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Due to the abundance and easy availability of solar energy resources, solar-driven water evaporation provides a sustainable way to obtain clean water from wastewater and seawater. However, achieving a high evaporation rate with excellent light absorption remains a critical challenge in the structural regulation of evaporators. Herein, inspired by the natural transpiration process in plants (blue spruce), we designed a three-dimensional (3D) cone-shaped solar steam generator based on vertical polypyrrole nanowires-coated fabric (VPPyNWs-fabric). The microstructure design of polypyrrole (PPy) increases the solar energy absorption of the incident light through multiple reflections between the VPPyNWs, while the macrostructure design of the 3D evaporator possesses an enlarged surface area for energy harvesting, wide path for water supply, and open structure for vapor diffusion. As a proof of concept, the as-obtained 3D VPPyNWs-fabric-based solar steam generator demonstrates a fast water evaporation rate of 2.32 kg m–2 h–1 with high solar absorption of 97% and solar-to-vapor conversion efficiency of 98.56% at 1 kW m–2 energy density. In addition, the solar steam generator can be steadily applied in various water conditions, e.g., seawater, dye wastewater, and acidic and alkaline wastewater. This high-performance evaporator via 3D macro- and microstructure design offers a new avenue for better utilization of solar energy.
He et al. (Thu,) studied this question.