All-Weather Dual-Energy-Driven Sandwich-Structured Composite Membrane for Continuous Desalination and Water Purification

Abstract

Interfacial solar evaporation has emerged as an energy-efficient approach for seawater desalination. Nevertheless, the practical application of conventional solar evaporators remains constrained by their strong dependence on sunlight, resulting in markedly reduced evaporation performance under cloudy conditions or at night. To address this limitation, a dual-energy-driven composite membrane capable of operating under either solar or electrical energy input was developed in this work for continuous all-weather desalination. The membrane was designed with a sandwich-structured architecture, in which a carbon fiber layer served as the conductive intermediate layer, while the outer layers consisted of Ketjenblack and MAH-grafted SEBS fabricated through a solution casting process. By integrating photothermal and electrothermal conversion within a single membrane, the composite membrane exhibited efficient water evaporation performance under different energy-input conditions. Under one-sun irradiation, the evaporation rate reached 2.789 kg m–2 h–1, and under an external voltage of 3.5 V, the evaporation rate reached 3.768 kg m–2 h–1. In addition, the membrane demonstrated strong environmental tolerance toward complex water environments, including dye-containing solutions as well as strongly acidic and alkaline media. This work provides a practical strategy for developing dual-energy-responsive evaporation systems for continuous freshwater production under variable environmental conditions.