The Synthesis And Performence Research In Solar Steam Systems Of Carbonized Plants And TiO₂/Carbon Composites

With the expansion and application of solar-powered steam systems in sewage purification,power generation,and seawater desalination,the efficient generation of solar steam has attracted more and more attention.Existing studies have reported many strategies to improve the performance of solar evaporation systems,the most prominent of which is to improve the efficiency of steam generation by using absorbers based on carbon-based nanomaterials or plasmonic metal nanoparticles with excellent structures.However,factors such as high cost,complex process,and low light-to-heat conversion efficiency hinder the application of solar-driven water evaporation systems in actual water bodies.In recent research,the use of low-cost plant materials with unique native structures to prepare photothermal absorbers for solar evaporation systems has become a research focus in this field.In our work,we improved the method of carbonizing biomass materials to obtain natural sunlight absorbers,using a simple one-step hydrothermal method to synthesize controllable structure（retaining the original pore structure of the plants）and controllable composition（introducing hydrophilic groups to improve the hydrophilicity of the material）plant carbonized material.In addition,on the basis of the preparation of carbonized plant materials,the three-dimensional carbon of carbonized plant leaves,petals,fruit shells,plant stalks and other materials decorated by TiO₂（TiO₂/carbon composite）was prepared by combining the biotemplating method and the hydrothermal method for the first time.Different from the composite materials in existing research,the combination of biotemplating and hydrothermal method can make the TiO₂in the composite grow uniformly on the inner and outer surfaces of the material for playing a synergistic effect in the SSG,while its preparation process completely retains the porous structure of plant leaves.The material can promote the efficient production of solar steam and can be used for the evaporation and purification of actual water bodies.The main research conclusions are as follows:Under the simulated light intensity of 1kW/m~2,among the materials prepared,the water evaporation rate of the blade TiO₂/carbon composite material can reach up to 2.31 kgm^-2h^-1.Compared with pure water evaporation,the rate is 3.45 times higher.The water evaporation rate of petal TiO₂/carbon composite material is up to2.02 kgm^-2h^-1,which is 3.48 times that of pure water evaporation under the same conditions.The evaporation performance of TiO₂/carbon composite materials prepared with hard templates such as plant stems can also be increased by 2.48times.The prepared material has excellent water transmission performance and good light absorption performance.The application results in actual water bodies show that the prepared cassia leaf TiO₂/carbon composite material can be used to evaporate and purify pharmaceutical wastewater.The maximum productivity of the solar still with the TiO₂/carbon was 6.9L/m~2.day in outdoor conditions.After purification,the removal rate of COD in the wastewater reaches 98.8%,and the removal rate of ammonia nitrogen is 90.8%.