Constructing MXene-derived Z-Scheme g-C₃N₄/Ti₃C₂TX/Ag₃PO₄ photocatalysts with enhanced charge transfer for aquatic organic pollutants removal

Photocatalysis was considered an efficient and environmentally friendly technology for wastewater treatment. In this study, MXene-derived g-C3N4/Ti3C2TX/Ag3PO4 as a novel Z-type heterojunction photocatalyst is successfully constructed, which shows great photocatalytic activity under visible light irradiation. Besides, Ti3C2TX could serve as an "electron bridge" between g-C3N4 and Ag3PO4, where the well-matched energy levels could be connected, improving the charge transfer rate remarkably. Meanwhile, PL, EIS and TPR results showed that Ti3C2TX possessed high electrical conductivity, which acted as an electron bridge between g-C3N4 and Ag3PO4 to improve the separation efficiency of photogenerated carriers, resulting in higher photocatalytic activity. Besides, g-C3N4/Ti3C2TX/Ag3PO4 exhibited extensive degradability to pharmaceutical and personal care products (PPCPs) and azo dyes including methylene blue (100.0%), rhodamine B (92.16%), tribromophenol (97.43%), ibuprofen (87.98%), doxycycline hydrochloride (57.97%) and levofloxacin (80.73%). In addition, g-C3N4/ Ti3C2TX/Ag3PO4 showed great recycling ability, no obvious difference was observed after five consecutive cycles of degradation experiments. Moreover, the reactive oxygen species (ROS) including hydroxyl radicals (center dot OH), holes (h(+)) and superoxide radicals (center dot O-2(-)) during the degradation process were confirmed by ESR analysis and trapping experiments, and a possible photocatalytic mechanism of g-C3N4/Ti3C2TX/Ag3PO4 heterojunction photocatalyst under visible light irradiation was also proposed.