Photothermal–Magnetocaloric Coupled Evaporators for Actively Adjustable Water Evaporation and Oil–Water Purification in Complex Environments

Solar‐driven interfacial evaporation is a sustainable approach for freshwater production; however, its reliability is limited by the fluctuating solar intensity and complex water contaminants. This study produces a synergistic strategy that integrates magnetocaloric‐mediated thermal compensation within a hierarchically structured aerogel. Iron‐based nanoparticles derived from waste self‐heating patches are incorporated into a konjac glucomannan/polyvinylpyrrolidone (KPF) aerogel with vertically aligned channels, yielding an actively adjustable photothermal–magnetocaloric coupled evaporation system capable of operating under diverse conditions. The KPF evaporator achieves an evaporation rate of 4.5 kg m −2 h −1 under one‐sun illumination, increasing to 5.6 kg m −2 h −1 upon activation of an alternating magnetic field. Notably, under overcast and low‐light conditions, comparable evaporation performance is maintained through magnetic field‐induced energy compensation. Molecular dynamics simulations and Raman spectroscopy reveal that magnetocaloric heating disrupts the ordered hydrogen‐bond network of water, increasing the free water content and facilitating evaporation. The intrinsic underwater superoleophobicity of the KPF aerogel enables a coupled interception and evaporation mechanism for high‐concentration oily wastewater, achieving a purification efficiency of 99.9%. Moreover, the magnetocaloric‐enhanced Marangoni flow promotes salt ion migration, ensuring long‐term stability in high‐salinity environments. This dual‐response strategy provides a universal platform for designing actively adjustable and efficient water treatment systems.