Study On Modification Of Nickel Telluride And The Performance Of Electrocatalytic Hydrogen Evolution

At present,the problems of energy shortage,environmental pollution,and the greenhouse effect are becoming increasingly serious.Therefore,the scientific community has set off a wave of research on hydrogen energy as the ideal energy source for the future.The hydrogen production technology of water electrolysis is expected to become the main method for green and sustainable hydrogen production due to its advantages of using water as the raw material,cheap and easy to obtain,and simple preparation process.Electrolysis of water to produce hydrogen requires a large amount of energy,so catalysts are required to reduce energy consumption.So far,the precious metal Pt with a small earth reserve has the best electrocatalytic hydrogen evolution performance,but it is expensive and is not conducive to large-scale development and application.Transition metal chalcogenides have attracted widespread attention due to their low price and good hydrogen evolution properties in electrolysis of water.Nickel is considered to be one of the most promising catalytic elements because of its large reserves and high catalytic activity.Among chalcogenides,telluride shows more metallic properties than sulfide and selenide,which is more conducive to electron transfer in electrocatalysis.In addition,due to the low electronegativity of tellurium,the strength of forming the Te-H bond(238 kJ mol^-1)is lower than that of the same family of elements,which is more conducive to the desorption of H atoms in the hydrogen evolution reaction.At present,the methods for improving the electrocatalytic hydrogen evolution performance of materials mainly include increasing the number of active sites,increasing the conductivity of the materials,and optimizing the activity of the catalytic sites.In this thesis,NiTe₂ nanomaterials are prepared and their properties are regulated by means of doping,ion irradiation,and composite g-C₃N₄.Through the study of their electrocatalytic hydrogen evolution properties,the reasons for the performance of the modification methods are discussed.The main contents are as follows:1.The NiTe₂ nanorods are prepared by hydrothermal method and modified by selenium doping.Their electrocatalytic hydrogen evolution performance is studied.The hydrogen evolution performance of NiTe₂ is optimized by adjusting the proportion of selenium in the reaction.When the molar addition amount of selenium is 12%,the obtained Se_12%-NiTe₂ sample has the best catalytic hydrogen evolution activity,the Se_12%-NiTe₂ has an overpotential of 514 mV at a current density of 200 mA cm^-2?relative to reversible hydrogen electrode?,a Tafel slope of 38 mV dec^-11 and good stability.Selenium doping can not only reduce the hydrogen adsorption Gibbs free energy of NiTe₂,but also introduce more active selenium sites.In addition,selenium doping increases the electrochemical surface area of the material and reduces the charge transfer resistance,thus improving the catalytic performance of NiTe₂.2.The NiTe₂ nanorods prepared in the first part are coated on a titanium plate treated with hydrochloric acid.The ion irradiation strategy is used to improve the electrocatalytic hydrogen evolution performance of NiTe₂.After Fe¹⁰⁺irradiation(dose of 4×10¹⁴ ions cm^-2),in 0.5 M H₂SO₄ solution,the Fe-NiTe₂/Ti electrode has an overpotential of 557 mV at a current density of 100 mA cm^-2?relative to reversible hydrogen electrode?,a Tafel slope of 61 mV dec^-11 and good stability.The Fe¹⁰⁺irradiation causes defects and phase interfaces in NiTe₂ nanorods,thereby exposing more active sites.At the same time,the introduced Fe ions changes the electronic structure of the NiTe₂,and then affects the material's electrocatalytic hydrogen evolution performance.3.Prepare NiTe₂/g-C₃N₄ composite and study its electrocatalytic hydrogen evolution properties.Graphite-phase carbon nitride?g-C₃N₄?is prepared by melamine pyrolysis,and flakes of g-C₃N₄ are obtained after ultrasonic peeling and freeze-drying treatment.Three-dimensional NiTe₂/g-C₃N₄ composite with high specific surface area is obtained by ultrasonic mixing treatment of g-C₃N₄ and NiTe₂ nanorods,and its electrocatalytic hydrogen evolution performance is tested.The g-C₃N₄ can improve conductivity of the material,thereby ensuring rapid charge transfer during its catalysis process.The specific3D structure of NiTe₂/g-C₃N₄ exposes more active sites in the electrolyte.It accelerates the adsorption rate of H⁺in the electrolyte to the active site and the rapid release of bubbles formed from the surface.In 0.5 M H₂SO₄ solution,the NiTe₂/g-C₃N₄ electrode has an overpotential of 648 mV?relative to the reversible hydrogen electrode?at a current density of 200 mA cm^-2.The Tafel slope is 68 mV dec^-1.