Dual‐Bionic Water‐Electricity Cogeneration Systems Integrating Efficient and Matched Photothermal and Evaporative Performances

ABSTRACT Water‐electricity cogeneration systems based on photothermal and evaporative interfaces offer a promising approach to green power generation and freshwater production. System efficiency depends not only on photothermal conversion and evaporation performance but also on the often‐overlooked matching between these processes. Here, we present a dual‐bionic water‐electricity cogeneration system that integrates photothermal and evaporative interfaces inspired by the robust photon‐trapping effect of butterfly wings and capillary effect of sarracenia, respectively. This design enhances both individual components and achieves an optimal match between heat transfer and evaporation, significantly improving overall solar energy utilization efficiency. Under one‐sun irradiance, the temperature difference between the photothermal and evaporative interfaces reaches 7.4°C, generating an open‐circuit voltage of 245 mV and a power density of 5.56 W m −2 , outperforming most comparable systems. Furthermore, the system achieves a water evaporation rate of 2.88 kg m −2 h −1 , and demonstrates long‐term stability during seawater desalination by effectively suppressing salt deposition. Stacking thermoelectric modules can further amplify the power output without the need for strict sun‐facing alignment, which is quite in contrast to conventional photovoltaic systems. These findings offer a practical pathway for developing highly efficient water‐electricity cogeneration systems.