Towards scalable visible-light photocatalysts: Multifunctional flexible BiOI–PVA/carbon fiber films with enhanced performance for environmental applications

This study describes a scalable strategy for the immobilization of hierarchical BiOI microflowers onto conductive carbon fiber substrates via a facile spray-deposition approach assisted by low-temperature polyvinyl alcohol (PVA) thermal crosslinking. Structural integrity and surface elemental composition of the samples were verified using X-ray diffraction (XRD) alongside X-ray photoelectron spectroscopy (XPS) Photoluminescence analysis indicated suppressed charge carrier recombination, morphological evaluation via scanning electron microscopy (SEM) confirmed the presence of well-defined hierarchical microflower architectures. UV–Vis spectroscopy showed a redshift in light absorption, attributed to interfacial interactions across the heterostructure. Photoelectrochemical evaluations elucidated the interfacial carrier dynamics, redox capabilities and band edge positions. The improved light-induced reactivity of the deposited films was validated through intermittent visible-light photocurrent profiling. The large-area films exhibited remarkable photocatalytic performance in multiple applications, including (i) breakdown of organic pigments (methyl orange and rhodamine B), (ii) detoxification of Cr(VI), and (iii) CO 2 reduction to useful chemical fuel vectors like formic acid driven by visible photon exposure. Additionally, the synthesized heterostructures exhibited excellent stability and reusability over consecutive cycles. Reactive oxygen species trapping experiments identified photogenerated holes as the primary drivers governing pollutant degradation. These findings highlight the successful development of BiOI–PVA/carbon fiber Schottky heterojunction films as efficient and scalable photocatalysts for environmental remediation and solar fuel generation.