Studies On Preparations And Electrochemical Performances Syntheses Of Heterometal-doped Transition Metal-based Electrocatalysts

At present,the main energy supply comes from fossil fuels,but the use of fossil fuels releases a large amount of CO₂ and other greenhouse gases,causing environmental pollution,climate warming and other problems.Scientists are working to develop a new energy source that is green,renewable and environmentally friendly.Hydrogen as a clean and efficient energy carrier has been attracted wide attention.Water electrolysis technology is expected to become a sustainable way of hydrogen production.However,the common technology of electrolysis water hydrogen production has such problems as low electrolysis efficiency and high energy consumption,many researches focus on improving the energy conversion efficiency of electrolysis water and reducing the cost of hydrogen production.This thesis mainly apply in hydrothermal method and solid method,electrodeposition method and other chemical method.V,N-CoP/CC,Ir-CoC,Ir-VCo?OH?₂/CC nanomaterials with unique nanostructures were synthesized by metal doping and modification.The morphology and structure of the materials were characterized,and the electrochemical properties were tested and analyzed to judge the electrochemical properties of the materials.The electrochemical catalysts studied in this paper are as follows:?1?A two-step method was used to prepare V and N co-doped CoP nanomaterial?V,N-CoP/CC?supported by carbon cloth.The V and N doping in V,N-CoP/CC is helpful to enhance the electron interaction and charge transfer,which is beneficial to the catalytic performance of hydrogen evolution.In addition,V,N-CoP/CC provides subtle lattice distortion as an additional active site.Electrocatalytic test showed that the prepared V,N-CoP/CC nanometer material was a pH universal electrocatalyst with excellent performance.When the current density was10 m A cm^-2,the overpotential was 57 mV under alkaline conditions?1 M KOH?,81mV under acidic conditions?0.5 M H₂SO₄?,and 146 mV under neutral conditions?1 M PBS,pH=7?.The Co-doping method proposed in the experiment opens up a broad prospect for the development of efficient and inexpensive pH universal electrocatalysts.?2?The solid phase synthesis method was used to grind and mix the carbon carrier and metal particles directly in the agate mortar at room temperature,so that the metal particles were highly dispersed on the carbon carrier,and the Ir-doped CoC metal nanoparticles?Ir-CoC?were generated.This method is simple and efficient.Both Co and Ir in the Ir-CoC nanomaterial catalyst can be used as active sites and effectively enhance the stability and specific surface area of the material.It was verified by systematic electrochemical test that when the current density was 10 mA cm^-2,the overpotential in acidic medium was 14 mV and that in alkaline medium was39 m V,showing excellent catalytic performance of HER.The tafel value of Ir-CoC is36.43 mV dec^-1,which has strong HER dynamics.The results show that Ir doping improves the electrochemical dynamics,additional active centers,and accelerates the charge transfer,thus effectively improving the electrocatalytic performance.?3?Ir-VCo?OH?₂/CC was prepared by electrochemical deposition with V-Co?OH?2/CC prepared by hydrothermal method as the precursor.The prepared nanorods have rough surface and maximized specific surface area,which can effectively promote ion and gas transfer.The material exhibited excellent electrochemical properties.When the current density was 10 mA cm^-2,the overpotential?1 M KOH?under alkaline conditions was 37 mV,and the tafel value was40.2 m V dec^-1,showing strong HER dynamics.In the 60 h i-t test,Ir-VCo?OH?₂/CC showed long-term stability.It is a high performance and low cost electrochemical catalyst with a simple synthesis route and great development potential.