Integrated copper-based Janus thermal system for efficient water harvesting around the clock

Abstract

Many regions across the globe are grappling with water scarcity issues, prompting the exploration of innovative water harvesting techniques. While the development of high-performance water harvesting materials has been widely documented, these technologies often rely on a singular source with limited efficiency. This study presents a dual-functional copper Janus system that facilitates continuous freshwater harvesting by integrating seawater desalination powered by solar energy during daylight hours and fog collection during night and morning time. The Janus system consists of a copper sheet and copper foam substrate, featuring superhydrophilic pores arranged on the superhydrophobic surface, as well as superhydrophilic flake-like structures made of soot-carbon particles, which are deposited on the framework of the copper foam. The fog collection rate of this system has been measured at 210.65 kg m⁻² h⁻¹, while the solar-driven evaporation rate of seawater under 1-sun conditions is reported at 1.44 kg m⁻² h⁻¹. The fog collection and evaporation efficiency have been enhanced by 28.72% and 183.27%, respectively. Furthermore, the system demonstrates strong and consistent performance even after repeated use, ensuring sustained water collection over prolonged periods. Therefore, this study presents a promising avenue for water collection technologies and offers valuable insights for the advancement of sustainable freshwater production methods.