Application Of Nanomaterials In Daytime Radiative Cooling Systems And Fuel Cells

Since the advent of nanomaterials,it has always been the focus of researchers all over the world and widely used in many fields such as medical treatment,energy,catalysis and environmental protection.Compared with conventional powder materials,the development of nanomaterials will have a profound impact on scientific research and social progress due to its novel nano-effects.Therefore,it is of great significance to improve the preparation methods and research the microstructure and properties of nanomaterials.In this paper,cordierite materials,one-dimensional La_0.6Sr_0.4Co_0.2Fe_0.8O_3-?(LSCF)and BaZr_0.8Y_0.2O_3-?(BZY)nanofibers were prepared by different methods,and their properties and applications were studied respectively.The main research contents are as follows:1.Nano-sized cordierite materials were prepared by sol-gel method,and its microstructure,heat dissipation and spectral absorption characteristics of cordierite were characterized in detail.Studies manifested that cordierite was an ideal daytime radiation cooling material due to its effective reflection solar radiation in visible wavelengths and high emissivity of infrared wavelengths.In the heat dissipation experiment,the metal plate covered with cordierite had a faster heat dissipation rate and a lower surface temperature,which also confirmed its excellent heat dissipation performance under daytime conditions.2.La_0.6Sr_0.4Co_0.2Fe_0.8O_3-?as a double-doped perovskite material,was commonly used for cathode material in medium and low temperature solid oxide fuel cells.The LSCF nanofibers were prepared by electrospinning and exhibited obvious semiconductor characteristics.The positive and negative magnetoresistance transition temperatures ranged from 240 to 260 K due to the competition between the effect of wave function shrinkage and weak localization.Magnetic research discussed ferromagnetism and the creation of spin-glass states.This work indicated that LSCF nanofibers had different electron conduction behaviors at different temperatures and magnetic fields,which has important significance for the design of solid oxide fuel cells based on LSCF cathode.3.The cathode materials with nanofiber structures have excellent gas permeability,faster charge transfer rate and longer three-phase boundary,which can improve stability and electrochemical performance greatly of fuel cells.LSCF and BZY nanofiber composite cathode materials were prepared by electrospinning.Compared with conventional powder cathode,the peak power density with LSCF and BZY composite nanofiber cathode was 1105 m W cm^-2,which was increased by 40%,and the polarization resistance was 0.041?cm²in 700°C.This study provides more approaches for the preparation of high quality electrode materials for solid oxide fuel cells.