Solar-driven enhanced chemical adsorption and interfacial evaporation using porous graphene-based spherical composites

Solar-energy-driven water purification is a promising technology for obtaining clean water during the current global climate crisis. Solar absorbers with high light absorption capacity and efficient energy conversion are critical components of solar-driven water evaporation and purification systems. Herein, we demonstrate that porous reduced graphene oxide (rGO)-based composite spheres facilitate efficient water evaporation and effective organic pollutant adsorption from water. Most solar light (>99% for 1 mm thick composites) is absorbed by the porous rGO-based composite spheres floating on water and is subsequently converted into heat, which is efficiently transferred to water at the air-water interface. Evaporation efficiency via energy conversion by the floating sphere composites reaches ∼74%. The increase in surface temperature of water also contributes to improving the adsorption capacity of the rGO-based composite spheres for organic pollutants. Furthermore, the composites can effectively block ultraviolet radiation, preventing the chemical reaction of water pollutants into harmful components.