Preparation And Oxygen Evolution Performance Of Nickel-iron-based Catalytic Electrodes

The application of hydrogen energy is becoming more and more extensive,and the electrolysis of water to produce hydrogen has become an ideal way to obtain hydrogen energy.However,the electrolysis of water is limited by the anode half-reaction of oxygen evolution,which leads to a slow process.Therefore,the development and preparation of anode oxygen evolution catalysts has important practical significance.At present,the preparation of anode catalysts mainly focuses on two aspects:on the one hand,catalytic electrodes with different structures and properties are obtained through preparation methods;on the other hand,precious metals and non-precious metals are selected from the element system.In this paper,non-precious metals nickel and iron were used to prepare sintered and as-cast electrodes with high oxygen evolution activity and stable performance through powder metallurgy and casting,respectively,four atomic ratios of Ni-Fe-3-1,Ni-Fe-1-1,Ni-Fe-1-2 and Ni-Fe-1-3 series alloys were prepared.In addition,in order to further optimize the performance of the catalytic electrodes,the surface of the above electrodes was roughened by acidic roughening.The phase structure,microscopic morphology and element distribution of the electrodes were characterized by X-ray diffraction,scanning electron microscope and energy spectrometer.The electrochemical performance of the catalytic electrodes was tested by linear sweep voltammetry,electrochemical impedance spectroscopy,cyclic voltammetry,cyclic voltammetry aging and chronopotentiometry.The result shows:Under the test conditions that the surface of the sintered electrodes is smooth and planar,the overpotential for oxygen evolution of the Ni-Fe-1-2 electrode at a current density of 10m A·cm^-2is only 338.8m V.At the same time,the oxygen evolution performance of the electrode after cyclic voltammetry aging is further improved,and the oxygen evolution overpotential at10m A·cm^-2 is reduced to 308m V.The microstructure of the sintered electrodes after acidic roughening presents a porous morphology,the electrochemically active surface area is increased by nearly 30 times,providing a large number of reactive sites,and the porous structure on the surface after acidic roughening provides multiple levels for gas overflow,which improves the electrode oxygen evolution reaction rate.Under the test conditions that the surface of the as-cast electrodes is smooth and planar,the Ni-Fe-1-1 electrode has better performance than other alloys.When the current density is10m A·cm^-2,the oxygen evolution overpotential of Ni-Fe-1-1 electrode is only 330m V.The active surface area of the as-cast electrode after acidic roughening has increased by nearly 6 times.The overpotential for oxygen evolution of the Ni-Fe-1-1 electrode at a current density of 10m A·cm^-2is only 259m V.The oxygen evolution performance is significantly improved than before the electrode surface modification.