Preparation And Properties Of COF/Carbon Nanocomposite Electrochromic Materials Based On Anthraquinone Units

The large-scale use of glass curtain walls in modern high-rise buildings has caused problems such as large energy loss and insufficient lighting.Electrochromic technology can realize energy-saving dimming,so it has gradually attracted people's attention.Different types of electrochromic materials have their own limitations.The main problem of conductive polymer electrochromic materials is poor stability.Covalent organic framework(COFs)materials,as a new type of framework material with a similar conductive polymer structure,have the advantages of large specific surface area,adjustable pore size,and high stability.We use them as active materials to develop applications in the field of electrochromism.In this paper,we use 2,6-diaminoanthraquinone(DAAQ) and1,3,5-triformylphloroglucinol(TFP)as raw materials to synthesize COFs by Schiff base reaction.At the same time,in view of the insufficient conductivity of COFs,we respectively composited them with carbon nanotubes or graphene oxide,and successfully prepared composite electrochromic materials with interfacial covalent bond connections.Further explore the influence of carbon nanomaterials(graphene oxide,carbon nanotubes)on the properties of COF materials,as well as the mutual synergy between the two materials.Specific methods such as SEM,TEM,Raman,XRD,FTIR,TGA,and nitrogen adsorption and desorption were used to characterize the material's micro-morphology,crystallinity,thermal stability,specific surface area and pore size;and through CV,UV,impedance testing and the kinetic testing methods explored the electrochemical and electrochromic properties of the materials.The specific results are as follows:We successfully prepared DAAQ-TFP COF material,and the best experimental synthesis conditions were 90?,dropwise addition(2 drops/min),and solvothermal reaction for 4 h.Subsequently,the CNT-COF composite electrochromic materials were prepared by the solvothermal method.The results showed that the composite materials have more excellent thermal stability and electrochemical activity.Among them,1%CNT-COF has the best performance,and the contrast is increased by 17.4% compared with the pure system.The contrast of the film of 1%CNT-COF is still 114.5% after 1800 s of cyclic testing.We used the same method to prepare GO-COF composite electrochromic material.With the addition of F-GO,the contrast and CV enveloping area of the composite material both increase first and then decrease.The test results show that the performance of 2%GO-COF is the best.Compared with pure COFs material,the contrast has increased by 41%.The contrast of the film material after the cyclic test for 1800 s is still the original 108.9%,which is far greater than the stability of the pure system.