Inspired by the natural water cycle process, the use of solar-driven water evaporation to obtain clean fresh water has attracted the attention of researchers.In the natural evaporation conditions, the utilization of the sun is lower, the actual evaporation is slower.The researchers try to have Good light absorption and photothermal conversion ability of the photothermal film material applied to the solar-driven evaporation system to improve the evaporation efficiency.Previous studies have shown that the controllable microstructure of the rough surface can effectively reduce the diffuse reflectance of light to achieve However, the construction of surface microstructure is more complicated and often requires special equipment or means to assist the completion, thus increasing the difficulty and cost of membrane material preparation.
Accordingly, the membrane separation and catalysis team led by Jiang Heqing, a researcher at Qingdao Institute of Bioenergy and Process Research, Chinese Academy of Sciences proposed that the composite strategy of nano-materials with different dimensions should be used to control the microstructure on the surface of the photothermal film so as to enhance the light trapping efficiency, To obtain the ideal photothermal evaporation efficiency.The researchers through the two-dimensional graphene and one-dimensional carbon nanotubes complexed to achieve a single component of the orderly structure of the disturbance, increasing the surface roughness of the photothermal film. The optimization of the surface micro-structure can reduce the diffuse reflection in the solar spectrum to below 4.7% and the surface temperature of the film in the light to reach 77 ° C. The disorderly accumulation increases the porosity in the membrane and is beneficial to the water molecules in the membrane Compared with the natural evaporation, based on the nano-composite photothermal film evaporation process efficiency increased by 190%, the utilization of solar energy more than 80% .In practical applications, the study proposed nanocomposite photothermal Membranes not only maintain stable performance in simulated water samples containing acids, alkalis and organic pollutants, but also accelerate water evaporation in seawater with different salt contents, showing excellent Fresh water production capacity and the ease of preparation of such light-heat composite membranes can be built on different porous substrates.The results of this research are expected to promote the use of solar-powered clean freshwater preparation for efficient, green and sustainable seawater desalination and Fresh water protection under emergency conditions.
Relevant research results were published in Journal of Materials Chemistry A. The research was supported by the National Natural Science Foundation of China, Shandong Provincial Natural Science Foundation and Qingdao Municipal People's Livelihood Science and Technology Project.
Figure 1. Schematic diagram of nanocomposite photothermal film preparation based on two-dimensional graphene and one-dimensional carbon nanotubes
Figure 2. On-line Photo-thermal Evaporation Test System (a) and Photo-thermal Film Material Solar-Energizing Evaporation Performance Test
