A bionic lotus-leaf-shaped evaporator with zonal wettability and high salt resistance

Abstract

Interfacial solar vapor generation (ISVG) is a promising and environmentally friendly desalination strategy to solve the global water crisis. However, producing a long-lasting evaporative system, which has effective salt resistance, heat management and solar energy utilization, remains a major challenge. Here, we propose a lotus-leaf-shaped carbon/cotton fabric-based evaporator with drainage strips (L-CCF/D). The lotus-leaf-shaped invert cone structure of the evaporator is designed to effectively localize heat to reduce heat losses and increase the times of light reflection to improve the utilization of solar energy. The drainage strips are introduced to form a zonal wettability to avoid salt crystals deposition, and draw out highly concentrated brine for long-lasted application. The designed evaporator has the evaporation rate of 2.45 kg m^-2 h⁻¹ in deionized water at a light intensity of 1 kW m⁻², and also shows long-term stability in highly concentrated brine, which has the average evaporation rate of 2.17 kg m^-2 h⁻¹ in 10 wt% NaCl solution for 6 h. The evaporator has a fresh water yield of 8.05 kg m⁻² in the outdoor experiment. This unique design with drainage strips ensures the long-term stability of the evaporator in actual seawater applications, providing a broad application prospect for solar water treatment.