Preparation And Application Of Monodisperse Nickel Based Nanocrystals

Traditional catalytic materials are difficult to obtain ideal catalytic effect in catalytic reaction because of their larger macro dimension.Those small size of nanometer materials have higher specific surface area,low coordination environment and quantum effects,etc.,So that it has a distinct advantage in the field of catalysis.Therefore,the synthesis of monodisperse or near-monodisperse nanoparticles has gradually become one of the hotspots in the field of scientific research.However,most of these materials come from organic solution phase reduction,and the complexity and cost of synthesis make it difficult to realize industrial applications.Therefore,it is of great significance to develop a general synthesis method for monodisperse nanomaterials with low coordination environment.The research focus of this project is to develop a general synthesis method of monodisperse nickel-based nanocrystals.We realized the general synthesis of NiRu,NiFe and NiCo monodisperse nanocrystalline.Good applications have been made in the fields of CO2 methanation,electrocatalytic oxygen evolution and supercapacitors.Focuses on the evolution process of the nano materials in catalytic reaction,characterization analysis and theoretical calculation,the element synergies and carrier effect of a good interpretation.In the first phase of the experiment,3 nm monodisperse Ni nanocrystalline was prepared with the hot-inj ection method already in the literature,oleylamine as the solvent and surfactant,DMF solution of sodium borohydride as the reducing agent.A small amount of Ru was introduced and the material was applied to the methanation of carbon dioxide.The results showed that the introduction of a small amount of Ru not only significantly improved the dispersion of nickel nanoparticles,but also significantly improved the methanation activity and selectivity of methane dioxide.In the second stage experiment,different mole ratio of 4 nm NiFe nanoparticles was prepared by the same synthesis method.This material shows excellent electrocatalytic performance for oxygen evolution reaction under alkaline conditions,in which the overpotential of Ni0.4Fe0.6 under current density of 20 mA/cm2 is only 231 mV,which is better than most existing literature reports.In the third phase of the experiment,4 nm NixFe(1-x)@NixFe(1-x)O magnetic nanoparticles was synthesized by using DMF as the solvent and surfactant and sodium borohydride as the reducing agent.Optimized by the composition effect,the Ni0.7Fe0.3@Ni0.7Fe0.3O/NF exhibits excellent activity for OER,requires only 215 mV at 10 mA cm-2 in 1.0 M KOH.Moreover,the underlying mechanism was carefully studied by XRD,Raman,XPS,XANES analysis and DFT calculations.Due to the self-magnetic attraction,the catalyst show outstanding stability throughout the electrocatalysis,surpassing than most self-supported catalysts.And the small size of NixFe(1-x)@NixFe(1-x)O nanoparticels bring the catalyst more exposed active sites,thus excellent activity.In the fourth stage experiment,4nm NiCo nanoparticles was synthesized by the likely method.Because of its characteristic of pseudo capacitance of nickel-based materials in electrocatalysis,this material was applied to the field of supercapacitors,showing good charge-discharge specific capacity and cyclic stability.At the same time,a novel concept of NiCo based supercapacitor material prepared by OER activation is proposed.Finally,using activated carbon material as the negative electrode and nickel-cobalt material as the positive electrode,the assembly of asymmetric supercapacitors was introduced.Through continuous optimization of the synthesis method of nickel-based nanoparticles,monodispersed nickel-ruthenium and nickel-iron nanoparticles were synthesized in the olamine system and the monodispersed nickel-iron and nickel-cobalt nanoparticles were synthesized in the DMF system,and excellent catalytic performance was obtained in the fields of CO2 methanation,electrocatalytic oxygen evolution and supercapacitors.