A plasmonic interfacial evaporator for high-efficiency solar vapor generation

The increasing energy and environmental concerns have spurred enormous research interest towards developing various renewable energy and sustainable environmental solutions. Photothermal conversion for interfacial solar vapor generation is a promising, green energy technology and efficient route for desalination and purification of seawater, i.e. for those parts where freshwater shortage is a severe concern and clean energy is not available. Eco-friendly, highly efficient and low-cost interfacial evaporators are highly desirable for the practical and widespread application of this technology. In this work, we have demonstrated a novel interfacial evaporator employing Cu9S5 nanonets with heterogeneous hexagonal holes as the photothermal conversion material and a microporous poly(vinylidene fluoride) membrane (PVDFM) as the supporting material. The Cu9S5/PVDFM evaporator displays a broadband (from 250 to 2000 nm) and large (approximate to 91.7%) solar absorptance. The porous structures of Cu9S5 nanonets and PVDFM facilitate the water transportation, and the large optical absorption of Cu9S5/PVDFM converts most of the solar energy to thermal energy, producing water vapor with high efficiency. The Cu9S5/PVDFM evaporator exhibits solar vapor generation efficiencies of 80.2 +/- 0.6% and 91.5 +/- 1.1% under one-sun and four-sun irradiation, respectively, making it among the best copper sulphide-based solar evaporators reported so far. This Cu9S5/PVDFM evaporator is reusable, flexible, highly efficient, easy to prepare, easy to scale up, and controllable for tailoring, showing a promising future for interfacial solar vapor generation.