The use of sunlight to drive water evaporation to obtain clean drinking water is expected as an emergency means for use in shipwrecks or in the wild. In contrast to natural evaporation processes and traditional membrane separation technologies, photothermal membranes with good photothermal conversion capabilities will be used. Applied to the sunlight-driven water evaporation system, the evaporation efficiency can be effectively improved. The membrane separation and catalysis research group led by Jiang Heqing, a researcher at the Qingdao Institute of Bioenergy and Processes, Chinese Academy of Sciences, used a composite strategy of different nano-carbon materials to apply 2D photothermal The microstructure of the membrane surface is regulated to significantly improve the water evaporation efficiency (J. Mater. Chem. A, 2018, 6, 963-971). On this basis, the team further conducted a study on hollow cone-shaped photothermal membranes. With its unique three-dimensional structure, higher photothermal water evaporation efficiency is obtained by improving the mass transfer and heat transfer performance of the photothermal film system (J. Mater. Chem. A, 2018, 6, 9874-9881).
Inspired by the collection of acoustic auricle structure, and drawing on the structure of the solar cooker, the membrane separation and catalytic research group Wang Yuchao and Jiang Heqing designed a 3D hollow cone photothermal film with macroscopic dimensions, and its photothermal conversion efficiency exceeded 93%, exceeding The limit value of common 2D planar membrane water evaporation rate. The actual seawater test in Jiaozhou Bay shows that the 3D hollow cone photothermal film not only shows good stability, but also its evaporation efficiency is 3.5 times that of natural evaporation. The medium salt will be chromatographed on the cone roll and will not cover the entire photothermal film. This will not only help the enrichment and recovery of the salt, but also maintain the stability of the photothermal performance. Detailed studies show that the 3D hollow cone photothermal Membrane ultra-high photothermal evaporation performance is mainly achieved in three aspects: (1) The specific geometric shape can limit the light inside the cone reel, and realize the photothermal reel to sunlight by multi-step reflection of light. Efficient absorption, average absorbance over 99%; (2) 3D hollow cone reel does not require additional insulation to reduce heat loss into the water, nor does it need to use other materials for water conduction, but by changing Reel in The height of the medium, regulates the contact area with water, reduces heat loss, and achieves ideal evaporation interface confinement heating; (3) The 3D photothermal cone structure is designed such that the actual evaporation area is different from the irradiation area of sunlight. Significantly increased the actual evaporation area. This work provides an experimental basis for the development and design of 3D photothermal film, and is expected to promote the rapid development of solar light driving desalination technology.
The above research work was supported by the National Natural Science Foundation of China, the Natural Science Foundation of Shandong Province and the Qingdao Minsheng Science and Technology Project. The relevant research results were published as a cover article in the Journal of Materials Chemistry A (2018, 6, 9874-9881).
Figure 1. Schematic diagram of the preparation of polypyrrole 3D hollow cone photothermal film
Figure 2. Comparison of diffuse reflectance performance of 3D hollow cone and 2D planar film samples (a) and absorbance comparison (b), schematic diagram of multi-step reflection process (c)
Figure 3. Research results were selected as cover article highlights
