Preparation Of Fe-Co-Ni Ternary Alloy By Electrochemical Method And Its Electrocatalytic Properties

Fe-Co-Ni alloy has unique physical and chemical properties,and has been used as a functional material in electrocatalysis,hydrogen evolution materials,magnetic materials and other fields.Therefore,it is of great significance to study the preparation methods of Fe-Co-Ni alloy electrode materials and the effects on the composition,structure and morphology of the prepared electrode materials as well as the properties of the alloys.The characteristics of Fe-Co-Ni alloy prepared by electrodeposition method were studied.The factors affecting the composition,structure and morphology of Fe-Co-Ni alloy prepared by electrodeposition were investigated.The Fe-Co-Ni obtained by changing the preparation conditions was determined.The hydrogen evolution and oxygen evolution characteristics of the alloy in NaOH solution were studied.The main research contents and conclusions are as follows:?1?Research on process characteristics of electrodeposition of Fe-Co-Ni alloyThe process characteristics of electrodeposited Fe-Co-Ni alloys prepared by electrodeposition were investigated by steady state polarization method.When the single-component Fe,Co and Ni were prepared by electrodeposition,the sequence of precipitation of metals from easy to difficult was Ni,Co,and Fe.When co-deposition of Fe-Co-Ni,anomalous co-deposition occurred.The Ni that deposits most easily precipitates is more difficult to precipitate than Co and Fe during co-deposition.The precipitation potential of Fe-Co-Ni alloy is between that of single-component deposition Fe and the precipitation potential of Ni,and can be from simple salt solution.Co-deposition was formed to obtain Fe-Co-Ni alloy.With the increase of the total metal ion concentration of Fe²⁺,Co²⁺ and Ni²⁺,the increase of electrolyte pH,and the decrease of operating temperature,the overpotential of Fe²⁺,Co²⁺,and Ni²⁺ coprecipitation increased,and the precipitation rate of the alloy at the same electrode potential became slower.The total concentration of metal ions in the electrolyte is controlled,the concentration of Fe²⁺ and Co²⁺ decreases,the overpotential of the alloy decreases,the precipitation rate of the alloy becomes faster at the same electrode potential,and the change of Ni²⁺ concentration has no effect on the co-sedimentation overpotential of Fe²⁺,Co²⁺,and Ni²⁺.?2?Study on composition,structure and micromorphology of electrodeposited Fe-Co-Ni alloyFe-Co-Ni alloys were prepared by galvanostatic electrodeposition.The composition of Fe-Co-Ni alloys was determined by energy dispersive spectroscopy?EDS?.The alloy structure was characterized by X-ray diffraction?XRD?and observed by scanning electron microscope?SEM?.Alloy morphology.The effects of Fe²⁺,Co²⁺ and Ni²⁺ molar ratios,electrolyte pH,operating current density and operating temperature on the composition,structure and morphology of Fe-Co-Ni alloys were investigated.The results show that the electrodeposition process consists of a mass transfer process and an electrochemical reaction process.When the Fe-Co-Ni alloy electrodeposition is under mass transfer control,the molar ratio of the alloy to the metal ion molar ratio in the solution is similar.When the electrodeposition process is in reaction control,the difference between the alloy composition and the molar ratio of metal ions in the solution is the greatest;when the electrodeposition process is under mixed control,the molar ratio of the alloy composition to the metal ion in the solution is between the two extreme cases.As the total concentration of metal ions in the electrolyte decreases or the operating current density increases,the electrodeposition process of the Fe-Co-Ni alloy tends to be controlled by mass transfer.The closer the composition ratio of the alloy to the composition of the metal ions in the electrolyte,the closer it becomes.When the total concentration of metal ions in the electrolyte increases or the operating current density decreases,the electrodepositing process of Fe-Co-Ni alloy tends to control the reaction,and the difference between the composition ratio of the alloy and the molar ratio of metal ions in the electrolyte increases.The content of Ni in the alloy composition is lower than the content of Ni in the electrolyte,and the content of Fe and Co is higher than that of the electrolyte.In the reaction control process,the molar ratio of Fe,Co,and Ni in the electrolyte is adjusted to 1:1,and if the concentration of the other component is increased,the composition of the alloy obtained by electrodeposition also increases,but the amount increases.There is no linear relationship between the amount of this component added in the electrolyte and the increase in the operating current density or temperature,the Fe content in the electrodeposited alloy increases,the Co content decreases,and the Ni content remains unchanged.Changing the composition of the electrolyte can regulate the surface of the alloy to be granular or bulk morphology,but it has little effect on the structure of the prepared alloy;the smaller the operating current density,the denser the alloy,and the larger the operating current density,the more alloy particles change.Large,and the alloy structure transforms from the face-centered cubic structure to the body-centered cubic structure;as the operating temperature becomes higher,the surface of the alloy film changes from flat and dense to porous particles,and as the temperature increases,the particles become larger,and the crystal structure increases from face to face.Cubic structure to body-centered cubic structure transformation.?3?Hydrogen evolution and oxygen evolution characteristics of Fe-Co-Ni alloy prepared in NaOH solutionThe hydrogen evolution and oxygen evolution characteristics of the prepared Fe-Co-Ni alloy in 4.0 mol·L-1 NaOH solution were investigated by steady state polarization method.The results show that the hydrogen evolution and oxygen evolution activity of Fe-Co-Ni alloy in 4.0mol·L-1 NaOH solution will increase relatively simple to Fe,Co,and Ni.When Fe²⁺,Co²⁺ and Ni²⁺ contents in electrolyte increase,the hydrogen evolution and oxygen overpotential of Fe-Co-Ni alloy increase,but the hydrogen evolution and oxygen evolution activity of the alloy prepared by increasing the concentration of Co²⁺ in the electrolyte increase obvious.As the temperature increases and the operating current density increases,the hydrogen evolution and oxygen evolution activity of the Fe-Co-Ni alloy decrease.