Preparation Of Transition Metal Electrode Materials And Research Of Their Hydrogen Evolution Reaction

The key factor for harmony between humans and nature is recycling sustainable and clean energy.Hydrogen can be solved by high energy density,non-polluting hydrogen energy that comes from global warming and over-dependence on traditional energy sources.It is the most efficient way to produce hydrogen from water-splitting.The overpotential can be effectively reduced by transition metal in the reaction of hydrogen evolution.It significantly reduces the consumption of electricity.However,the transition metal electrode materials still have defects such as small specific surface area and few active sites currently.In the first part of this paper,specific surface area is increased by electrodeposition of copper dendrites on nickel foam.Subsequent,cobalt-nickel co-deposition was used to increase the active site In the second part,a bimetallic organic framework（CoNi-MOF）was prepared with cobalt-nickel element as the active center and p-terephthalic acid（PTA）as the ligand,and then the MOF conductivity was enhanced and the hydrogen precipitation overpotential was reduced by phosphorylation treatment.（1）CoNi/Cu/NP electrode with high specific surface area was prepared in two steps.Firstly,hydrogen bubble molding method was used to produce copper dendrites with high specific surface area,then nickel and cobalt elements were continued to be deposited on copper dendrites to increase the active sites of electrocatalyst.The structure of copper dendrite was influenced by the precipitation rate of hydrogen bubbles on the cathode surface and the mass transfer rate of copper ions.The specific surface area and capacitance of copper dendrites were maximized when the deposition current density was 140 mA/cm~2.The morphology and elemental content of nickel and cobalt co-deposition are influenced by the salts concentration and current density.The CoNi/Cu/NP electrode has the best electrochemical performance that prepared by a cobalt salt concentration of 0.3 M and a current density at 20 mA/cm~2.The overpotential is only 76 mV at a current density at 10 mA/cm~2tested in a 1.0 M KOH electrolyte.Electrochemical impedance spectroscopy and electric double layer tests show that the electrode material has the smallest charge transfer resistance and the largest capacitance value.It was found thatη₁₀₀only increased by 6%after 1000-turn CV test,indicating that the hydrogen precipitation electrode has good stability.（2）Sheet-like bimetallic MOF were prepared using cobalt nitrate,nickel chloride and PTA.The synthesis of[M₃（PTA）₂（OH）₂·4H₂O]-type MOF structures was analyzed by FTIR spectroscopy and XRD analysis.The phosphorylated MOF formed a carbonized substrate,which increased the electrical conductivity of the material;the formation of Co-P and Ni-P bonds in the MOF structure was confirmed by XPS,and the phosphorus-nickel-cobalt formation compound effectively reduced the overpotential of HER.The experiment results show that the Ni₈Co₄-P has the maximum specific area,and the overpotential of the phosphorylated sample（Ni₈Co₄-P）is 91 mV only when tested in 1.0 M KOH electrolyte with a current density at 10mA/cm~2,and the catalyst has good catalytic activity and stability with only 2%decrease in current density after 8 h of chronoamperometry test.