Manipulating a vertical temperature-gradient of Fe@Enteromorpha/graphene aerogel to enhanced solar evaporation and sterilization

Abstract

Water purification via solar interface evaporation technique is an attractive method to solve water resources shortage. Many efforts have been devoted to developing materials with high absorbance and various heat insulation devices to reduce heat loss while ignoring the heat loss caused by high temperature. To address this issue, a strategy is reported to breaking the evaporation limit by introducing a cold evaporation surface for additional environmental energy input. The evaporation system both eliminates thermal losses and maximizes utilizing the energy of the environmental energy and top evaporation interface vertically downward. The vertical hollow structure inner the lotus root-like three-dimensional (3D) aerogel based on iron-doped Enteromorpha/graphene and the nanopore structure formed by the stacked nanoparticles facilitate the water transport. The air barrier formed on the inner skeleton helps to reduce thermal conductivity and heat loss. By gradually increasing the side surface area of the cold evaporation to increase the temperature gradient difference in the vertical direction, the aerogel can realize the co-operation of the top surface interface evaporation and the side cooling evaporation. When the exposure height is 55 mm, the evaporation rate can be as high as 3.85 kg m⁻² h⁻¹ under 1 sun. In addition, aerogels show effective water purification capabilities, including effective isolation of inorganic ions, organic matter, oil in seawater, and sewage. More importantly, aerogels show excellent ability to extinguish bacteria under light, which provides a new idea for increasing water evaporation rate and realizing water purification.