A solution to break the salt barrier for high-rate sustainable solar desalination

Abstract

Solar steam generation (SSG) is a promising approach to address the global shortage of freshwater by seawater treatment, but commonly suffers from salt-accumulation related issues, drastically reducing the operational efficiency and lifetime of SSG systems. Herein, we propose a strategy for sustainable SSG from seawater, enabling powerful self-salt-discharge and self-water-pumping by constructing a closed loop between water and salt. As a result, besides an evaporation rate as high as 2.8 kg m⁻² h⁻¹ (under one sun), neither salt accumulation nor evaporation rate decline is observed upon long-term cycling of over one month or constant floating on seawater over eight months. Even upon continuous desalination in a highly concentrated solution (20 wt% NaCl) for over 400 h or under high-intensity irradiation for over 12 h, the high evaporation rate is successfully maintained. This work thus provides an effective solution for salt accumulation, addressing the top challenge for long-term sustainable desalination.