Photothermal Heat‐Storage Nanostructure‐Assisted Water‐Electricity Cogeneration System with Dual Solar Energy Inputs and High‐Efficiency Heat Utilization

Abstract Conventional water‐electricity cogeneration systems combining solar‐driven interface evaporators (SIEs) and solar‐thermal‐electric generators (STGs) suffer from limited overall efficiency due to their reliance on a single solar energy input. To address this limitation, a novel system is developed with dual solar inputs that simultaneously utilizes conduction heat and steam enthalpy. Au/Ag‐Pd nanostructures loaded with phase‐change material (Au/Ag‐Pd/PCM) are designed as visible‐light absorbers, enabling photothermal storage and reduced thermal losses. By constructing Janus nano/micro structures of Au/Ag–Pd/PCM/sulfonated polystyrene on a water supply layer, optimal balance between thermal energy and water content within the SIE is achieved. The optimized SIE is coupled with a STG to form the complete cogeneration system through heat‐recovery pathways. Benefiting from the dual solar inputs and efficient heat utilization, the system demonstrates outstanding performance metrics including an evaporation rate of 3.68 kg m −2 h −1 , a solar‐to‐vapor efficiency of 104.82%, and a maximum power density of 1.55 W m −2 in 3.5 wt.% NaCl brine under 1 sun. Outdoor testing of the scaled‐up system confirms stable freshwater production (≈15.5 kg m −2 daily) and scalable power generation. This work offers new insights into energy input design and heat recovery mechanisms for enhancing coupled water and electricity generation.