Contrlled Synthesis And Electrocatalytic Performance Of Oxygen Evolution Of KMF₃（M=Co,Ni） And K₃FeF₆ Nanomaterials

With the rapidly development of society,energy consumption,environmental pollution,and other issues become more and more highlights.Fossil energy,as the main energy supply of non-renewable energy,cannot meet the needs of social and economic development.At the same time,the use of fossil fuels is accompanied by serious environmental pollution problems.Therefore,the find of new energy instead of the non-renewable energy is one of the research focuses currently.Among the many advanced technologies,Hydrogen Production electrolyzed water in alkaline medium is a broad application prospect.And the oxygen evolution reaction plays an important part which during the energy conversion of electrolytic water.Electrolyzed water comprising of anode oxygen evolution reaction（OER）and cathodic hydrogen evolution reaction（HER）two half reaction.Compared with HER,OER is more difficult.The reaction involves four-electron transfer and the formation of covalent bond（O-O）bond.During the reaction,the rate is slow and requires a higher overpotential.In order to improve the efficiency of OER,among the many new electrocatalysts have been developed.Many iron-based（Fe,Co,Ni）catalysts due to potential electrocatalytic properties,such as good stability,abundant reserves and low cost,which have become the most promising oxygen evolution catalyst.At present,there are few studies on the electrocatalysis of iron-based（Fe,Co,Ni）transition metal fluorides,but they meet the two basic principles of electrocatalyst design.Therefore,this article aims to develop iron-based（Fe,Co,Ni）transition metal fluoride catalysts with low cost,high output and excellent OER performance.The major research content of this article is:（1）A series of cubic phase KCoF₃ NCs electrocatalysts were synthesized in the OA/HA system by solvothermal method in this conditions,such as the amount of KF and KOH,reaction time and reaction temperature.Study their effects on the crystal phase,morphology and OER performance of KCoF₃nanocrystals（NCs）.The research results show that the KCoF₃ NCs prepared at KF concentration of 3 mmol,KOH concentration of 8 mmol,reaction time of 12h and reaction temperature of 180℃ have the best OER performance,at the current density of 10 mA cm^-2,the overpotential value is 270 mV and the Tafel slope of 77.68 mV dec^-1.（2）In oleic acid（OA）and n-hexanol（HA）solvent system,a series of cubic phase KNiF₃ NCs electrocatalysts were synthesized by solvothermal method under the following conditions,including the amount of KF and KOH,reaction time and reaction temperature.Study their effects on the crystal phase,morphology and OER performance of KNiF₃ NCs.The research results show that the KNiF₃ NCs prepared at KF concentration of 2 mmol,KOH concentration of 2 mmol,reaction time of 48 h and reaction temperature of200℃ have the best OER performance,at the current density of 10 mA cm^-2,the overpotential value is 370 mV and the Tafel slope of 17.52 mV dec^-1.（3）In OA/HA solvent system a series of cubic phase K₃FeF₆ NCs electrocatalysts were synthesized by solvothermal method,by adjust the amount of KF and KOH,reaction time and reaction temperature.Study their effects on the crystal phase,morphology and OER performance of K₃FeF₆ NCs.The research results show that the K₃FeF₆ NCs prepared at KF concentration of 5mmol,KOH concentration of 2 mmol,reaction time of 12 h and reaction temperature of 180℃ have the best OER performance,at the current density of10 mA cm^-2,the overpotential value is 290 mV and the Tafel slope of 99.21 mV dec^-1.