Investigating the role of surface grafted Cr(III) on BiOIO3 as an efficient visible light photocatalyst for rapid degradation of RhB via superoxide radical pathway

Abstract A promising approach for constructing visible-light-responsive photocatalysts with superior activity is realized through the surface grafting of wide-band-gap semiconductors with earth-abundant elements. Consequently, this study demonstrates an efficient strategy to enhance the photocatalytic performance of BiOIO3 by tailoring its surface with Cr(III) clusters. A series of x-Cr(III)-grafted BiOIO3 photocatalysts (x = 0.5, 1.0, and 1.5 wt%) were synthesized through a facile hydrothermal method followed by an impregnation process. The structural, morphological, optical, and surface chemical properties of the prepared materials were systematically investigated. The characterization results confirm the successful grafting of Cr(III) species onto the BiOIO3 surface with intimate interfacial contact. The catalysts’ photocatalytic efficiency was assessed through the visible-light-driven detoxification of Rhodamine B (RhB). Notably, surface-modified BiOIO3 with 1.0 wt% Cr(III) exhibited 99% RhB degradation efficiency within 50 min, which is significantly superior to that of pristine BiOIO3. Reactive species trapping (quenching) experiments revealed that superoxide radicals play a dominant role in the degradation process. Based on these findings, a plausible photocatalytic degradation mechanism was proposed to elucidate the interfacial charge-transfer pathway and reactive species evolution. Ultimately, this study highlights surface-engineered BiOIO3 as a robust and sustainable photocatalyst for organic pollutant detoxification. The proposed strategy provides a viable pathway for environmental remediation and wastewater treatment under visible-light irradiation, offering a scalable and energy-efficient cleanup solution for real-world environmental applications. Graphical Abstract