Reusable reduced graphene oxide based double-layer system modified by polyethylenimine for solar steam generation

Surface plasmon resonance effects of nanoparticles, generating local hot spots in a water-air interface under sunlight irradiation to drive water into steam, can realize the highly efficient conversion of solar energy. Here, we develop a novel solar steam generation system with double-layer structures, of which the top reduced graphene oxide (rGO) sheets as a light-to-heat conversion layer and the bottom mixed cellulose esters (MCE) membrane as a porous supporting layer. The double-layer system (rGO/MCE) connected by polyethylenimine can convert the absorbed solar energy to heat energy at a water-air interface to enable efficient evaporation (∼60%) under only 1 kW/m2 irradiation. Contrast experiments under a light density of 4 kW/m2 showed that the rGO/MCE membrane achieved the highest evaporation efficiency of 71.8 ± 3%, and its evaporation rate is 4.3 times higher than that of pure water. Cycling tests confirmed that the system still maintained a stable performance over 15 cycles under same illumination conditions. Excellent mechanical stability, low cost, simple preparation and reusability of the rGO/MCE membrane are suitable for a wide range of practical applications in large-scale solar steam generation, sterilization of waste, seawater desalination.

A novel rGO/MCE double-layer system was developed for solar steam generation with high water evaporation efficiency up to 60% under only 1 kW/m2 solar irradiation.237