Synergetic photocatalytic activation of persulfate by Ti3C2/g-C3N4 for sterilization and antibiotic degradation

Abstract

Photocatalytic persulfate (PS) activation holds promise for addressing antibiotic contamination and pathogenic microorganisms in wastewater, yet its efficiency is limited by rapid charge recombination in conventional photocatalysts. Herein, we engineered a Ti₃C₂/g-C₃N₄ heterojunction through controlled thermal exfoliation. The introduced Ti₃C₂ acts as an electron-conducting bridge to suppress charge recombination while simultaneously serving as a PS activation site. Under visible light, the optimized heterojunction achieved complete inactivation of E. coli within 20 min and 99.3 % viability reduction of S. aureus within 30 min. It also demonstrated enhanced photocatalytic removal efficiencies of 98.0 % for sulfamethoxazole (SMX) and 97.7 % for sulfadiazine (SD) within 20 min, corresponding to 9.3-fold and 2.0-fold improvements over pristine g-C₃N₄, respectively. Mechanistic investigations revealed that the synergistic interplay between the CN charge transfer bridges in the Ti₃C₂/g-C₃N₄ heterojunction and the Ti₃C₂-mediated electron shuttling through ≡Ti(III)/≡Ti(IV) redox cycles facilitate PS activation and drives the continuous generation of reactive species (¹O₂, ·O₂⁻, and h⁺). Transcriptomic analysis further identified disrupted biosynthesis pathways and compromised membrane integrity as key contributors to bacterial inactivation. This study provides theoretical insights for the rational design of efficient MXene-based heterojunction catalysts for photo-assisted activation of PS to control pathogenic microorganisms and remove antibiotics.