| Hydrogen energy is a kind of clean energy that is completely zero-pollution because its combustion product is water.Oxygen evolution reaction is the half reaction of water splitting.Because of its slow kinetics,a high overpotential is required to make the reaction proceed smoothly.The addition of oxygen evolution catalyst can effectively reduce the reaction overpotential and save energy.Current commercial oxygen evolution catalysts are precious metal based catalysts,such as Pt/C,RuO2,IrO2,etc.The precious metal based catalysts have good catalytic activity,lower oxygen evolution overpotential and better stability.However,the price of precious metals is high,and the content of the earth is low,so it is difficult to apply it on a large scale.Therefore,it is of great practical significance to study non-precious metal-based catalyst materials that can replace noble metal-based catalysts.In this work,iron and nickel transition metal elements are the research object,using carbon ball as a template to prepare carbon spheres/iron-nickel alloy composite materials and carbon spheres/iron-nickel oxide composite materials,and then tested their oxygen evolution reaction performance.The specific research contents are as follows:（1）The carbon spheres/iron-nickel alloy composites with different mass ratios of raw materials were prepared by thermal reduction method.XRD,Raman,SEM and TEM were used to characterize the prepared materials.Thermal co-precipitation method was used to prepare carbon sphere/iron-nickel oxide composites with different mass ratio of raw materials.The XRD,SEM and TEM were used to characterize the prepared materials.（2）Electrochemical catalytic performance analysis of carbon spheres/iron-nickel alloy composite samples were tested in 1 M and 0.1 M potassium hydroxide（KOH）solutions,including linear sweep voltammetry（LSV）test and Tafel test,AC impedance（EIS）testing,stability（CP）testing.The test results show that the FeNi@10mgCS sample in 1M KOH solution has the best oxygen evolution catalytic performance.Its potential at10 mA/cm2 is 1.565 V,and it reaches 123.5 mA/cm2 when the loading voltage is 1.75 V.The lowest Tafel slope is 50.2 mV/dec,and the internal resistance is 12Ω.The stability test shows that,the internal resistance gradually decreases,and the catalytic activity gradually increases.Oxygen evolution performance of FeNi@10mgCS sample was tested in 0.1 M KOH solution.Compared with 1 M KOH solution,the catalytic performance was greatly reduced.The initial potential was increased from 1.524 V to 1.543 V,and the internal resistance was increased from 12Ωto 100Ω.The activity deteriorates and the stability deteriorates.（3）Electrochemical catalytic performance analysis of carbon spheres/iron-nickel oxide composite samples were tested in 1 M and 0.1 M potassium hydroxide（KOH）solutions,including linear sweep voltammetry（LSV）tests and Tafel Test,impedance（EIS）test,stability（CP）test.The tests show that the NiFe2O4@50mgCS sample in 1M KOH solution has the best oxygen evolution catalytic performance.Its potential at 10 mA/cm2 is1.58 V,reaching 139 mA/cm2 when the loading voltage is 1.75 V.The Tafel slope is49.8mV/dec,and the internal resistance is 10Ω.The stability test shows that,the internal resistance gradually decreases,and the catalytic activity gradually increases.Oxygen evolution performance tests of the sample in 0.1 M KOH solution showed that the NiFe2O4@50mgCS sample still showed the best catalytic activity,its potential at10mA/cm2 was 1.61 V,and the limiting current density reached 27 mA/cm2 when the loading voltage was 1.75 V;the Tafel slope value was 81.6 mV/dec and the resistance value was about 90Ω. |
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