Partially oxidized MXenes-derived C-TiO₂/Ti₃C₂ coupled with Fe-C₃N₄ as a ternary Z-scheme heterojunction: Enhanced photothermal and photo-Fenton performance

Photo-Fenton reaction combining the photocatalytic reaction and Fenton reaction showed excellent degradation performance. However, it highly demanded the catalysts to display outstanding activity in these two reactions. Herein, Fe-doped carbon nitride/MXenes-derived C-TiO₂/Ti₃C₂ (Fe-C₃N₄/Ti₃C₂/C-TiO₂) was prepared via two steps: Fe-C₃N₄ and Ti₃C₂ were assembled via face-to-face attachment, following by in-situ partial oxidation of Ti₃C₂ to C-TiO₂. DFT predicted a Z-scheme charge transfer routine via metallic Ti₃C₂ as bridge, which was verified by EPR and radical trapping experiments. Additionally, PDOS calculation revealed the charge density around the doped-Fe atoms was remarkably increased, leading to better H₂O₂ activation, which was experimentally confirmed by high yield of ^•OH. Moreover, Fe-C₃N₄/Ti₃C₂/C-TiO₂ possessed the high photothermal effect to accelerate the surface reaction. By taking advantage of these merits, the degradation rate of Fe-C₃N₄/Ti₃C₂/C-TiO₂ was at least 4.2 times higher than the reference catalysts. Our work provided an insight toward the g-C₃N₄/TiO₂-based photo-Fenton catalysts with high performance.