Electrocatalytic Degradation Of Organic Pollutants By N-Doped Carbon Materials And Its Application In Self-Powered Degradation System Constructed By 3D Printing Technology

The rapid development of industry brings human welfare,but at the same time,a large number of organic contaminants discharged into the water body causes serious environmental pollution.Researchers have been exploring and improving efficient degradation of organic pollutants,and along with the continuous development of wastewater treatment technology,advanced oxidation processes(AOPs)have attracted much attention because a large number of hydroxyl radical(·OH)can be produced in these processes,which can effectively remove organic contaminants.However,most of the AOPs have some shortcomings,such as complex treatment processes,difficult operations,and unsatisfactory degradation effects,and so on.Electro-Fenton(EF)technology has become a new,efficient,and clean advanced electrochemical oxidation process with broad application prospects.However,it is necessary to further improve the degradation ability to organic wastewater treatment by improving the whole performance of electrode materials.Besides,the EF reaction needs a continuous power supply,which leads to excessive energy consumption.These factors undoubtedly restrict the application of EF in industrialization.In the process of EF reaction,the cathode material is required to have the characteristics that include good adsorption and aggregation ability to organic pollutants,the electrode material can fully contact with O₂ and the mass transfer efficiency is high,high-efficiency catalysis of O₂ and generating H₂O₂.Therefore,the choice of cathode material is very important for the entire EF reaction.The catalytic electrodes made of carbon materials have the advantages of non-toxicity,strong conductivity,corrosion resistance,good chemical stability,and high catalytic activity.Carbon materials are herein expected to be the best solution to replace Pt and other precious metal electrodes.Moreover,carbon materials have wide sources,large reserves,low prices,and simple preparation process,which are very suitable for mass promotion and application.Besides,the triboelectric nanogenerator(TENG)technology can convert the mechanical energy in the surrounding environment into electrical energy,which can provide the electrical energy source for driving the EF reaction instead of traditional power sources.However,traditional manufacturing methods limit the free design and manufacture of TENG devices,and new manufacturing technologies are urgently needed to solve this problem.Based on this,this topic focuses on exploring the preparation of carbon materials with high catalytic activity(melamine sponge and biomass as precursors)for cathode EF reaction to oxidize and degrade organic pollution.At the same time,3D printing technology is introduced to explore the construction of personalized TENG energy harvesting devices with high performance,low cost,and rapid prototyping.Finally,TENG-based self-powered cathode EF organic pollution degradation systems are built.And this paper carries out the following research work:(1)Melamine sponge is chosen as precursor to prepare N-doped carbon materials which are used as the cathode electrocatalytic material of EF reaction.We innovatively introduce digital 3D printing technology to build a series of high-performance,personalized,and low-cost TENGs,and then deeply combined them with the cathode EF reaction to build self-powered electrochemical degradation system which can achieve 98%degradation efficiency in 100 min for the difficult-to-degrade azo organic contaminant of 4-dimethylaminoazobenzene(DAB,10 mg L^-1).Besides,we also successfully constructed self-powered electrochemical oxidation polymerization system and self-powered synthetic ammonia system,which provides innovative ideas for the application of the self-powered electrochemical field.(2)A series of N-doped carbon materials are prepared by using artemisia argyi as the precursor, MgO and ZnCl₂ as pore-forming agents.The optimal N-doped carbon has a large specific surface area(1302m~2 g^-1)and is used in cathode EF reaction for degradation of methylene blue(MB)organic pollutants system.At the same time,3D printing technology is used to realize the free processing and production of flexible material TPE,and to fabricate a flexible wave-shaped TENG,which can provide 6.1 W m^-2 power supply when the load is 1 M?,which can provide stable and continuous power supply for the EF reaction.MB solution can be degraded in 58 min with a degradation rate of 98.10%.Besides,it is found that the content of oxygen-containing functional groups in the carbon catalyst is positively correlated with the corresponding degradation efficiency through the analysis of the structure-activity relationship.(3)We innovatively use Chinese parasol tree bark as precursor,NH₄HCO₃ and ZnCl₂ as pore-forming agents to prepare a series of N-doped biomass carbon materials with tunable catalytic activity.NH₄HCO₃ is used as a dynamic gas template and can decompose into NH₃,CO₂,and H₂O molecules under pyrolysis process to bring about numerous pores,favorably enriched the pore structures for the catalyst.The optimal carbon material has large specific surface area,high N and O doping content,and good hydrophilicity.The catalytic performance and unique structure of the carbon material are explored by a series of characterization methods.The TENG can provide 5.07 W·m^-2 of electrical energy at a load of 1 M?.The self-powered cathode EF degradation system was constructed to degrade orange IV and crystal violet,and the degradation rates of 96.0%and 95.4%were achieved within 1 h,respectively.The structure-activity relationship analysis shows that the content of-C-O-C functional groups in carbon catalytic materials is positively correlated with the corresponding degradation efficiencies.This study guides the preparation of N-doped porous carbon materials with tunable catalytic activity.To sum up,this research realizes the deep integration of cathode EF oxidation technology,N-doped carbon material preparation technology,digital 3D printing technology,TENG based energy harvesting technology and apply them to self-powered electrochemical catalytic degradation of organic pollutants,which simultaneously solve the shortcomings of cathode materials and energy supply of EF reaction.The research provides innovative ideas for the effective degradation of organic pollutants.At the same time,it also provides technical guidance for the popularization and application of self-powered electrochemical systems.