Reduced graphene oxide/carbon nitride composite sponge for interfacial solar water evaporation and wastewater treatment.

Interfacial solar-driven steam generation has been proposed as a cost-effective green sustainable technology to alleviate the freshwater crisis. However, the desire to produce clean water from water sources containing organic contaminants is still remains a challenge due to the limitations of the traditional wastewater treatment methods. Here, we constructed a g-CN-based composite sponge solar steam generator (rGCPP) by a simple hydrothermal reaction. Benefiting from its low cost and easy preparation, this evaporator can be expected to be a promising candidate for the alleviation of water shortages and water pollution in practical applications. By combination of the solar steam generation and the photocatalysis into the rGCPP-based interfacial solar-driven steam generation system, the resulted rGCPP-based solar steam generator performs outstanding solar absorption of 90.8%, which achieves high evaporation rate of 1.875 kg m h and solar-to-vapor efficiency of 81.07% under 1 sun irradiation. Meanwhile, organic pollutants in the water source can be completely removed by photocatalytic degradation and the degradation rates were measured to be 99.20% for methylene blue and 91.07% for rhodamine B, respectively. Consequently, the as-prepared composite sponge has promising applications in generating clean water and alleviating water pollution.