Preparation Of Porous Ni-Cu-Ti/La₂O₃ Composite Electrode And Its Catalytic Performance For Hydrogen Evolution

With the growth of the global economy and people’s needs,energy plays an increasingly important role in the development of human society.With the continuous consumption of traditional fossil fuel energy,it is urgent to vigorously develop clean and renewable energy.Hydrogen energy is a kind of secondary energy,which has the advantages of high calorific value,no pollution and extensive access to resources.It is expected in the development of new energy in the future.There are many ways to obtain hydrogen,among which the most common is alkaline hydrolysis.However,the biggest problem of this technology is that the low activity of its catalytic electrode leads to large energy consumption and uneconomic.Therefore,the preparation of electrode materials with high catalytic performance is the core content of developing hydrogen energy.At present,the electrode materials used for hydrogen production by electrolysis of water have some problems,such as high cost of precious metals such as Pt and Pd,high overpotential of hydrogen evolution,poor corrosion resistance and poor stability,which limit the development of hydrogen production technology by electrolysis of water.The Ni-Cu alloy has good corrosion resistance and high hydrogen evolution activity in various acid,alkali and salt solution media,but its comprehensive hydrogen evolution performance needs to be improved.In view of the above problems,this paper took Ni-Cu alloy system as the research object,doped with different transition element powders to improve its hydrogen evolution performance,and selectively added La₂O₃powder and the influence of different content of La₂O₃powder on the electrode were studied and analyzed,in order to prepare porous cathode electrode with high catalytic hydrogen evolution performance.In this paper,Ni-Cu-Ti,Ni-Cu-Ti/La₂O₃porous electrode materials were prepared by powder metallurgy sintering using Ni,Cu,Ti and La₂O₃powder as raw materials.The microstructure and phase composition of the electrode materials were characterized by scanning electron microscopy（SEM）,backscattered electron diffraction（EBSD）and X-ray diffraction（XRD）.The electrocatalytic hydrogen evolution performance of the electrode materials was investigated by electropotentiometric scanning,electrochemical impedance spectroscopy（EIS）and cyclic voltammetry scanning（CV）.The specific research results are as follows:1.The Ni-Cu electrode was doped with Zr,W,Co and Ti powder with the same particle size（3-5μm）to improve the performance.Zr,W,Co and Ti respectively promoted the hydrogen evolution performance of Ni-Cu,but Ti powder had the best effect on the hydrogen evolution performance of Ni-Cu system.When the sintering temperature is 1000℃,m（Ni）:m（Cu）:m（Ti）is 5.5:3.5:1,the porosity reaches 41.8%,and the electrocatalytic performance of hydrogen evolution is the best,the exchange current density is 1.39×10^-3A·cm^-2and the Tafel slope is-71.53m V dec^-1.2.The electrocatalytic performance of porous Ni-Cu-Ti/La₂O₃electrode is improved by adding 5-7μm La₂O₃powder on the basis of 5.5Ni-3.5Cu-1Ti electrode.The peak hydrogen evolution is achieved at the 5.5Ni-3.5Cu-1Ti/9%La₂O₃electrode,and the porosity is 36.5%.The exchange current density is 6.28×10^-3A·cm^-2and the Tafel slope is-63.18 m V dec^-1.When the addition amount of La₂O₃is 1～9%,the open porosity decreases gradually with the increase of the addition amount,but the change is little.Meanwhile,the electrically analytical hydrogen performance is getting better and better.Therefore,the content of La₂O₃ is the main factor affecting the hydrogen evolution performance of 5.5Ni-3.5Cu-1Ti/x%La₂O₃in this region.However,when the addition amount of La₂O₃is 9～15%,with the increase of the addition amount,the amount of material generated does not change much,but the porosity decreases greatly,and the hydrogen evolution performance of 5.5Ni-3.5Cu-1Ti/x%La₂O₃is gradually weakened.Therefore,the open porosity is the main factor affecting the hydrogen evolution performance of 5.5Ni-3.5Cu-1Ti/x%La₂O₃in this area.The addition amount of La₂O₃of 9%is the best addition amount to realize the organic combination of these two aspects,so it can greatly reduce the overpotential of hydrogen evolution.3.Porous 5.5Ni-3.5Cu-1Ti/9%La₂O₃composite electrode material has good stability in 6mol/L KOH solution.The current density of the porous5.5Ni-3.5Cu-1Ti/9%La₂O₃composite electrode remained stable at-0.35A·cm^-2after potentiostatic-0.85V electrolysis for 20h in 6mol/L KOH solution.Discontinuous electrolysis experiments were carried out on the porous 5.5Ni-3.5Cu-1Ti/9%La₂O₃composite electrode at the overpotential of-1.3V.The current density amplitude of the electrolysis curves did not change much and basically remained the same,which indicated that the porous 5.5Ni-3.5Cu-1Ti/9%La₂O₃composite electrode had excellent anti-power performance.