Pyramid-shaped solar evaporator with high-efficient interfacial evaporation and salt harvesting capability

Solar-driven interfacial evaporation shows significant potential for addressing challenges associated with freshwater shortages and environmental pollution. In this study, a series of pyramid-shaped solar evaporators were fabricated to achieve highly efficient solar interfacial evaporation. The optimized triangular pyramid evaporator exhibits exceptional adaptability and stability in seawater desalination and wastewater purification, thanks to its excellent light capture and photothermal conversion capacity, controlled water supply, effective thermal management, and energy input from the environment. It maintains a high evaporation rate and energy efficiency even in highly concentrated saltwater and strongly acidic or alkaline solutions. The 3D conical evaporation structure promotes top-preferential crystallization, directing the crystallization process towards the apex and facilitating efficient spatial salt harvesting. The collected condensate meets the drinking water requirements set by the World Health Organization (WHO) and the US Environmental Protection Agency (EPA). Under outdoor evaporation conditions, the evaporator achieves a daily freshwater production of 24.93 and a salt production of 2.09 kg m−2 d−1, fully satisfying the needs of a typical three-person household. Our microstructure control strategy for enhancing solar interfacial evaporation offers valuable insights and inspiration to researchers aiming to improve the performance of 3D solar evaporators.