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Emerging solar interfacial evaporation offers the most promising response to the severe freshwater crisis. However, the most challenging bottleneck is the conflict between resisting salt accumulation and maintaining high evaporation performance since conventional salt‐resistant evaporators enhance water flow to remove salt, leading to tremendous heat loss. Herein, an ion‐transfer engineering is proposed via a Janus ion‐selective hydrogel that enables ion‐electromigration salt removal, breaking the historical dependence on water convection, and significantly lowering the heat loss. The hydrogels drive cations downward and anions upward, away from the evaporation surfaces. An electrical potential is thus established inside the evaporator and salt in 15 wt% brine is removed stably for seven days. A record‐high evaporation rate of 6.86 kg m−2 h−1 in 15 wt% brine, 2.5 times the previously reported works, is achieved. With the from‐scratch salt‐resistant route, comprehensive water‐thermal analysis, and record‐high performance, this work holds great potential for the future salt‐resistant evaporators.

Solar interfacial evaporation holds great potential for desalination. Currently, abundant and renewable biomass appears to be the most sustainable evaporator candidate for addressing environmental and energy challenges. However, the widespread use of biomass‐based evaporators is hampered by the formation and deposition of salt on the evaporation surface. Herein, we present a hierarchical photothermal aerogel inspired by the leaves‐on‐stems architecture in pristine plants. It is formed with microchannels severing as stems and nanospikes as leaves. Microchannels with large pores enable quick brine replenishment, while numerous nanospikes increase the available surface area for vapor generation. In contrast to the macro‐scale salt‐resistant design, which ruins the overall structure of the evaporator, we modified the microchannel structure within the biomass, allowing the biomass evaporator to effectively resist salt while maintaining efficient evaporation performance. The unique hierarchical micro‐nano structure of this photothermal aerogel allows it to achieve a high evaporation rate of 1.78 kg m−2 h−1 under 1 sun and a continuous evaporation time of 100 h without salt deposition in a high‐salinity brine (15 wt%), outperforming most previously reported evaporators derived from biomass. Additionally, the anti‐biofouling capacity of the evaporator is effectively demonstrated for long‐term operation through the development of an enhanced freshwater collection prototype, highlighting the potential for sustainable off‐grid solar desalination.

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