite performance exceeded compared to their pure phase counterparts. The radical scavenging experiments and alignment of band gap edges substantiated the formation of S-scheme heterojunction between BiVO₄/g-C₃N₄. It was proposed that the bulk recombination of charge carriers in BiVO₄ was greatly hindered due to the formation of homojunctions between the different crystal polymorphs of BiVO₄. On the other hand, interfacial charge carrier transfer process emerging from the interfacial electric field between BiVO₄ and g-C₃N₄ prompted for the S-scheme charge carrier transfer pathways.