Nano Construction Of Carbon-Nitrogen Based Materials And Their Application In Organic Pollutants Treatment

With the rapid development of human economy,the increasingly serious environmental pollution has become a huge challenge for people.Peroxymonosulfate（PMS）based Fenton process has become a hot research topic because PMS could produce more active species than traditional Fenton process to improve the pollutants degradation performance.In addition,it is a novel and green strategy to treat pollutants as a potential resource for the production of value-added fine chemicals.The carbon-nitrogen based two-dimensional materials are new type of two-dimensional carbon material with excellent properties.Because of their high specific surface area and structural diversity,carbon-nitrogen based two-dimensional materials have been widely explored by researchers in the catalytic field.（1）Based on the microwave technology,a dicyandiamide and cobalt nitrate rapid carbonization method was developed to prepare carbon aerogel material,in which cobalt oxide species were uniformly dispersed.The rapid heating process gave cobalt oxide species the characteristics of multivalent states and oxygen vacancies introduction.Major active species SO₄^·-and ¹O₂were generated in the Co@C₃A/PMS system with the assistance of multivalent cobalt and oxygen vacancies.In addition,the N doping further promoted the electron transfer efficiency of the catalytic materials.The electrochemical experimental results showed that Co@C₃A had better electronic conductivity.Therefore,Co@C₃A/PMS system could achieve 100%removal of tetracycline hydrochloride（TC）in 10 minutes.The quenching experiment showed that SO₄^·-and ¹O₂played a major role in the degradation reaction,and the free radical capture experiment proved the existence of·OH,SO₄^·-,O₂^·-and ¹O₂in the degradation system.（2）Although based on Co@C₃A Catalyst activated PMS has achieved good results in the degradation of organic pollutants.In order to further avoid the use of metal oxides and PMS,we have explored greener and environmentally friendly methods for the treatment of environmental pollutants.Novel,green and efficient strategy was developed for environmental pollutant chlorophenols and carbon dioxide transformation to carboxylic acids containing fine chemicals over carbon nitride（C₃N₄）nanotubes based photocatalysis.C₃N₄nanotubes structure with hydrothermal treatment method provided the increased active sites,enhanced light absorption capacity and improved charge transfer efficiency.C₃N₄nanotubes further modified by hydroxyl groups in situ grafting and halogen ions were prepared by simple hydrothermal treatment strategy with ammonium salt and potassium iodide.Owing to the photogenerated holes capture improvement,hydroxyl groups in situ grafting policy obviously enhanced the chlorophenols and CO₂transformation.Moreover,the chlorophenols carboxylation efficiency was further promoted with the synergistic effect of hydroxyl groups assisted photogenerated holes capture and halogen ions induced surface polarization.Furthermore,control experiments,free radical capture and quantitative experiments were carried out to study the possible mechanism of chlorophenol carboxylation reaction.The mechanism study not only proved the reaction intermediate in the process of carbon dioxide reductive carboxylation,but also confirmed that hydroxyl group grafting and halogen ion modification could synergistically affect the formation of·OH in the catalytic system,thus improving the reaction selectivity.In conclusion,we have successfully synthesized stable and efficient Co₃O₄/CoO loaded carbon aerogel composites and carbon nitride nanotubes.The as-synthesized catalytic materials showed excellent catalytic performance in both advanced oxidation pollutant degradation and novel photocatalytic pollutant resource and CO₂reutilization reaction.In addition,the possible mechanism of the catalytic reaction was also studied by combining various quenching experiments and free radical capture experiments.