Preparation And Interfacial Evaporation Performance Of Carbon-based Micro-nano Structured Photothermal Materials

Solar-driven interfacial water evaporation holds great prospect in seawater desalination and wastewater remediation.Solar-driven interfacial water evaporation applies photothermal materials to absorb sun light and converts it into heat which is used to evaporate water.Therefore,photothermal materials are the key for solar evaporators with high evaporation rate.In this thesis,solar-driven interfacial water evaporators with micro-nanostructures were constructed based on carbon materials.The main contents are as follow.（1）Photothermal materials were prepared through surface drilling and carbonization process,with potato as raw materials.The microstructures and chemical composition of the carbonized potato were characterized and the influences of surface pore structure on the optical absorption,photothermal conversion and solar water evaporation properties were investigated.The results showed that the porous-structured carbonized potato mainly contained amorphous carbon and exhibited the optical absorption of 86%.Surface drilling effectively improved the photothermal conversion and subsequently the solar evaporation properties of the carbonized potato.The evaporation rate was determined to be 1.44 kg·m^-2·h^-1 under one-sun irradiation(1k W·m^-2),corresponding to an evaporation efficiency of 90.71%.The carbonized potato is applicable to the remediation of organic dyes wastewater and heavy metal ions containing solutions.（2）Carbonized sugarcane was prepared by loading antimony doped tin oxide（ATO）followed by a carbonization process.The chemical composition and microstructures of the carbonized sugarcane were characterized and the optical absorption,photothermal conversion and solar water evaporation rate for the carbonized sugarcane were studied.The results indicated that optical absorption of 99% was achieved owning to the synergistic effect of carbonized sugarcane and ATO particles.The plasmon resonance of ATO particles provided localized hot spots on the surface and inside the carbonized sugarcane,which enhanced the photothermal conversion efficiency.Under one-sun irradiation(1 k W·m^-2),the evaporation rate was determined to be 1.43 kg·m^-2·h^-1,corresponding to an evaporation efficiency of 89.94%.The carbonized sugarcane holds great prospect in the remediation of organic dyes wastewater and heavy metal ions containing solutions,as well as in seawater desalination.（3）Porous ATO-C photothermal materials were prepared by freeze casting/carbonization process with carboxymethyl cellulose and ATO powder as raw materials.Broad band and high absorption of sunlight was realized due to the complementary effect of the carbonized cellulose（strong absorption of visible light）and ATO（strong absorption of near-infrared light）.The pore size and porosity were tuned by changing the freeze casting temperature.The impacts of the pore size and porosity on water evaporation were investigated and the related mechanism was revealed.The heat absorption of water in the channel leads to the reduction of evaporation rate and evaporation efficiency.On the premise of efficient water transport,reducing the porosity is beneficial to the enhancement of evaporation rate and solar evaporation efficiency.The best ATO-C photothermal material can absorb more than 98% of sunlight and deliver an evaporation rate of 1.44 kg·m^-2·h^-1 under one-sun irradiation,corresponding to an evaporation efficiency of 90.4%.