Defect‐Engineered 3D Porous CeO _{2 − x} /MXene/rGO Aerogel for S‐Scheme Photocatalytic Degradation of Antibiotics, Heavy Metals, and PFAS:

ABSTRACT

The simultaneous remediation of emerging contaminants, including antibiotics, heavy metals, and per‐ and polyfluoroalkyl substances (PFAS), remains a critical challenge for groundwater sustainability. Herein, a defect‐engineered 3D CeO _{2 − x} /MXene/rGO ternary aerogel was fabricated through template‐free hydrothermal self‐assembly for efficient solar‐driven multi‐pollutant remediation. Advanced EPR, XPS, UPS, and Mott–Schottky analyses confirmed abundant oxygen vacancies (Ce ^{3 +} fraction ≈48.4%), Fermi‐level equilibration, and interfacial band bending, validating the S‐scheme heterojunction mechanism. Under simulated solar irradiation, the aerogel achieved an apparent rate constant of 0.0297 min ^{− 1} , nearly tenfold higher than pristine CeO ₂ . Synergistic superoxide radicals and deep valence‐band holes enabled near‐complete sulfamethoxazole degradation within 90 min, 98.2% Cr(VI) reduction, 81.6% TOC mineralization, and 47.0% defluorination of HFPO‐DA. The monolithic porous architecture ensured rapid mass transport, excellent retrievability, anti‐photocorrosion stability over eight cycles, and resilience in complex groundwater matrices. In‐situ DRIFTS verified oxidative C─F bond cleavage, while bio‐toxicity assays restored E. coli viability to 92.5% and Vigna radiata germination to 88.7%, demonstrating exceptional detoxification and environmental compatibility. Furthermore, the hierarchical rGO scaffold prevented MXene restacking and nanoparticle agglomeration, preserving active sites and multidirectional diffusion pathways. Efficient reactive oxygen species generation promoted simultaneous degradation, reduction, and mineralization processes, establishing a scalable, robust, and sustainable photocatalytic groundwater remediation platform.