Highly salt-resistant and all-day solar-driven interfacial evaporator based on Janus CS@Fe3O4/SA-MF

The escalating global freshwater crisis demands urgent development of high-performance desalination technologies. Solar-driven interfacial evaporation (SIE) has emerged as an energy-efficient and environmentally sustainable technology for seawater purification, yet its practical adoption remains hindered by persistent challenges: performance degradation under prolonged operation, and inherent discontinuity of solar energy day and night. Herein, we propose a novel all-day solar-driven interfacial evaporators by solar-thermoelectric cogeneration system, which synergistically integrates a magnetically responsive Janus CS@Fe₃O₄/SA-MF evaporator with thermoelectric generator (TEG) and solar cells. The Janus evaporator fabricated by a facile two-step dip-coating methodology, features engineered asymmetric wettability (contact angle contrast: 152.5° vs. 0°) and exceptional broadband absorption (>99% across 250–2500   nm). Under solar irradiation (1 sun), the system achieved an exceptional evaporation rate of 2.678   kg·m⁻²·h⁻¹ over 10   hours with 96% efficiency, while simultaneously generating electricity according to the Seebeck effect (maximum output: 116   mV, 6.32   mA). Remarkably, due to the Peltier effect, the energy storage of the solar cell enabled sustained nocturnal operation, maintaining an evaporation rate of 1.088   kg·m⁻²·h⁻¹ (7 times of pure water). The synergistic design utilizes solar evaporation during the day and energy conversion at night to effectively overcome the barrier of dependence on sunlight. This work proposed cogeneration strategy opens new avenues for sustainable freshwater production and decentralized energy supply in water-energy nexus applications.