Graphene-Based Stand-Alone Networks for Efficient Solar Steam Generation

Solar steam generation is one of the promising methods to obtain freshwater from wastewater and saline water. Here, using graphene/graphene oxide composite nanosheets and polyvinyl alcohol as raw materials, hydrophilic and porous graphene composite (GGOP) with good toughness was prepared by a one-step hydrothermal method. GGOP exhibited high and wide light absorbance (94.5% from 250 to 2200 nm wavelength), abundant porous structures (high porosity of 97.2%), low thermal conductivity (0.02 W m(-1) K-1), and low density (0.011 g cm(-3)). When GGOP was used as a solar steam generator, it delivered a water evaporation rate of 1.44 kg m(-2) h(-1) and a solar-thermal conversion efficiency of 86% under 1 kW m(-2) irradiation. Moreover, it was also confirmed that GGOP maintained a stable performance for solar steam generation even after 10 cycles. Our results demonstrate that graphene/graphene oxide composite nanosheets have a good prospect in solar steam generation.