RGOs-AgNPs/PVA composite sponges for efficient solar saltwater evaporation

Abstract

With an increasing demand for seawater desalination, fabricating photothermal materials with low cost, high photothermal conversion efficiency, and excellent mechanical stability is necessary but remains challenging. In this work, reduced graphene oxide nanosheets (RGOs) and silver nanoparticles (AgNPs) doped polyvinyl alcohol (PVA) sponges (RGOs-AgNPs/PVA) are fabricated by the mechanical foaming and impregnation reduction method, which combine the flexible porous structure of PVA sponges with the photothermal properties of RGOs-AgNPs. The incorporation of RGOs-AgNPs enhances the surficial hydrophobicity and reduces the accumulation of water on the surface, and the photothermal synergistic effect of RGOs-AgNPs enhances the water evaporation rate. The results showed that the evaporation rate of RGOs-AgNPs/PVA was 2.09 kg m−2 h−1 and the photothermal conversion efficiency was 94.2 % under standard sunlight intensity of 1 sun (1.0 kW m−2). Furthermore, the long-term stability and effective desalination capability of the RGOs-AgNPs/PVA solar evaporation device offer a potential opportunity for massive seawater desalination. Therefore, this work shows the prospect of combining flexible porous sponges with photothermal materials for practical solar evaporation.