Constructing g-C₃N₄/Bi₂MoO₆ heterojunctions for efficient visible-light-driven RhB degradation

Single-component photocatalytic materials generally exhibit poor utilization of visible light and inefficient charge separation. To address these limitations, a series of g-C₃N₄/Bi₂MoO₆ heterojunction composites were fabricated via a facile stirring-assisted heating-evaporation method. Structural and spectroscopic characterization revealed intimate interfacial coupling between g-C₃N₄ and Bi₂MoO₆ accompanied by evident interfacial electronic interaction. Under visible-light irradiation, the 30% g-C₃N₄/Bi₂MoO₆ composite exhibited the highest catalytic activity toward Rhodamine B (RhB) degradation, with an apparent rate constant of 0.01922 min^-1. This rate constant was 4.14 and 7.09 times higher than those of pristine g-C₃N₄ and Bi₂MoO₆, respectively. Photoelectrochemical measurements further confirmed that the constructed heterojunction significantly accelerated charge-carrier kinetics and mobility while effectively suppressing electron-hole recombination. Radical-trapping experiments combined with band-structure analysis indicated that holes (h⁺) are the dominant active species for RhB oxidation, with ˙O₂ ^- serving as a secondary reactive species and ˙OH contributing only marginally. The enhanced photocatalytic activity arises from efficient interfacial charge separation and directional charge migration.