Preparation Of Silver-palladium And Palladium-nickel Nanoparticles By Ionic Liquid Electrodeposition And Their Catalytic Properties

Alloy nanoparticles have high electrocatalytic activity and stability,the particle size and composition of alloy nanoparticles have great impact on its catalytic performance,the preparation of particle size,structure,composition of continuously controllable alloy nanoparticles is still very challenging.1-butyl 3-methyl imidazole chloride([BMIM]Cl)ionic liquid as a new environmentally friendly green solvent,not only can be used as a soft template and co-surfactant involved in the formation of the microreactor in microemulsion,but also can improve the conductivity of electrolyte solution,effectively inhibit the agglomeration of nanoparticles,in the preparation of metal nanoparticles by electrochemical process showed excellent performance.In order to achieve the refinement of alloy nanoparticles,we studied the microemulsion composition and preparation conditions by using electrochemical reduction in the quaternary ionic liquid microemulsion(ILM)system containing[BMIM]Cl ionic liquid.AgPd NPs and PdNi NPs catalysts with good dispersibility,particle size and composition are continuously controlled and have high electrocatalytic activity.The morphology,particle size and composition of AgPd NPs and PdNi NPs catalysts were studied and discussed in detail by a series of analytical methods.A stable quaternary ionic liquid microemulsion(ILM)system was constructed by selecting[BMIM]Cl ionic liquid as co-surfactant.The electrochemical behavior of the ILM system was studied.The results show that silver-palladium and palladium-nickel bimetallic ions can achieve common electrochemical reduction in the ILM system.The addition of ionic liquids contributes to the progress of the reduction reaction.Further studies have found that the electrochemical reduction of silver-palladium metal ions occurs simultaneously on the electrode surface and ILM system solution.The study found that the nucleation density,particle size and composition of AgPd NPs and PdNi NPs changed with the change of current density,deposition time,ionic liquid concentration,water concentration and metal ion molar ratio.The effect of current density and ion liquid concentration on the nucleation density and particle size of AgPd NPs and PdNi NPs is more obvious.The particle size of AgPd NPs and PdNi NPs can be controlled by adjusting the current density and ionic liquid concentration,and the chemical ratio of AgPd NPs and PdNi NPs can be controlled by adjusting the molar ratio of silver-palladium and palladium-nickel metal ions in aqueous solution.The electrochemical preparation of AgPd NPs(10 nm)and PdNi NPs(16 nm)with small particle size and uniform distribution was explored.The effects of different particle size and different molar ratio of AgPd NPs and PdNi NPs on the performance of electrocatalytic oxygen reduction and ethanol oxidation were studied under alkaline conditions.AgPd NPs and PdNi NPs on the electrocatalytic reduction of oxygen and oxidation of ethanol had positive effects,make the catalytic process of ethanol fuel cell more easily,and the smaller particle size of AgPd NPs and PdNi NPs because of its high activity and large active surface area and exhibit better electrocatalytic effect.The catalytic effect of AgPd NPs is obviously superior to that of pure metal nanoparticles catalyst.When the molar ratio of silver to palladium in AgPd NPs is 1:1,the effect of electrocatalytic ethanol is the best.When the molar ratio of palladium to nickel in PdNi NPs is 2:1,the effect of electrocatalytic ethanol is the best.The different molar ratios of AgPd NPs and PdNi NPs have very high electrocatalytic activity and long-term electrocatalytic stability for electrocatalytic oxidation of ethanol.The effects of current density and ionic liquid concentration on the nucleation density and particle size of AgPd NPs in the solution of ILM system were studied.It was found that the nucleation density of AgPd NPs increased significantly with the increase of current density,the particle size also increases;The nucleation density and particle size of AgPd NPs in ILM system solution increased with the increase of ionic liquid concentration.When the concentration of ionic liquid was more than 7.14 wt%,the nucleation density and particle size of AgPd NPs in ILM system solution did not change significantly.Therefore,the suitable electrochemical conditions were explored,and the AgPd NPs with particle size of about 3 nm could be obtained in ILM system solution.The effects of different particle size and different molar ratio of AgPd NPs in the ILM system solution on the performance of electrocatalytic oxygen reduction were studied under alkaline conditions.It was shown that the AgPd NPs in the ILM system solution because of its good synergistic effect had a positive influence on the electrocatalytic oxygen reduction,and the smaller particle size of AgPd NPs exhibited better electrocatalytic oxygen reduction.The catalytic effect of AgPd NPs in ILM system solution is obviously superior to that of pure metal nanoparticle catalyst.When the molar ratio of silver to palladium in AgPd NPs is 3:7,the effect of electrocatalytic oxygen is the best.The AgPd NPs catalyst with good catalytic performance can be prepared by regulating the molar ratio of metal silver to palladium in the ILM system solution.