Interface-engineered Co-MOF/CNT hybrid solar evaporator with symmetric–asymmetric design for concurrent solar water evaporation and energy generation

Simultaneous freshwater and electricity generation from solar evaporation presents a promising strategy for addressing water-energy scarcity. However, existing devices typically suffer from fixed functionality and compromised performance in either mode. This work introduces a novel symmetric-asymmetric solar evaporator enabling switchable harvesting of both freshwater and electricity on demand. Herein, the device leverages a reversible structural transition: symmetric configuration (indirect) for high-efficiency solar desalination 2.14 kg m −2  h −1 , photo-thermoelectric generation (Vout ∼308 mV, Iout ∼71 mA), and asymmetric configuration (direct) for spontaneous electricity generation (Vout ∼364 mV, Iout ∼78 mA), and an evaporation rate of 1.41 kg m −2  h −1 under 1 kWm −2 . This dual-mode operation is achieved through a simple, scalable nanomaterial design facilitating thermal-gradient behavior in both modes. State of-the-art experimental investigations were performed to assess the reproducibility, switching behavior, and long-term stability. The successful outdoor results under natural conditions enabled dual-mode solar evaporators as an effective strategy to harvest solar energy as well as waste heat for concurrent freshwater and electricity generation. More importantly, heat transfer simulations were effectively carried out to scrutinize the energy flow in dual-mode solar evaporators. This study demonstrates a highly effective approach to overcome the limitations of traditional solar interfacial evaporation and generate dual-mode in situ thermoelectricity and stable desalination under natural conditions.