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@MoS 2 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 (Δ T ≈ 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 •O 2 − 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.