The Design Of Copper/Carbon Composite Photothermal Film For Interfacial Solar Steam Generation

The shortage of fresh water resources has become one of the serious problems threatening the future survival and development of human beings,and extracting fresh water from the abundant sea water is an important way to solve this problem.At present,the widely used desalination technologies mainly include multi-stage flash evaporation,reverse osmosis and electrodialysis,etc.However,these technologies have the problems of high energy consumption and secondary pollution.Interfacial solar steam generation(ISSG)is regarded as a green,efficient and low-cost desalination technology for seawater desalination by utilizing clean energy such as solar energy.Interfacial evaporator has a decisive influence on ISSG overall desalting performance.In this thesis,through the design,synthesis and modification of structure of copper/carbon matrix composite film,the interfacial evaporator with high light thermal conversion performance was prepared.The main contents are as follows:1.Porous graphene oxide(P-GO)membranes have been prepared by a simple etching method.The light absorption of P-GO is more than 85%in the range of 200-2500 nm,which is much higher than that of pure GO membrane(～75%).This is attributed to the porous structure which enhances the internal reflection of incoming light between the GO layers.The evaporation test results show that under the irradiation of 1 kW m-2,the evaporation rate and the evaporation efficiency of P-GO reach 1.77 kg m-2 h1 and 88.26%,respectively.In addition,the deionization performance of P-GO membrane was tested by using natural lake water.Meanwhile,using methylene blue(MB)solution as the target solution,results show that 99.13%MB can be removed by P-GO membrane.2.Flake and flocculent copper oxide(CuO)photothermal films were prepared by solvothermal and vacuum filtration,respectively.The morphology,structure and light absorption properties of CuO photothermal films with different CuO microstructures and contents were characterized.The results showed that the light absorption rate of CuO films with different microstructures was more than 80%in the UV-Vis region.With the increase of CuO content,the surface temperature of the two CuO photothermal films under the irradiation of 1 kW m-2 also increases.The evaporation test results show that the maximum evaporation rates of flake and flocculant photothermal CuO films under 1 kW m-2 irradiation are 1.71 kg m-2 h-1 and 1.66 kgm-2 h-1,respectively,and the evaporation efficiencies are 85.80%and 83.29%,respectively.In addition,simulated seawater and methyl orange(MO)solution were used to demonstrate the excellent ions and organic pollutants removal properties of CuO photothermal film with different microstructures.3.A novel two-dimensional GO/CuO photothermal film was prepared by a simple ultrasonic method.The prepared GO/CuO photothermal film showed a sandwich nanostructure,and the CuO nanoparticles were confined in the GO layer.This benefits to enlarge the GO layer spacing,which makes GO/CuO films has a longer optical path.On the other hand,CuO promotes the absorption of incident light throughout the visible range.Besides,the water contact angle of GO/CuO film is 57.4°,which is much lower than that of pure GO film(74.8°),indicating that GO/CuO film has a higher water transport rate.The results show that the maximum absorption of GO/CuO film is 83%and that of pure GO film is 74%.Under the irradiation of 1 kW m-2,the evaporation rate of GO/CuO film is the highest,reaching to 1.71 kg m-2 h-1 with the efficiency of 99.2%.After 20 cycles of desalting,the evaporation rate is still 1.60 kg m-2 h-1.Further,GO/CuO film was used to treat organic pollutants,and the removal rate reached more than 90%.4.Carbon coated copper nanoparticles/carbon cloth Janus photothermal film(Cu@C/CC)was prepared by solvothermal and thermal reduction methods.SEM images showed that the carbon coated Cu@C retained the urchin-like structure,which was favorable for light capture and oxidation resistance.The light absorption results show that Cu@C/CC exhibits 92%in the wavelength range of 200-2500 nm,much higher than the 80%of pure CC films.Meanwhile,the contact angle test showed that Cu@C/CC has a typical Janus structure.The evaporation test results show that the evaporation rate and efficiency of Cu@C/CC reach 2.31 kg m-2 h-1 and 91%,respectively.After 10 cycles,the evaporation rate remained at 2.17 kg m-2 h-1.In addition,using simulated seawater as the target solution,the excellent deionization performance of Cu@C/CC was verified,and the removal rates of MO and MB were 99.6%and 98.6%,respectively.