Novel 2D/2D S-scheme heterojunction photocatalyst for peroxymonosulfate activation enables ciprofloxacin ultrafast degradation: High-efficiency photogenerated carrier transport

Abstract

Organic pollutants, such as ciprofloxacin (CIP), are ubiquitously detected in wastewater. However, their removal remains a challenge for conventional wastewater treatment technologies. Photocatalysis and peroxymonosulfate activation coupling are considered a promising strategy for the removal of recalcitrant organic pollutants. However, identifying optimal photocatalysts that can effectively couple with peroxymonosulfate activation and induce synergistic degradation of organic pollutants remains a challenge to be addressed. In this work, a novel S-scheme inorganic–organic heterojunction BiVO4/Cu-TCPP (BC) was fabricated. In situ X-ray photoelectron spectrum showed that the strong internal electric field of the S-scheme heterojunctions enabled efficient carrier transport. The generated photogenerated electrons could activate the peroxymonosulfate, which further promoted the separation of the carriers. The BC-vis-peroxymonosulfate system achieved 93.1% ciprofloxacin removal in 10 min with apparent rate constants k of 0.2426 min−1, which is larger than most reported peroxymonosulfate systems. Electron paramagnetic resonance spectra and liquid chromatography mass spectrometry demonstrated that the synergistic coupling of S-scheme heterojunction with peroxymonosulfate activation significantly improved the catalytic activity of the reaction system and enabled rapid CIP removal via both radical and nonradical pathways. The BC-vis-peroxymonosulfate system demonstrated ultra-fast removal of other quinolone antibiotics and organic pollutants and strong environmental adaptability under various conditions, suggesting its great potential for practical application. This study provides new insights for the design of efficient S-scheme heterojunction coupled peroxymonosulfate activation for environmental remediation.