Synergistic structural and electronic engineering of hollow BiOCl via carbon nanospheres and in-situ CQDs for efficient visible-light photodegradation of organic pollutants

A novel dual-function carbon-mediated strategy was developed to engineer BiOCl photocatalysts with integrated structural and electronic regulation. Glucose-derived carbon nanospheres (GCS) simultaneously served as renewable, low-cost templates that transformed BiOCl from two-dimensional lamellae into three-dimensional hollow microspheres and as carbon sources for the in-situ generation of carbon quantum dots (CQDs). GCS primarily directed hollow architecture formation and induced oxygen vacancies, thereby narrowing the bandgap and enhancing carrier mobility, whereas in-situ CQDs acted as electron acceptors and charge mediators that broadened visible-light absorption and promoted efficient charge separation. The optimized 0.3 %-GCS-BOC photocatalyst achieved 99 % Rhodamine B (RhB) removal within 40 min and 85 % tetracycline (TC) removal within 180 min, while maintaining 96.7 % efficiency after five cycles, confirming its stability. Key intermediates, including de-ethylated and ring-opened species, were identified, supporting stepwise pathways toward mineralization. Oxygen vacancies facilitated electron transfer, while CQDs suppressed charge recombination, with superoxide radicals (·O 2 − ) confirmed as the dominant reactive species. Environmental safety was validated by leaching tests showing negligible release of chloride and carbon species. The 0.3 %-GCS-BOC photocatalyst also showed strong applicability in real wastewater, achieving TOC removal efficiencies comparable to those in pure RhB solutions. This catalyst exhibited superior efficiency, durability, and environmental compatibility. This work highlights the synergistic novelty of GCS templating, in-situ CQD formation, and oxygen vacancy co-engineering, providing mechanistic insights and a scalable route for the development of sustainable photocatalysts for wastewater treatment. • GCS directed the self-templated formation of hollow flower-like BiOCl structures. • In-situ formation of CQDs and lattice modulation introduced abundant OVs. • OV density was tunable via carbon nanosphere content control. • Bandgap narrowing and enriched OVs improved light harvesting and charge transport. • 0.3 %-GCS-BOC composite showed excellent RhB and TC degradation.