Hollow Carbon Fiber Decorated by Nano Structure Surface for High-Efficiency Water Steam Generation

Utilization of carbon materials for harvesting solar energy is a green, feasible, sustainable, and promising way to manufacture freshwater from sewage and seawater. However, sunlight absorption efficiency, light to thermal conversion efficiency, and expensive cost are still limitations for large-scale solar steam generation. Here, a solar steam evaporator which is fabricated by carbonized willow catkins films and activated by different metal chlorides under nitrogen at 800 °C is demonstrated. Under the light irradiation intensity of one sun (1000 W m −2 ), water evaporation rate of the prepared evaporator is up to ≈2.17 kg m −2 h −1 , and the surface temperatures reach up to 50 and 91.7 °C under water-saturated and dry situations, respectively, indicating good steam generation ability and heat localization performance of the fabricated evaporator. The SEM, BET, DSC, and ICP-MS results show that such a high water evaporation rate of the prepared carbon materials is due to the typical tubular micro-structure, which decreases water enthalpy of evaporation and the water evaporation in the form of molecular clusters. This method of carbonized and activated willow catkins films provides a sustainable way for efficiently harvesting solar energy to produce fresh water from seawater and sewage.