Tailoring core@shell structure of Cu2−xSe@PDAs for synergistic solar-driven water evaporation

Solar-driven water evaporation, a promising method to obtain freshwater resources, has drawn intensive attention recent years due to the abundance of solar energy and scarcity of clean water. Here, we introduce a robust strategy to obtain a series of polydopamine-modified Cu2−xSe nano-composites (Cu2−xSe@PDAs) with core@shell structure, which has strong absorption in solar spectrum and outstanding photothermal conversion efficiency for freshwater production. Temperature of the obtained Cu2−xSe@PDA30 aqueous solution could increase from 19.4 to 70.6 °C in 5 min under the irradiation of 980-nm NIR laser with the power density of 0.002 kW·cm−2. Under 0.5 simulated sunlight irradiation, water evaporation rates were as high as 3.36 kg·m−2·h−1 when using the Cu2−xSe@PDA30 for desalination, indicating excellent evaporation efficiency under weak light. Moreover, the obtained Cu2−xSe@PDA30 can also apply to wastewater purification and the evaporation rate could reach 2.71 kg·m−2·h−1 under an irradiation of simulated sunlight with intensity of 1 kW·m−2. These results provided new insight into solar desalination and wastewater treatment using nanoscale semiconductor materials.