Dual S-scheme Bi2MoO6/g-C3N4/Ag2MoO4 ternary heterojunction: Interfacial charge transfer, broadband spectrum, enhanced redox ability

Abstract

A ternary heterojunction bearing Bi₂MoO₆ and g-C₃N₄ is deposited on Ag₂MoO₄ for the photocatalytic degradation of sulfamethoxazole (SMX) antibiotic. Though the hydrothermal synthesis is non-directional, the dual S- scheme heterojunction formation is governed by the g-C₃N₄ serving as an electron bridge between Bi₂MoO₆ and Ag₂MoO_4. The potent strong interaction with both Bi₂MoO₆ and Ag₂MoO₄ facilitates high oxidation and reduction potential. The optimized Bi₂MoO₆/g-C₃N₄/Ag₂MoO₄ heterojunction with extended visible light absorption exhibits 96 % SMX degradation efficiency within 240 min of irradiations. The dual S-scheme configuration endows in-built electric field with vigorous driving force for charge carrier separation. The charge transfer mechanisms were validated by the photoluminescence results. Bi₂MoO₆/g-C₃N₄/Ag₂MoO₄ heterojunction demonstrates pseudo-first order kinetics with 0.143 kmin⁻¹ for SMX degradation and ternary photocatalyst 83 % degraded SMX after successive five cycles. In the formed dual S-scheme Bi₂MoO₆/g-C₃N₄/Ag₂MoO₄heterojunction, ^●OH and ^●O₂⁻ radicals were the main reactive species for SMX degradation. This research contributes to the formation of stable multicomponent photocatalytic systems.