Preparation Of Silver-carrying Carbon Nanotubes Polyvinyl Alcohol Hydrogels And Their Water Evaporation Properties

Carbon nanotubes（CNTs）are widely used in the fields of catalysis,antibacterial and sensing because of their unique hollow tubular structure and excellent physicochemical properties.In recent years,the rapid development of CNTs technology has opened a new way for the efficient assembly of metal particles in the pore of carbon nanotubes,which has greatly enhanced the functionality of carbon nanotubes in the pore-limited system.The assembly of silver nanoparticles into the interior of the official cavity of carbon nanotubes can lead to photothermal materials with very excellent light absorption and photothermal conversion efficiency.In this paper,with the concept of safe,efficient and green preparation,silver nanoparticles are prepared by chemical reduction using green reagents as reducing agents,and the large diameter multi-walled carbon nanotubes（MWCNTs）are used as carriers to open the ports by mixed acid oxidation and assemble the silver nanoparticles into the official cavities of carbon nanotubes by capillary action to obtain a photothermal material with high optical absorption performance.The prepared Ag@MWCNTs photothermal material was successfully compounded into polyvinyl alcohol hydrogel with excellent photothermal effect by choosing polyvinyl alcohol（PVA）as the carrier of photothermal material,and the evaporation efficiency could reach 95.28%and the evaporation rate reached 1.92 kg·m^-2h^-1.The specific research of this paper The contents are as follows:（1）A simple,efficient and green chemical reduction method was used to prepare silver nanoparticles with regular shape and uniform particle size distribution,and they were assembled inside MWCNTs by in situ reduction to form a new photothermal material Ag@MWCNTs,and their morphology and structure were characterized by TEM,XRD and other means.The results showed that the silver nanoparticles were successfully assembled into the lumen of MWCNTs,while the particle size of silver nanoparticles was between 30 nm with uniform distribution.（2）The Ag@MWCNTs/PVA photothermal gels were prepared by compounding the prepared Ag@MWCNTs photothermal materials into polyvinyl alcohol hydrogels by physical cross-linking cycle freeze-thaw method.The morphology and structure of the composite hydrogel were characterized by SEM and TGA,and the water evaporation test was also performed on this photothermal hydrogel.The results showed that the Ag@MWCNTs/PVA hydrogel had excellent light absorption performance,in which the evaporation rate of the hydrogel at a solid content of 1.5 mg/ml was 1.92 kg·m^-2h^-1,and the evaporation efficiency was 95.28%.Meanwhile,the evaporator designed and prepared with Ag@MWCNTs/PVA hydrogel has great potential for water evaporation and desalination applications.