Bio-derived carbon sphere-modified BiOCl/BiOI heterostructures for photocatalytic treatment of real wastewater

Bio-derived carbon sphere-modified BiOCl/BiOI heterostructures were synthesized via a one-pot solvothermal route to achieve simultaneous interfacial phase alignment and defect engineering. The glucose-derived carbon spheres (GCS) acted as a morphogenetic soft template, inducing a structural evolution into 3D hollow spheres while generating in situ carbon quantum dot (CQD)-like domains. These nanoscale carbon domains establish continuous interfacial charge-transfer channels, suppressing photogenerated carrier recombination. The optimized GCS–BiOCl 0.85 I 0.15 composite exhibited a narrowed bandgap, reduced charge-transfer resistance, and enhanced photocurrent density. The composite achieved enhanced total organic carbon (TOC) removal for both rhodamine B and tetracycline compared to pristine BiOCl. When evaluated in primary-treated municipal wastewater matrices across different batches, the catalyst maintained robust performance, achieving approximately 50% TOC removal within 40 min without substantial photocorrosion or significant elemental leaching. Post-treatment phytotoxicity assays using Lactuca sativa and Vigna radiata confirmed a significant reduction in effluent toxicity. This work demonstrates the potential of integrating halogen-modulated heterojunctions with carbon-assisted defect tuning for realistic wastewater remediation, while acknowledging the need for further synthesis optimization to enhance overall process sustainability.