α-FeOOH-Intercalated TiCT MXene as a new and stable heterogeneous Fenton catalyst for caffeine degradation in water

This study demonstrates a simple and scalable synthesis of α-FeOOH (goethite) intercalated Ti 3 C 2 T x MXene through TMAOH treatment, targeting efficient degradation of emerging micropollutants in wastewater via an advanced oxidation process (AOP). Such a α-FeOOH-intercalated MXene stabilizes heterogeneous Fenton-based reactions which usually suffer from decreased efficiency over time due to Fe leaching, thus highlighting the novelty of the work. The successful integration of goethite particles in the MXene interlayer space was evidenced by X-ray diffraction (XRD), Fourier-transform infrared spectrometer (FTIR) and Transmission Electron Microscopy (TEM) analysis. X-ray photoelectron analysis (XPS) revealed notable surface oxidation along with minor TiF x and TiO 2-x F x impurities formed via TMAOH treatment. Increased concentration of surface functional groups along with enhanced BET area (71.2 m 2 g -1 ) and porosity after TMAOH treatment enabled complete degradation of caffeine in ⁓ 90 minutes, by activation of peroxymonosulfate (PMS) under UVA light. Scavenging experiments, electron paramagnetic resonance (EPR) and XPS analysis indicated the degradation mechanism driven by Fenton-based reactions, electron transfer and interfacial surface charge transfers, with hydroxyl ( • OH) and sulfate ( SO 4 • − ) radicals identified as predominant reactive oxygen species (ROS). The assessment of the α-FeOOH-intercalated MXene as stable Fenton catalyst was confirmed with minimal iron leaching (3.07 wt. %) during catalytic reactions and robust reusability over ten cycles, thus being more efficient and sustainable than conventional Fenton-based catalysts. Post-reaction XRD,FTIR and TEM analyses further confirmed excellent structural stability of the new catalyst. These findings establish α-FeOOH-intercalated Ti 3 C 2 T x MXene as a promising and durable catalyst for heterogeneous Fenton-based reactions applied to wastewaters treatment. Visible-light PMS activation by α-FeOOH/Ti 3 C 2 T x MXene for efficient caffeine elimination.