Modulation Of Covalent Organic Framework And Application Of Photocatalytic Degradation Of Organic Pollutants

Covalent organic frameworks（COFs）are a new type of porous material consisting of organic units bonded into a periodically ordered,high specific surface area,π-conjugated structure,structural designability and strong chemical stability,which are widely used in various scientific fields such as adsorption and separation,catalysis,CO₂reduction,solar cells and fuel cells,and are of great scientific value and practical use in life.These selected organic units are connected into two-dimensional（2D）or three-dimensional（3D）topologies by covalent bonds such as imine bonds,boron esters,hydrazones,zines or ketoamines.COFs formed from different molecular building blocks have tunable band gaps,a high-specific surface area with more active sites,and a long-lasting thermal and chemical stability,are both remarkable,and therefore COFs are often used as photocatalysts for catalysis.The use of COFs as catalysts for the catalytic conversion of pollutants using solar energy has generated much research and discussion in order to address the environmental pollutants brought about by industrialisation,which is not only energy efficient but also environmentally friendly.The simple synthesis of high quality and high yield COFs has been the primary problem in the conventional design of COFs materials.Based on this the synthesis of COFs materials by solvothermal method is designed and the yield is regulated by the addition of emulsifier and the photocatalytic performance is improved by non-precious metal deposition.In this paper,the morphology and size of TFPB-TAPT synthesized from1,3,5-tris（p-formylphenyl）benzene（TFPB）and 2,4,6-tris（4-aminophenyl）-1,3,5-triazine（TAPT）were firstly modulated by the addition of the emulsifier Triton X-100,which improved the bulk synthesis of TFPB At the same time,the photocatalytic degradation efficiency of COF-Triton X-100 was investigated by the addition of emulsifier Triton X-100,which was 3.8 times higher than that of COF,significantly improving the photocatalytic efficiency.By adding emulsifier,the problem of low yield of COF synthesis was solved,providing a new synthetic route for industrial production of COF.To address the issue of the exorbitant cost of fabricating organic components for COFs,we chose the lower cost terephthalaldehyde with 2,4,6-triaminopyrimidine and melamine to synthesize covalent organic frameworks of PT and PM,respectively.By testing different mass numbers of raw materials,PT with the best specific surface area was selected as the base material,and units of Fe（OH）₂,Ni（OH）₂and Zn（OH）₂of non-precious metals were doped in PT by deposition,and the doping success was determined by XPS,EDS maping and ICP.The improvement in photocatalytic activity was then judged by the degradation efficiency of methylene blue（MB）,where Zn（OH）₂loaded PT-Zn（OH）₂could degrade 98%of 10 ppm methylene blue at 40 min,much higher than the base material PT which could only degrade42%at 40 min.by UV-vis,XPS-VB,EIS,PL,i-t,etc.electrochemical tests,it was found that the deposition of Zn（OH）₂enhanced the electrochemical properties of PT-Zn（OH）₂and therefore the photocatalytic effect was substantially improved.This work explores the photocatalytic effect of Zn,a non-precious metal material,and provides a photocatalyst that can be mass-produced,cheaply available and highly efficient.