Multiscale Preparation of Graphene Oxide/Carbon Nanotube-Based Membrane Evaporators by a Spray Method for Efficient Solar Steam Generation

Solar-driven interfacial evaporation is a sustainable and efficient way of producing clean water using solar energy. Currently, most studies on solar-driven interfacial evaporation are based on small-sized evaporators, and it is still a challenge to develop an efficient, simple, and general method for producing evaporators continuously and at a large scale. Herein, we develop a spray-based method for producing graphene oxide (GO)/carbon nanotube (CNT)-based membrane evaporators at various scales. This method enables production of membrane evaporators from a lab scale to an industrial scale. Great efforts have been made to optimize the preparation and properties of the membrane evaporators. A GO-CNT/paper membrane evaporator prepared under optimized conditions exhibits a high evaporation rate of 2.1 kg m–2 h–1 with a corresponding efficiency of 90.1% under one sun irradiation. The evaporator also has high properties of water desalination, purification, and disinfection. Natural lake water evaporation tests show a high water evaporation capacity of ∼8.2 kg m–2 on a sunny day, and the salinity in the obtained water (Na+ ions, 1.2 mg L–1) is below the WHO standards for drinkable water. Overall, an efficient, simple, and scalable method for producing high-performance membrane evaporators has been demonstrated.