S-scheme BiOBr/CoFe-LDH heterojunction with modulated Fe d-band center for synergistic photocatalysis-peroxymonosulfate activation toward ciprofloxacin degradation

An interface-engineered S-scheme BiOBr/CoFe-LDH heterojunction photocatalyst was fabricated via a facile one-pot hydrothermal method to boost CIP degradation. The crystal structure, morphology, optoelectronic properties and interfacial charge transfer behavior were systematically characterized by XRD, TEM, XPS, photoelectrochemical measurements and density functional theory (DFT) calculations. The optimized 5-BOB/LDH/PMS/Vis system achieved ∼90% CIP removal within 60 min for 20 mg L −1 CIP solution, with an apparent rate constant 1.7-fold and 11.3-fold higher than those of pristine CoFe-LDH and BiOBr, respectively. The catalyst exhibited excellent practical applicability: it retained 81.5% activity after 5 consecutive cycles, maintained high degradation efficiency over a broad pH range (4–11) and showed universal degradation capability toward tetracycline, rhodamine B, acetaminophen and sulfadiazine. Mechanistic studies revealed that the constructed S-scheme heterojunction not only suppressed charge carrier recombination but also upshifted the d-band center of Fe species, enhancing PMS adsorption and accelerating the synergistic redox cycle between Co and Fe active sites. This work provides a rational design strategy for high-performance PMS-activating photocatalysts and demonstrates great potential for the advanced treatment of antibiotic-containing wastewater.