Controlled Self‐Assembly and Photo‐Thermal Activation of Viologen‐Based 2D Semiconductors for Dual‐Function Energy Management in All‐Weather Applications

Abstract Solar thermal technology offers a promising solution to water scarcity; however, the continuous operation of solar evaporators remains challenging due to sunlight's intermittent availability. Herein, an alternative strategy is proposed to achieve dual‐functional energy management of photo‐thermoactivated viologen T semiconductors for enhanced solar water evaporation, water‐enabled electricity generation, and electrothermal evaporation. A sequential cyanide‐bridged layer‐directed intercalation approach is developed, where infinitely π‐stacked, redox‐active N‐methyl bipyridinium cations with near‐planar structures are sandwiched between cyanide‐bridged Mn II –Fe III . The extended absorption range of 95% is achieved through radical–π interactions that occur within the continuously π‐stacked N‐methyl bipyridinium units upon thermal activation. The photo‐thermoactivated Mn II –Fe III compounds anchored charcoal mask (Mn II –Fe III @CM) with a sided evaporation structure and controllable water transfer, offering a high evaporation rate of 2.39 kg m −2 h −1 under one sun (1 kW m −2 ) illumination. As an energy nanogenerator, the output voltage and current of Mn II –Fe III @CM can reach up to ≈480 mV and ≈60 µA cm −2 under ambient conditions. Furthermore, storage of electrical energy from Mn II –Fe III @CM using energy storage devices is expected to enable all‐weather evaporation by electric heating due to unsustainable sunlight, providing a unique technology for seawater desalination and offshore work platform energy access.