Preparation And Photo-thermal Conversion Property Of Spherical Carbon Materials By Ice Template Method

In recent decades,the continued deterioration of global environment has caused people's demand for clean energy to rise year by year.The efficient use of solar energy can solve the energy crisis and environmental problems aroused by a series of human activities.Research and development of new functional materials is the key to achieving this goal.Nanostructured carbon materials naturally have unique physical and chemical properties and have thus become research hotspots in solar related fields.This thesis mainly realizes reasonable construction and functionalization through the preparation of spherical carbon materials and the design of morphological structure and systematically studies their photothermal conversion performance.(1)we use a general spray-assisted ice templating method combined with carbonization to prepare spherical carbon material with water-soluble polymers as precursor.The different morphologies and structures of the carbon materials prepared under different carbonization temperature conditions,different freezing temperature conditions,and different raw material concentration conditions were investigated.The experimental results show that the prepared spherical carbon material maintain a good assembled spherical structure with increasing carbonization temperature,and when the temperature reached 2800?,the structure mainly changes to a dense spherical structure.As the freezing temperature decreases,the carbon material changes from a bulk material to a thin sheet structure,and finally to an extremely thin 'translucent' sheet structure.By adjusting the raw material concentration,we have realized the structural transformation of multidimensional carbon materials from nanofibers to nanosheet assemblies and further to dense spherical carbon materials.In addition,we explored the effect of surface tension and precursor concentration on the morphological transformation and performed a systematic analysis of internal mechanism.The spray-induced increase of interfacial tension resulted in a significant decrease in the freezing point and the growth of the formed polymer embryos was inhibited by the quenching of liquid nitrogen.Thus,the templating effect of ice crystals directly affected the final structure of the product.With the increase of concentration,the increase of the density of the nucleus of polymer crystal embryos leads to the formation of different morphological structures under the action of ice template.(2)We combine the prepared spherical carbon material with polyurethane to prepare a solar absorbing material capable of efficiently generating steam.Spherical carbon material/polyurethane has features of highly developed pore structure,good hydrophilicity,and extremely low thermal conductivity.Its solar light absorption is as high as 97%in the spectral range of 250-2500 nm.Under the irradiation of 0.5 kw m-2,the water evaporation rate of spherical carbon material/polyurethane can reach 0.72 kg m-2 h-1,and the efficiency of solar steam generation can reach 81.7%.In addition,we have designed outdoor solar evaporation device in actual scenarios and tested its evaporation performance.The collection rate of evaporated condensate is approximately 0.1945 kg m-2 h-1.