Preparation Of Ferromolybdate And Its Application In Lithium-oxygen Battery And PhotoFenton System

Energy shortage and water ecological and environmental pollution problems are important issues facing the development of human society at present.With the rapid development of global economy and continuous population growth,the demand for energy and resources is increasing,which also tends to cause energy crisis and environmental problems.Modern society depends on fossil energy,and the extraction and use of fossil energy has brought great negative impact on the water ecology.To solve these problems,research and development of efficient multifunctional catalysts can improve the efficiency and selectivity of chemical reactions,reduce the reaction temperature and energy consumption,which can achieve efficient and sustainable production methods and reduce the waste of resources and environmental pollution.In the context of carbon neutrality and carbon peaking,the research and application of high-efficiency catalysts are of great significance to achieve low-carbon economy and green development.It can play an important role in chemical industry,energy industry,environmental protection and other fields to promote sustainable development and ecological civilization.Meanwhile,the research and application of new material catalysts can also bring economic and social benefits,promote scientific and technological innovation and industrial upgrading,and promote sustainable development and green transformation of the economy.Therefore,the research and development of efficient multifunctional catalysts are of great significance to solve the problems of energy and water ecology and environmental pollution.In this paper,using a combination of hydrothermal and calcination methods to prepare iron molybdate nanosheets for application in the photo Fenton degradation of methyl orange（MO）,we dissected the catalytic performance and mechanism of iron molybdate activated peroxodisulfate（PDS）under simulated daylight irradiation,and investigated the proposed mechanism of superoxide radical and sulfate radical guided degradation.Iron molybdate nanoparticles were prepared using a combination of electrostatic spinning and calcination and applied to the cathode catalyst of lithium oxygen batteries（LOBs）to investigate the cycling stability and multiplier performance of the batteries and explore the possibility of LOBs operating in an air environment.The main elements are as follows:（1）Study on the catalytic performance and mechanism of MO degradation by iron molybdate Photo Fenton system.A combination of hydrothermal and calcination methods was used to prepare iron molybdate nanosheet catalysts,and the physicochemical properties such as microscopic morphology and crystal structure of iron molybdate were analyzed by various characterization methods such as SEM,EDS,TEM,XRD,Raman and FT-IR.The UV-Vis/PDS/FeMoO Photo Fenton catalytic system was constructed by selecting MO as the target pollutant,and the effects of different catalytic（photocatalytic,PDS activation,Photo Fenton）systems,catalyst dosage,target pollutant concentration,PDS dosage concentration and initial p H value of the solution on the catalytic degradation were investigated.The results showed that under the optimal conditions（room temperature of 25℃,PDS dosing concentration of 2 m M,pollutant concentration of 20 mg/L,catalyst dosing amount of 2 g/L,p H=3 and light source of 1000 W xenon lamp）,the degradation rate of MO in the Photo Fenton degradation system was 100%within90 min.After five times of repeated utilization,the degradation rate of MO decreased from 100%to 91.7%.The radical capture test was performed to identify the main reactive oxygen species in the Photo Fenton catalytic reaction,and it was found that the main reactive oxygen species in the Photo Fenton degradation of MO wer·O₂^-,h⁺,¹O₂,SO₄^·-and·OH（in order of contribution）,and the Photo Fenton degradation of MO was regulated by both radical and non-radical pathways,and the catalytic performance of ferromolybdate was mainly related to the Fe³⁺/Fe²⁺redox cycle.Iron molybdate is the active site for both photocatalysis and PDS activation in the photo Fenton system,while the presence of oxygen vacancies also enhances the efficiency of the catalytic reaction.（2）Catalytic performance and mechanism study of ferric molybdate in LOBs.A combination of electrostatic spinning and calcination was used to prepare iron molybdate nanoparticles as positive catalysts for LOBs,and their physicochemical properties such as microscopic morphology and structural features were analyzed by various characterization means such as SEM,TEM,XRD,XPS and Raman.Under the conditions of no solid electrolyte,redox additives,selective oxygen permeable film and lithium anode protection,three atmospheres of oxygen,air and semi-enclosed air were selected for the cell cycle stability and multiplicity performance tests,and 500,137 and289 cycles could be achieved at a current density of 500 m A g^-1 for oxygen,air and semi-enclosed air conditions,respectively,and at a half-sealed A long cycle life of more than 1800 h was obtained at a current density of 200 m A g^-1 for the half-sealed air condition.Through battery charge/discharge tests and density flooding theory calculations,it was concluded that the stable polyhedral framework consisting of Fe-O octahedra and Mo-O tetrahedra in the ferromolybdate structure provides efficient catalytic activity and stable surface conditions during the cycling process.The reaction kinetics and electrocatalytic mechanism of the iron molybdate cathode catalyst under air and pure oxygen conditions were compared,and the main discharge products in the air environment were determined to be amorphous Li_2-xO₂ and Li₂CO₃,and the effect of corrosion of the lithium anode on the cycling stability of LOBs was investigated.In addition,the instability of Li O₂ and Li₂O₂ on Fevacancies promotes the formation of amorphous discharge products and accelerates the kinetic process of catalytic reactions,revealing the catalytic mechanism of LOBs in air environment and providing a scheme for finding suitable catalysts in air electrodes.