Full-Spectrum-Activated Confining Aerogel With Dual-Scale Photothermal Regulation for Ultra-Efficient Low-Temperature Water Purification.

Cold aquatic environments severely limit photocatalytic remediation due to suppressed interfacial kinetics and rapid heat loss. Here we report a floating, confining aerogel that couples broadband light absorption with dual-scale photothermal regulation. The confining aerogel immobilizes FBBov@MoS2 catalytic units within a hierarchically porous exoskeleton, enabling full-spectrum (UV-Vis-NIR, 320-2500 nm) harvesting and the formation of spatially confined photothermal domains. Under full-spectrum irradiation the construct simultaneously generates long-lived microscale hotspots at the catalyst-liquid interface (> 19.5°C increase) and macroscopic heat accumulation at the air-water boundary (ΔT ≈ 9.5°C at 10°C), producing a synergistic photothermal field that accelerates charge separation and surface redox chemistry. Consequently, the confining aerogel achieves 99.1% tetracycline degradation within 120 min at 10°C and retains high activity (≈ 92% removal) even at 6°C. Mechanistic probes identify •O2 - and •OH as dominant reactive oxygen species and confirm that UV initiates high-energy carrier pathways, visible light sustains carrier flux, while NIR enforces photothermal promotion-their coupled action yields a nonlinear performance enhancement. The material also demonstrates broad pollutant scope, excellent durability over 28 days, and effective operation in real river water. This dual-scale photothermal-photocatalytic coupling constitutes a generalizable design principle for high-performance photocatalysis in cold environments.