Well-designed MXene-derived Carbon-doped TiO2 coupled porous g-C3N4 to enhance the degradation of ciprofloxacin hydrochloride under visible light irradiation

In this work, using melamine and MXene powder as precursors, NH4Cl as a template, a novel S-scheme heterojunction composite material g-C3N4/C-TiO2 was synthesized by a one-step calcination method. During the calcination process, the gas template NH4Cl played a dual role, which not only striped the massive g-C3N4 into porous flakes with a larger specific surface area but also striped the agglomerated MXene derivatives (C-TiO2) nanoparticles, making them bind more closely with g-C3N4. The charge separation efficiency and photocatalytic performance were greatly improved due to the formation of heterojunction and the larger specific surface area of the sample. Within 50 min, the g-C3N4/C-TiO2 exhibited high photocatalytic performance toward ciprofloxacin hydrochloride (CIP·HCl) with degradation efficiencies of 88.14% under visible light (λ ≥ 420 nm), which was 8.9 times higher than that of pure g-C3N4. In addition, we also used a series of characterizations to confirm the mechanism of S-scheme heterojunction and inferred the possible CIP photodegradation pathway.