Graphene Oxide Aggregate Modification And Photothermal Complex Properties Of Phase Change Materials

The light-to-heat conversion material refers to a type of material that can convert light energy into heat energy through its own light-to-heat conversion mechanism under light conditions.Mainly used in the field of solar thermal energy storage.Since the visible spectrum area accounts for about 50% of the total solar radiation energy,and the infrared spectrum area accounts for about 43%,and the energy of these two light areas is relatively high,they can also be used for power generation,sterilization,and solving water pollution.Desalination,energy shortages and other issues are increasingly prominent.The core of photothermal materials is to select suitable photothermal conversion materials.By selecting suitable photothermal materials,the photothermal conversion efficiency can be improved,and the light energy can be efficiently converted into the required heat energy.The converted solar energy usually appears in the form of sensible heat,which is manifested as a significant temperature increase.Sensible heat has a relatively low capacity and is not suitable for energy storage.At the same time,the temperature drops rapidly when solar radiation stops;considering that solar radiation is intermittent,it is necessary to combine photothermal materials with heat storage materials to sustainably use solar energy;phase change materials are proven to be converted from solar energy to thermal energy A good heat storage material.In the field of thermal energy storage,the main problems currently being solved are to improve its thermal conductivity,solve phase change leakage and improve the efficiency of light-to-heat conversion.In this regard,this thesis starts from the composite shaping,constructs a multi-layer special structure and high photothermal material as a support material,and prepares a composite shaping with high phase change enthalpy,high photothermal conversion efficiency and good thermal conductivity.Phase change energy storage materials.The specific research mainly includes the following three aspects:(1): Polyethylene glycol(PEG)is used as the organic phase transformation component.Considering that graphene oxide(GO)has a large specific surface area and abundant surface functional groups,it is easier to modify the surface functional groups.GO is cross-linked and modified by a mixed solution of Cu SO4 and thiourea.Cu2+ is cross-linked graphene oxide(GO)and thiourea is introduced to amidate the carboxyl groups on the GO surface to obtain GO-Cu SO4-thiourea material and organic The phase change component PEG was compounded in situ to prepare a PEG/GO-Cu SO4-thiourea composite shape-stable phase change material.The maximum filling amount of PEG in the composite material reaches 95%.At this time,the enthalpy of fusion of the composite material reaches 150.6 J/g,and the shape is stable when the phase transition occurs,and it will not leak.In addition,the material has good thermal conductivity and thermal energy storage function.The photothermal conversion performance is good,and its photothermal conversion and thermal energy storage efficiency can reach percent of 67.2.(2):Polyethylene glycol(PEG)is used as the organic phase transformation component,and the hyperbranched polymer polyethyleneimine(PEI)is used to assemble and reduce graphene oxide(GO)flakes at room temperature,and the assembled graphene oxide(GO))Into a three-dimensional multilayer structure.PEG is filled in the three-dimensional multilayer structure.The maximum filling amount of PEG in the composite material reaches 95%.At this time,the fusion enthalpy of the composite material reaches 150.7 J/g,and the shape is stable when the phase transition occurs.No leakage will occur.In addition,since the thermal conductivity of graphene oxide(GO)after polyethyleneimine treatment is not affected,the material has good thermal conductivity and thermal energy storage functions.The light-to-heat conversion performance is good,and its light-to-heat conversion efficiency can reach percent of 92.(3):Polyethylene glycol(PEG)is used as the organic phase transformation component.Considering that graphene oxide(GO)has a large specific surface area and abundant surface functional groups,it is easier to modify the surface functional groups.The introduction of urea-containing small molecules with-NH2,hydrothermal reduction of GO can make GO into a loose and porous layered aerogel.The target product obtained by mixing urea and GO hydrothermally is combined with PEG in situ,and the polyethylene Alcohol(PEG)is dispersed into the three-dimensional structure to obtain PEG/hydrothermal GO-urea shaped phase change material.The experimental results show that the maximum proportion of PEG filling in the composite material can reach 95%,and the melting enthalpy value of the composite material It reaches 153.6J/g,and has shape stability when phase transition occurs,and no leakage occurs.In addition,the material has good thermal conductivity and thermal energy storage function.The light-to-heat conversion performance is good,and its light-to-heat conversion efficiency reaches percent of 89.5.