Sponge-templating synthesis of sandwich-like reduced graphene oxide nanoplates with confined gold nanoparticles and their enhanced stability for solar evaporation

Solar evaporation based on plasmonic metal nanoparticles (MNPs) is emerging as a promising technology. However, the fine structure of MNPs is unstable, and both the high temperature generated by intensive light and corrosive ions in water could damage them. The performance will decline after recycling and long-time usage. To address these issues, we adopted a sponge-templating method for preparing sandwich-like nanoplates with the gold nanoparticles (Au NPs) confined in reduced graphene oxide (rGO) nanosheets. Due to the confinement effect, both the surface melting and ion diffusion were suppressed. The solar evaporator based on the sandwich-like nanoplates showed a high solar-vapor conversion efficiency of 85.2% under a high light intensity of 10 kW. After 30 times recycle of seawater desalination, the conversion efficiency scarcely decreased. These sandwich-like nanoplates with enhanced thermal and chemical stability of Au NPs are promising in the practical application of seawater desalination.