Preparation And Catalytic Properties Of Nano Ni-Co Alloy Powder

Hydrogen is the cleanest and greenest energy source,and electrochemical or photochemical methods are considered the most friendly methods for large-scale efficient hydrogen production.The research of electrochemistry mainly focuses on a variety of highly efficient and stable electrocatalysts,which can produce hydrogen on a large scale,and improve the catalytic activity by improving the structure and morphology of the electrocatalysts.As the current research hotspot,3d-group transition metal catalysts still have some problems,such as poor contact between catalyst and electrolyte,small loading area,poor stability and so on,which lead to the great reduction of catalytic activity.The electrocatalytic activity can be effectively improved by using three-dimensional conductive materials supported on transition metal catalysts.In this paper,nano-Ni-Co alloy powder supported on glassy carbon electrode and porous nickel substrate was used to prepare bifunctional electrocatalysts.The effects of different preparation processes on the catalytic performance of electrolytic water were studied,the main research contents are as follows:（1）Nano Ni-Co alloy powder was prepared by chemical coprecipitation-thermal decomposition method.The morphology,size and structure of nano-Ni-Co alloy were adjusted by adjusting process parameters such as p H,Ni-Co ratio and decomposition atmosphere,and the influence of process parameters on nano-Ni-Co alloy powder and its law were analyzed.（2）The catalytic properties of nano-Ni-Co alloy powder were studied.Because different process parameters were correspond to different structures and morphologies of nano-Ni-Co alloy,by analyzing showed that the hydrogen evolution and oxygen evolution properties of nano-Ni-Co alloy powder with different structures and morphologies as catalytic electrodes were studied.The results showed that in 0.5 M H₂SO₄,the overpotential of Ni CO_p3alloy only need 184.7 m V to reach the current density of 10 m A·cm^-2of HER reaction,and the Ni CO_p3alloy corresponding Tafel slope is 129.92 m V dec^-1.For the OER reaction,the OER current density of 30 m A·cm^-2can be achieved with 418 m V overpotential,at which time the Tafel slope is 247.40 m V dec^-1.In 1 M KOH,Ni CO_p3alloy an overpotential is 276 m V,the Tafel slope of the Ni CO_p3alloy at 40 m A·cm^-2current density is 247.1 m V dec^-1.Therefore,the preparation conditions of catalysts with the most efficient catalytic properties are p H=9.5,Ni:Co=1:1 and hydrogen gas in the thermal decomposition atmosphere.The prepared catalyst has a complete structure,a three-dimensional porous structure,and a high specific surface area,which is more conducive to ion adsorption/desorption.（3）The nano-Ni-Co alloy powder was loaded on porous nickel by physical method with porous nickel as the base and nano-Ni-Co alloy powder as the supported catalysts.The catalytic properties of nano Ni-Co alloy powders with different structures and morphologies as catalytic electrodes were studied.It was concluded that the HER and OER properties of 3D Ni CO_p3alloy were the best.For HER reaction,when current density is 10 m A·cm^-2,the overpotential of 3D Ni CO_p3alloy is 64.6 m V,and the Tafel slope of HER reaction in acidic medium is 90.45 m V dec^-1at 0.5 M H₂SO₄.For OER reaction,the overpotential is 588 m V at100 m A·cm^-2current density,and the Tafel slope of OER reaction in acidic media is 197.26m V dec^-1.In 1M KOH,the OER reaction was at 40 m A·cm^-2with an overpotential of 140.8m V and a corresponding Tafel slope of 123.13 m V dec^-1.This electrode is more favorable for catalyst dispersion and does not poison the active site.