Biomass-based Janus three-dimensional water evaporator for highly effective desalination and wastewater purification

An efficient Janus three-dimensional (3D) water evaporator with low-cost and energy-saving was developed for desalination and wastewater purification. The bottom layer of this water evaporator is composed of freeze-dried potato, which has an intricate 3D porous structure that can efficiently transport water through the capillary effect. Additionally, the freeze-dried potato also has the function of heat insulation, which can reduce heat loss and improve the light-to-heat conversion efficiency (η). The upper layer of the water evaporator is made of manganese-doped cobalt sulfide (Mn-CoSx) and agar hydrogel. The primary function of Mn-CoSx is to capture sunlight, which has full-spectrum absorption properties in the 200–2500 nm range. The role of agar hydrogel includes immobilizing Mn-CoSx, linking with freeze-dried potato, and transporting water molecules. Under one-sun irradiation, the water evaporator has a higher evaporation rate (1.75 kg m−2h−1) and η value (110.2%).