Two Birds One Stone: Facile and Controllable Synthesis of the Ag Quantum Dots/Reduced Graphene Oxide Composite with Significantly Improved Solar Evaporation Efficiency and Bactericidal Performance

Interfacial solar evaporation (ISE) is an environmentally friendly and promising water treatment strategy. However, the bactericidal performance of an ISE system during the evaporation process is usually ignored, which may result in potential water safety hazards. In this study, a facile method is presented for the controllable synthesis of Ag quantum dots (QDs)/rGO to simultaneously achieve efficient solar evaporation and evaporated water disinfection. The size of the Ag nanoparticles (NPs) rather than the loading amount is the factor that considerably affects the solar evaporation efficiency and the bactericidal performance. Under 1 sun of irradiation (1 kW·m2), the evaporation rate and solar evaporation efficiency of Ag QDs/rGO are as high as 2.11 kg·m2·h–1 and 94.0%, respectively. Based on E. coli and S. aureus, the bactericidal activity of Ag QDs/rGO in the evaporation process is qualitatively and quantitatively characterized; no bacteria could be detected in the evaporated water. Furthermore, various water samples, including acidic water, alkaline water, dye water, and seawater, are selected to verify the solar evaporation performance of Ag QDs/rGO. When considering complex water samples, the as-prepared material maintains a high evaporation efficiency and an excellent purification effect, indicating attractive potential for various practical applications.