Nature-inspired pyramid-shaped 3-dimensional structure for cost-effective heat-localized solar evaporation with high efficiency and salt localization

Abstract

• A nature-inspired material for heat-localized solar evaporation is proposed. • The durian-based evaporator forms a hierarchical structure for solar absorption. • An extremely high solar absorption of over 99% is achieved. • A high evaporation rate of 1.66 k g m - 2 h - 1 under one sun illumination is achieved. • The unique structure could enable localized salt localization for long-term operation. Solar evaporation by heat localization has drawn great interest in recent years to ease the global problem of freshwater shortage. Although many evaporators have been proposed, there is still great potential to develop extremely cost-effective solar evaporators with both high evaporation efficiency and salt resistance. Here, we propose a heat-localized solar evaporator based on wasted durian shells. After carbonization and polypyrrole deposition, this durian shell-based evaporator achieved a 99% absorption in the whole solar spectrum, owing to its hierarchical solar absorption structure from macroscale to nanoscale. We further make the bottom surface of the evaporator to be curved to reduce the conductive heat loss, and the structure-optimized durian shell-based evaporator achieved a high evaporation rate of 1.66 k g m - 2 h - 1 and evaporation efficiency of 91% under the solar intensity of 1000 W m - 2 . In addition, the pyramid-shaped structures on the surface of durian shells could enable localized salt crystallization, which enables long-term operation of such evaporators in the saline environment. This work presents an attempt with significance in developing extremely cost-effective materials for highly efficient heat-localized solar evaporation.