Excellent dual-photothermal freshwater collector with high performance in large-scale evaporation

Facing the global aggravation of freshwater resource scarcity situation, it is absolutely critical to develop a high efficiency, low cost, scalable and environmental technology for increasing demand of freshwater. Herein, we present an excellent dual-photothermal freshwater collector (DPFC) that combines the properties of graphene oxide (rGO) and silver nanoparticles (Ag NPs) to form three-dimensional porous materials in a polyvinyl alcohol (PVA) gel network, where rGO/Ag plays the key role in dual-photothermal conversion. The introduction of Ag NPs into GO sheets not only restricts GO stacking but also improves the stability and dispersity of Ag NPs in rGO sheets. As a solar steam generator, the DPFC possesses great hydrophilicity, light weight, which are favorable to realize efficient energy utilization and heat localization for water collector. With high absorbance of rGO/Ag, the DPFC exhibits a high solar energy conversion efficiency of 95.67% and an evaporation rate of 3.20 kg m(-2) h(-1) under one sun (1 kW m(-2)), thus the freshwater can be generated effectively. Especially, DPFC generates freshwater to be 6.25-9.38 L m(-3) h(-1) under outside sunlight. As for 20% salt aqueous solution, DPFC completely inhibits the salt precipitation under one sun to get freshwater. Such a dual-photothermal freshwater collector provides an insight to design of novel materials for a wide range of applications, e.g., freshwater collection.

Automated summary

This article introduces an excellent dual-photothermal freshwater collector, which combines graphene oxide and silver nanoparticles to form three-dimensional porous materials in a polyvinyl alcohol gel network. It has the characteristics of high energy conversion efficiency and high evaporation rate, and can effectively generate freshwater.