Synthesis Of Fe₃Si Aerogels And Their Applications On Photothermal Water Evaporation And Catalysis

In the 21st century,environmental pollution and energy shortage are two major problems in human society.The development and utilization of renewable clean energy is extremely urgent to solve the two problems.As a clean renewable energy source,solar energy has attracted widespread attention and is considered to be one of the most promising alternatives to fossil energy.Solar energy has many forms of utilization,converting solar energy into heat energy has the highest light-to-energy conversion rate.However,the energy density of natural sunlight is dilute,so that the temperature of the converted heat energy is low and the taste of heat energy is poor.Therefore,it is great challenge to convert the sunlight from the natural environment into high-grade heat energy.Solar thermal utilization is dependent on the use of photothermal materials to convert light energy as heat.At present,the research of photothermal materials is mainly focuses on metals,carbon materials and other black light absorbing materials to fully adsorb sunlight.However,at present,the photothermal materials,e.g.,carbon materials,metal nanoparticles and Fe₃O₄ have good thermal conductivity,which makes the large heat dissipation,resulting in low temperature,which seriously restricts the application of light converted heat energy in industry.Therefore,it is of great significance to study the preparation of photothermal materials with both full sunlight absorption capacity and low thermal conductivity.Herein,we innovatively introduced the aerogel structure into the photothermal materials,and successfully prepared the Fe₃Si aerogel photothermal material.As a black intermetallic compound,it exhibits full sunlight absorption in the whole solar spectrum.At the same time,the special mesoporous structure effectively reduces the thermal conductivity of the material,making it not only 100%light absorption efficiency but also has an excellent heat storage capacity.Under standard sunlight,the photothermal conversion temperature of Fe₃Si aerogel can reach 102°C,which is significantly higher than traditional photothermal materials.By encapsulating the Fe₃Si aerogel material into a photothermal vacuum tube,further reduced the heat radiation and heat conduction loss,the photothermal converted temperature reaches to as high as 250°C.The main research contents and conclusions of our Fe₃Si aerogel for photothermal water evaporation and photothermal catalysis are as follows:1.The Fe₃Si aerogel was coated on the upper surface of the melamine foam for photothermal seawater desalination.Under the simulated sunlight(1 kW·m^-2)irradiation,the interface temperature between the material and the water body is above 50°C,and the evaporation water efficiency is 2.08 kg·m^-2·h^-1.2.The material is hydrophobized for the study of corrosive water evaporation.The water evaporation performances of Fe₃Si aerogel has been tested in 0.5 M H₂SO₄ and 1 M NaOH solution,resulting in stable 1.35 and 1.21 kg·m^-2·h^-1 water evaporation rates,respectively,under a sunlight irradiation(1.16 kW·m^-2).3.The Fe₃Si aerogel is encapsulated in a photothermal vacuum tube for the study of catalytic oxidation of CO.The prepared Co₃O₄ diamond nanorods were loaded on the inner wall of the Fe₃Si photothermal vacuum tube by immersion method,and the CO conversion efficiency could reach to 95%using this system just under simulated sunlight of 0.5 kW·m^-2,realizing the natural sunlight-driven CO catalysis.