Design And Application Of Multifunctional Micro-Nano Structure Broadb And Absorber

Recently,the problem of global energy shortage has become increasingly prominent.Solar absorbers that directly convert solar energy into heat provide a solution for sustainable energy development.New application scenarios are promoting the development of solar absorbers from single to multifunctional.Therefore,high-performance solar absorbers need to be developed urgently based on new materials,structures,and functions.At present,the micro-nano structure absorber with broadband absorption has made remarkable progress in solar energy utilization.However,it also faces the following problems:the synthesis and manufacturing processes of the existing absorption devices are complex,and how to construct a broadband absorber with a simpler structure,lower cost,and large-area manufacturing under the same performance is a problem that needs to be solved;the mechanical properties or structural stability of micro-nano-structured devices are poor,and how to ensure that the absorber still has excellent light absorption and mechanical stability under repeated stress or load impacts,which is another problem faced by the absorber;the existing absorber has a single function,and how to develop a multifunctional broadband absorption device based on photothermal application is also one of the challenges it faces.To solve these problems,this dissertation takes advantage of the high dielectric loss properties of the material itself,using a spraying or drip-coating process,to construct a multifunctional micro-nano-structured broadband absorber with a simple and robust structure.Therefore,starting from the capture,absorption,and photothermal conversion of photon energy by high-loss nanoparticles absorbers,this dissertation studies the photothermal performance of the absorber and its new functions and applications.The main contents are as follows:(1)The light absorption and photothermal performance of the absorber with high dielectric loss nanoparticles(C,Cr,W,TiN,Ti C)were studied by using finite element method multiphysics modeling.By analyzing different absorber structures(square,rhombus,and chaos structures),it is concluded that the structure shape has no significant effect on the light absorption performance in high-loss nanoparticle absorbers.When the volume ratio of nanoparticles to the absorber is less than 20%,the absorber can obtain more than 90%light absorption.In addition,the effect of particle size and volume ratio on performance is the same.To get high absorption,make sure the volume ratio is as small as possible.Since the structural shape of the absorber has little effect on the performance,the volume ratio can be inferred from the obtained average absorption efficiency when the particle size is constant.By introducing thermal mass transfer,the photothermal performance of the absorber was analyzed,and the following conclusions were drawn:(a)the layer thickness and the thermal conductivity of the dielectric had the most significant influence on the temperature rise;(b)the volume ratio has little effect on the thermal localization effect;(c)the substrate needs to avoid using the high thermal conductivity materials(such as Al₂O₃)to improve the photothermal performance.(2)A plasmonic TiN absorber with super-flexibility and superhydrophobicity was fabricated.By coupling TiN nanoparticles with polydimethylsiloxane solution,a plasmonic TiN absorber with excellent light absorption,photothermal effect,superhydrophobicity,robust flexibility,impact resistance,wear resistance,and self-healing ability was constructed.By irradiating the absorber with a laser power density of1 W·cm^-2,the surface temperature of the absorber can be rapidly increased from room temperature to 130? within 90s,verifying the photothermal effect of the absorber.By fabricating different thicknesses samples,the influence of the absorber layer thickness on temperature rise was analyzed,providing theoretical and data support for the photothermal application of absorbers.Photothermal superhydrophobic absorbers with different applications were fabricated by using different substrates.The mechanical structure stability and self-healing ability of the absorber were verified by 500 times bending-twisting cycle experiments,1 m·s^-1 high-speed water impact,250 g sand abrasion,tape peeling,and plasma damage experiments.Finally,a multifunctional application of the designed absorber was carried out.Through self-cleaning at room temperature and low temperature,long-term acid-alkali solution immersion,irregular coverage,anti-icing,deicing,and defrosting experiments,verified that the absorber has practical application value.Thus,the proposed TiN absorber provides a feasible solution for multifunctional applications of superhydrophobic surface engineering.(3)A FBC/TiN absorber with photothermal superhydrophobicity was fabricated.By coupling TiN nanoparticles with biochar(BC)to construct a hierarchical micro-nano porous structure,a FBC/TiN absorber with high photothermal effect and superhydrophobicity was obtained.By adding TiN nanoparticles to control the hydrophobicity of the BC material,a superhydrophobic surface with a contact angle of up to 156°and a roll-off angle of less than 5°was obtained.The absorber layer thickness was controlled by BC,and a thermal insulating layer(TIL)was inserted between the absorber layer and the substrate,and synergized with the photothermal effect of plasmonic TiN to achieve a surface temperature of 63.3? under a standard sunlight illumination even if the ambient temperature is below zero.The photothermal performance was tested and analyzed through light-to-thermal tests,theoretical models,and kinetic engineering models.The excellent mechanical stability of the absorber was verified by sand abrasion,water impact,bending,and tape peeling tests.Through the ultra-low temperature(<-20?)anti-icing,defrosting,and deicing experiments,the application of the absorber was verified.Finally,a FBC/TiN absorber with an area of 900cm² was fabricated,confirming its practical application potential.This method is very simple(drip coating),and can be easily combined with various solid surfaces and allows for the rapid melting of the interfacial ice layer through the photothermal effect,thereby exploiting the hydrophobic or gravitational properties to remove the overlying ice layer.In brief,FBC/TiN-based superhydrophobic photothermal absorbers will open up possibilities for realizing anti-icing/deicing applications from laboratory to large-scale industry.