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Metal-free Carbon Catalysts For Oxygen Reduction Reactions Towards The Selective Generation Of Hydrogen Peroxide

Posted on:2022-05-27Degree:MasterType:Thesis
Country:ChinaCandidate:Y ZhouFull Text:PDF
GTID:2491306764993539Subject:Inorganic Chemical Industry
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Hydrogen peroxide(H2O2)is a versatile and environmentally friendly oxidant,widely used in bleaching,disinfection,wastewater treatment,chemical synthesis,semiconductor cleaning and waste gas treatment.At present,the large-scale industrial production of H2O2 is the anthraquinone method,which can produce high-concentration H2O2 and then transport it to various places where it is needed.In recent years,with the development of renewable energy technology and the demand for a new method of decentralized on-site synthesis of hydrogen peroxide(H2O2),the use of electricity generated by clean energy such as solar and wind energy for electrochemical two-electron oxygen reduction(2e-ORR).The synthesis of H2O2 is considered to be a simple,low energy consumption and environmentally friendly method.The design and synthesis of electrocatalysts with high ORR activity and high H2O2 selectivity are key factors.Metal free carbon catalysts(MFCCS)has become a research feature due to its low price and easy availability,high specific surface area,high conductivity,and easy surface modification.This dissertation takes XC-72 carbon powder as the research object,through surface oxidation,organic-inorganic interface engineering and other methods to modify,studied the influence of the concentration and type of oxygen-containing groups of XC-72 carbon powder on the performance of electrocatalytic synthesis of H2O2.In addition,the paper also studied the auxiliary effect of photothermal effect on the electrocatalytic synthesis of H2O2,as follows:1)The XC-72 carbon powder is processed by two methods:400℃muffle furnace baking and 80℃oven baking.The photoelectron spectroscopy shows-COOH;-C-O-C group is helpful for oxygen reduction to produce H2O2,the selectivity and yield have increased significantly.Raman spectroscopy reveals that the increase in the ratio of ID:IG contributes to the formation of defects and improves the selectivity of H2O2.During the electrolysis of 0.1M KOH solution,the XC-72 carbon powder calcined at 80°C exhibits excellent oxygen reduction current.This result provides a new research idea for the construction of oxygen-containing groups on the surface of carbon powder by different oxidation methods.Compared with a single traditional oxidation method,the mild oxidation method has the characteristics of simple reaction and energy saving.2)Taking advantage of the characteristics of self-polymerization of dopamine on the surface of XC-72,selecting dopamine hydrochloride solution and polymerization time,constructing a certain thickness of polydopamine coating on the surface of XC-72,through transmission electron microscopy,photoelectron spectroscopy,and soft X-ray absorption.The material was characterized by a variety of test methods such as spectroscopy,and the effect of the XC-72@polydopamine catalyst on the yield and selectivity of the electrocatalytic synthesis of H2O2 in a neutral medium was studied.XC-72 carbon material tends to infinitely small current under neutral conditions,showing the characteristics of being wrapped with polydopamine.Combined with relevant literature,a reasonable analysis of possible reaction mechanisms has been carried out.3)Because carbon material is a commonly used photothermal material,it is often used in applications such as photothermal evaporation of water.This chapter uses the characteristics of XC-72 carbon powder to respond to photocurrent,photothermal imaging,electrochemical impedance,and electrochemical activity.Area measurement,real-time ampere curve and other test methods,studied the effect of external light source on the yield and selectivity of electrocatalytic synthesis of H2O2,which provides a practical example for the development of photothermal auxiliary technology in the application of electrocatalysis.In summary,it is feasible to apply different control methods to optimize and improve the H2O2production of carbon material XC-72 in the electrocatalytic oxygen reduction process.Combining various characterization methods to explore the relationship between performance and structure,to explore the internal catalytic mechanism,and to study The field of electrocatalytic synthesis of H2O2has theoretical and practical significance.
Keywords/Search Tags:electrocatalyst, oxygen reduction process, carbon-based materials, hydrogen peroxide
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