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. A dual-photothermal freshwater collector (DPFC) that combines the properties of reduced graphene oxide (rGO) with silver nanoparticles (Ag NPs) to form three-dimensional porous materials in a polyvinyl alcohol (PVA) gel network, achieves an excellent effect. • A novel dual-phothermal freshwater collectoe (DPFC). • The dual-photothermal conversion of rGO/Ag for the evaporation efficiency in freshwater generation. • Cooperation of micro-channel and nano-capillary porous for high-efficiently freshwater generation and collection.