Preparation Of Nickel-based And Cobalt-based Rare Earth Composite Electrodes And Their Application In Electrocatalytic Sodium Metaborate

Hydrogen energy has attracted widespread attention due to its clean,pollution-free,high calorific value,and wide range of sources.Sodium borohydride is a hydrogen storage material with a high hydrogen content,but its expensive price limits its wide application in industrial production.Therefore,the electrocatalytic reduction of sodium metaborate to prepare sodium borohydride has become a hot topic in current research.In this dissertation,different nickel-based and cobalt-based composite electrodes were prepared by electroless plating and electrodeposition using copper as the matrix in anhydrous ethanol.At the same time,rare earth elements such as yttrium,scandium,yttrium,ytterbium,and lanthanum were used to prepare five kinds rare earth composite electrode.The surface morphology and composition of the composite electrode coating were characterized by scanning electron microscopy and energy dispersive spectroscopy.Based on this,the corrosion resistance of the composite electrode was studied;and it was applied to the electrolysis of sodium metaborate,and the principle of sodium metaborate electrolysis was studied.Electrochemical synthesis is mainly an interfacial reaction.The biggest difficulty in cathode reduction of sodium metaborate is that the anion BO₂^-is repelled at the cathode.Due to the repulsion of BO₂^-at the cathode under direct current,electrocatalytic reduction is difficult to occur and the pulse current is therefore selected during the electrolysis experiment.Papers are mainly divided into the following sections:1.Nickel-based rare earth composite electrodes La-Ni-B and Pr-Ni-B were prepared by electroless plating.The process for preparing the composite coating is preferred,the best formulation for electroless plating is obtained,and the effect of addition of La on the composition,structure and morphology of the alloy is also studied.The results show that the alloy film coating has been successfully loaded on the surface of the copper substrate,and the addition of rare earth has a positive synergistic effect on the coating.The addition of rare earth effectively improves the surface morphology of the coating and makes the surface of the coating more uniform.In this chapter,the influence of Pr-Ni-B electrode on the electrolysis of sodium metaborate was also studied.The electrolysis process was studied by pulse frequency,electrolysis time,rare earth content and electrode reusability.The results show that the pulse current is suitable for the electrocatalytic reduction reaction,and the composite electrode prepared with the rare earth content of 3g/L has the best effect.At the pulse frequency anode time T₁=1 s,the cathode time T₂=1 s,the most The best electrolysis time is 5 h.Characterization of the electrode after repeated use showed that the morphology did not change much,indicating that the electrode's reusability was better.2.Cobalt-based rare earth composite electrodes Ce-Co-B and Sm-Co-B were prepared by electroless plating.Using scanning electron microscopy to characterize the surface morphology of the composite electrode and comparing it with the Co-B composite electrode,the results show that the alloy film coating has been successfully loaded onto the surface of the copper substrate and the elements of the coating have been determined using an energy spectrometer.The corrosion resistance of rare earth composite electrodes Ce-Co-B and Sm-Co-B was studied.The effects of pulse frequency,electrolysis time,plating time and electrode repetition rate on the electrolysis behavior were studied.The results show that the composite electrode prepared with rare earth content of 3g/L has higher corrosion resistance,the best pulse frequency anode time T₁=1 s,cathode time T₂=1 s,Composite electrodes can be reused 4 times.3.The Gd-Mg-Ni composite electrode was prepared by electrodeposition in choline chloride/urea ionic liquid.The surface morphology and the elemental composition of the composite electrode were characterized by SEM and EDS.The effects of different deposition times on the surface morphology of composite coatings,and the effects of electrodes and current sensitivity prepared at different deposition times on the electrolysis behavior were studied.The results show that the effect of electrocatalytic reduction of sodium metaborate is best when the deposition time is 20minutes,and the electrolysis effect decreases with the increase of current sensitivity.4.The cyclic voltammetry and linear voltammetry were used to study the electrochemical behavior of sodium metaborate alkaline solution and sodium borohydride alkaline solution on the gold electrode.As a result,it was found that sodium borohydride has a significant oxidation peak at a potential of-0.4 V,and that its peak current is linearly related to the corresponding concentration of sodium borohydride.This method is suitable for the quantitative analysis of trace amounts of sodium borohydride in the electrolyte.Concentration,detect sodium borohydride concentration range.The linear equation is 1×10^-49×10^-4 mol/L,The linear equation is Y_{10^-4 mol/L}=1.95×10^-3+82.5X?X:mA?,R=0.9984.The relative error of the measurement result is 1.69%;The linear equation is 1×10^-39×10^-3 mol/L,The linear equation is Y_{10^-3 mol/L}=y=0.024+77.2X?X:mA?,R=0.9989.The relative error of the measurement result is 3.44%,and the relative error is less than 5%,indicating that this method is suitable for the detection of trace sodium borohydride.