Synthesis And Separation Properties Investigations Of Carbon Nanotubes-Based Flexible Film

Since the discovery of Fullerene,low-dimensional carbon nanomaterials have attracted extensive interest.Subsequently,with the discovery of carbon nanotubes(CNT)and graphene,a large family of carbon nanomaterials and various carbon-based macroscopic assemblies are found gradually.Among them,CNT-based macroscopic assemblies,such as one-dimensional CNT fibers,two-dimensional CNT films and three-dimensional CNT gels,have made great progresses in the fields of transparent conductive films,sensors,touch screens,energy storage and so on.CNT film is a two-dimensional film assembled from CNT.CNT films grown by chemical vapor deposition(CVD)not only exhibit excellent electrical properties but also very high mechanical strength,promising its application as ideal flexible supporting materials.The studies of carbon nanotube-based composite films have made a great deal of research in the fields of catalysis,sensing,and energy storage.However,the researches on the separation properties of CNT films have not been fully explored.Thus the application of CNT films as separation films is limited and deserves more investigations.The shortage of fresh water resources is a huge challenge fecing the world at present-Water desalination technologies are regarded as the only way to solve the shortage of fresh water resources without destroying the ecological environment.Among which,solar thermal desalination technology using solar energy has attracted much attention in recent years.Photothermal materials that could absorb light and transform the adsorbed light to heat have been widely applied in the solar thermal desalination to improve the evaporation efficiency.Especially,great progresses have been achieved in heat localization for solar steam generation by photothermal materials.Carbon-based photothermal materials with high solar radiation absorption and easy functionalization promise their applications as high-performance photothermal materials for solar thermal desalination.In this paper,we constructed a series of two-dimensional CNT-based flexible films with different nanostructures by combining photothermal materials with CVD-grown CNT films.The CNT films were used as the supporting materials owning to its high mechanical strength,superior stability and easy functionalization.The thermal properties and separation properties of these CNT-based flexible films were studied and their applications in the solar thermal desalination system were comprehensively explored.The main contents are as follows:(1)An ultrathin two-dimensional porous film based on molybdenum disulfide(MoS2)nanosheets and CNT films was prepared by a hydrothermal method.The structure and compositions of as-prepared CNT-MoS2 films were systematically characterized.The ultrathin flexible characteristic,self-floating capability and thermal conductivity were explored respectively.The optical behaviors and the photothermal properties of the CNT-MoS2 composite films were investigated.The ultrathinCNT-MoS2 films reached a high evaporation efficiency of 91.5%under 5 kW m-2 solar irradiation as solar thermal desalination membranes.(2)A large-area flexible bilayer Janus film by assembling the gold rods(AuNRs)onto the CNT film was fabricated through a vacuum filtration method.The bilayer structure of CNT/AuNRs composite film was fully investigated.The flexibility and mechanical property of the large-area CNT/AuNRs composite film are explored.Subsequently,the spectrum absorption capabilities and photothermal properties were investigated in this work.In solar water desalination systems,the CNT/AuNRs composite film achieved high evaporation efficiency of 94%and excellent reusable stability.