The Application In Environmental Purification Of That The Synergy Of Photocatalytic (Photoelectrocatalytic) And Fenton Reaction

Nowadays,environmental pollution and energy crisis have become two major issues in human social life.Hydrogen peroxide is getting more and more attention because of its various advantages,such as high safety,good stability,convenient transportation,and its use in fuel cell power generation.At present,the main method of industrially producing hydrogen peroxide is the anthraquinone oxidation method.However,this method has the disadvantages that the raw material gas is flammable and explosive,the catalyst is expensive,and the organic solvent is still required to add in the purification stage.Photocatalytic technology and photoelectrocatalytic technology are based on solar energy,with sufficient energy sources,green and pollution-free,and have gradually become new technologies for the production of hydrogen peroxide.The work of this dissertation is mainly focused on the problems of removing water pollutants and preparing clean energy hydrogen peroxide,designing new reaction processes and developing efficient semiconductor photocatalysts and photovoltaic catalysts.Combining the research results reported in the existing literature and the research foundation of this research group,it is planned to prepare g-C₃N₄-based visible light absorbing materials for converting solar energy into chemical energy or electrical energy,and further improve its efficiency of removing water pollutants and producing hydrogen peroxide.The main research contents of this paper are as follows:?1?GCN anchored with Fe used for photo-Fenton synergistic system to degrade pollutantsGCN with active sites of highly dispersed iron was prepared by a one-pot thermal polycondensation method.The XPS results show that iron is likely to coordinate with pyridine nitrogen and have a certain interaction,so that the loading of iron is very firm.The results of the activity test found that the degradation efficiency of RhB under the photo-Fenton system is much greater than the algebraic sum of the photocatalysis and the Fenton reaction,indicating that there is a synergy between the photocatalysis and the Fenton reaction.Combined with capture experiments,we conclude that this synergy is mainly manifested as:on the one hand,photo-generated electrons on the surface of g-C₃N₄ can promote the conversion of Fe³⁺to Fe²⁺in the rate-limiting step of the Fenton reaction;on the other hand,Fe³⁺reacts with photo-generated electrons to promote the separation of photogenerated carriers.?2?FeCN/FTO as photocathode for oxygen reduction to hydrogen peroxideThe catalyst obtained in the previous chapter was loaded onto the FTO by a blade coating method and used in a system for photoelectrocatalytic oxygen reduction to produce hydrogen peroxide.After optimization of the reaction conditions,the maximum yield of hydrogen peroxide was 5.62 mM·h^-1·g^-1_cas,which was 5.5 times the initial GCN.Through a series of electrochemical tests such as linear scanning voltammetry and rotating disk electrodes,we found that iron-loaded GCN is beneficial for the rapid separation of photo-generated carriers,and it is more inclined to undergo a two-electron reaction to generate the target product hydrogen peroxide.Finally,through cyclic degradation testing of pollutants and detection of iron leaching,we found that the catalyst has good stability.?3?ACN/FTO used as photocathode to produce hydrogen peroxide and used for immediate treatment of pollutantsA nitro-containing GCN was successfully prepared by nitric acid method.The presence of nitro groups was verified by XPS and infrared spectroscopy tests.The results of the activity test showed that the maximum yield of hydrogen peroxide reached60 mM·h^-1·g^-1_cas,which was 4.3 times the initial GCN.It can be seen from the test results of the rotating ring disk electrode that the selectivity of the composite material to generate H₂O₂ is as high as 90%,which is one-sixth higher than the initial GCN.Through ESR testing,we found that the introduction of a nitro group can induce the oxygen reduction reaction to form·HO₂^-,thereby improving the yield and selectivity of H₂O₂.In addition,the introduction of pollutants in the reaction system and the combination of divalent iron ions to trigger the Fenton reaction can effectively use hydrogen peroxide to treat the pollutants in a timely manner,while also avoiding the problem that the generated H₂O₂ is difficult to separate.This work embodies the advantages of photoelectrocatalytic oxygen reduction to produce hydrogen peroxide,and provides a new solution to the problem of difficult separation of hydrogen peroxide production.