Preparation And Electrochemical Properties Of Nickel Selenium Compounds

In recent years,with the rise and development of the field of total electrolytic water,the excellent functions of alloys and the continuous expansion of the demand for new energy industries,it is particularly important to find a cheap substitute for noble metal electrolytic water catalytic hydrogen evolution and oxygen evolution materials.Transition metal phosphides and transition metal selenides have also received extensive attention due to their excellent catalytic performance,which makes transition metal compounds become the focus of research on related catalytic materials.The nickel-selenium alloy material is cheap and easy to obtain,and the cost of electrochemical modification is low.The experimental process does not produce toxic components,so it is of great significance for the development of nickel-selenium alloy materials.The research contents and conclusions of this paper:（1）The method of surface blackening in the fine treatment of metal surface has been widely concerned.In this paper,the catalytic properties of blackening substances on metal surface were studied by electrochemical methods.At room temperature,Cu₃Se₂-Ni was synthesized on the surface of nickel foam by metal blackening method.The optimum preparation conditions of catalytic electrode were determined by changing the blackening time.The physical characterization and electrochemical performance test of nickel foam electrode coated with Cu₃Se₂ were carried out.The physical characterization showed that Cu₃Se₂ crystal was uniformly grown on the surface of nickel foam,and the crystal was spherical or blocky particles.Electrochemical characterization shows that when the blackening time is 1.5 h at room temperature,it has a better catalytic hydrogen evolution effect,that is,when the current density reaches-10 m A·cm^-2,the hydrogen evolution overpotential is 556 m V,and the Tafel slope is 187 m V·dec^-1.At high temperature,the starting black liquor was prepared by the same method,and Ni₃Se₂-Ni was prepared by hydrothermal method.By changing the temperature of hydrothermal reaction and the time of blackening,the optimum preparation conditions of catalytic electrode were determined.The physical characterization and electrochemical performance of the Ni₃Se₂-coated Ni foam electrode were tested.The physical characterization showed that Ni₃Se₂ crystals were grown in situ on the surface of Ni foam,and the crystals were flaky and spherical.Electrochemical characterization shows that when the hydrothermal reaction time is 5 min at high temperature,it has a better catalytic hydrogen evolution effect,that is,when the current density reaches-10 m A·cm^-2,the hydrogen evolution overpotential is 205 m V,and the Tafel slope is 71 m V·dec^-1.The Ni₃Se₂-Ni material has a low charge transfer resistance.The stability of the catalyst was tested by cyclic voltammetry and chronoamperometry.The results showed that the hydrogen evolution polarization curve remained basically unchanged before and after 1000 cyclic voltammetry scans.The current density fluctuated little with time after continuous electrolysis for 50 h at constant potential,indicating that the catalyst had good stability.In situ growth of Ni₃Se₂ by hydrothermal method provides a way to prepare high performance hydrogen evolution catalyst.（2）Ni₃Se₂ was successfully synthesized on nickel foam by hydrothermal method.In order to obtain better synthesis effect,Ni₃Se₂-Ni material with better hydrogen evolution effect was synthesized by increasing the surface contact area.The above hydrothermal synthesis experiment was carried out again with nickel powder.The above optimum conditions were selected during hydrothermal synthesis.The powder after reaction was dried,and then the pickling time and the ratio of conductive agent carbon nanotubes were changed to prepare Ni₃Se₂-Ni/CNT electrode sheets under different conditions.The physical test of Ni₃Se₂-Ni material and the electrochemical test of Ni₃Se₂-Ni/CNT electrode sheet were carried out.Physical characterization shows that Ni₃Se₂ crystal is uniformly grown on the surface of nickel powder,and the crystal has a network morphology.Electrochemical characterization shows that when the pickling time is 1.5 h,it has a better catalytic hydrogen evolution effect,that is,when the current density reaches-10 m A·cm^-2,the hydrogen evolution overpotential is152 m V,and the Tafel slope is 20 m V·dec^-1.The Ni₃Se₂-Ni/CNT material has a low charge transfer resistance.The stability of the catalyst was tested by cyclic voltammetry and chronoamperometry.The results showed that the hydrogen evolution polarization curve remained basically unchanged before and after 1000 cyclic voltammetry scans.I-t images also show that the catalyst has good stability.