Study On Preraration And Photothermal Conversion Performance Of Magnéli Phase Ti₄O₇

Photothermal conversion technology is considered to be the most direct and efficient solar energy utilization technology.The use of photothermal conversion properties of materials for the desalination of seawater can efficiently solve the problem of water shortages caused by population growth and environmental pollution.The core of the photothermal conversion technology is the photothermal conversion material,and the inorganic semiconductor material is difficult to get mass production and has stability problems when used as a photothermal conversion material.This paper presents the preparation and photothermal conversion properties of Magnéli phase Ti₄O₇,which has been widely used in electric and energy storage.First,micro Ti₄O₇ with high stability was prepared by common chemical methods and then submicron Ti₄O₇ was obtained by a simple ball milling method.Scanning calorimetry（DSC）,X-ray diffractometry（XRD）,scanning electron microscopy（SEM）,and UV-Vis-IR spectrophotometers were used to characterize the samples.A simulated light model was established to study the morphology,phase,light absorption capacity,and photothermal conversion performance of the material.The effects of particle size and light absorption capacity on the photothermal conversion performance were analyzed.The ability of the material to be used for desalination was analyzed with simulated evaporation water experiments.In addition,micro Ti₄O₇ was combined with rare earth ions to explore the influence of rare earth ions on the light absorption capability of micro Ti₄O₇.Micro Ti₄O₇ was prepared by leaching,solid-liquid separation and electrochemical reduction.It was found that the material has far less bandgap than TiO₂ and can absorb about 89.5%of full-spectrum sunlight,which is superior to some common carbon materials（Graphite,flake graphite,expanded graphite）and TiO₂.Besides,it has a photothermal conversion efficiency of about 79.5%,and its solar water vapor generation efficiency is increased by 3.89 times compared to the efficiency that micro Ti₄O₇ was absent in the solar evaporation water experiment.Submicron Ti₄O₇ was obtained by ball milling.It was found that the bandgap width and crystalline of the prepared submicron Ti₄O₇ is slightly larger than that of the micro Ti₄O₇,and the visible light absorption capacity is decreased,and about 89.3%of full-spectrum sunlight can be absorbed.The submicron Ti₄O₇ has a photothermal conversion efficiency of about 73.7%.Its solar water vapor generation efficiency is 2.15times higher than that without the submicron Ti₄O₇.The results show that the particle size of the Ti₄O₇ decrease,the light absorption capacity and photothermal conversion capacity of the Ti₄O₇ also reduce,indicating that the particle size reduction by ball milling may leads to the material’s poor light absorption and photothermal conversion capability.Ti₄O₇-NaBiF:Yb³⁺/Er³⁺composites were prepared by co-precipitation method.It is found that the doping of rare earth elements is beneficial to micro Ti₄O₇ to improve the light absorption ability.The composites are potential photothermal conversion materials.