Synthesis And Electrocatalytic Hydrogen Evolution Performance Of Coal-based Carbon Fiber Supported Molybdenum Disulfide Composite Materials

With the development and utilization of fuel cells,hydrogen energy has played an important role.Among the methods for preparing hydrogen,the electrolysis of water to produce hydrogen is considered an important method.Hydrogen is produced by electrolysis of water.Due to the existence of the initial overpotential of hydrogen evolution,a large amount of electric energy is severely consumed.Therefore,researchers usually use suitable catalysts to solve the energy consumption problem.In the choice of catalyst,the advantage of the noble metal Pt is that it has better catalytic activity,but the disadvantage is that it has a small reserve of olefin and is expensive,and it cannot be used commercially in industrial production.Therefore,recent studies have shown that the transition metal chalcogenide compound MoS₂ has good catalytic activity due to its large surface area and more active sites.It is well known that MoS₂has a variety of phase structures,the more common ones are 2H phase and 1T phase.However,since 2H MoS₂ is a semiconductor phase,the conductivity is poor and the catalytically active sites are located at the edge of the layered structure,which results in the lower catalytic performance of the catalyst.On the contrary,1T MoS₂ has better conductivity and larger interlayer spacing.However,1T MoS₂ belongs to the metastable phase and is not easy to synthesize.Therefore,the preparation and performance research of 1T MoS₂ has gradually become a research focus.In this paper,various composite materials of 1T@2H MoS₂ were prepared by supporting on non-metal doped coal-based carbon fiber,ZIF-8 controlled coal-based carbon fiber.The main research contents of this paper are as follows:(1)N,P dual doped coal-based carbon fiber supported 1T@2H MoS₂ nanosheets(NPcoal-CFs-1T@2H MoS₂)have been synthesized via electrospinning technology,calcination and solvothermal method.Among them,the existence of 1T phase is considered to be an effective strategy to optimize the catalytic activity of the catalyst.The addition of coal-based carbon fiber can effectively prevent the agglomeration of1T@2H MoS₂ nanosheets and improve the conductivity of the catalyst.The doping of N and P atoms on the carbon support accelerates the transfer of electrons.The prepared composite catalyst has certificated excellent hydrogen evolution performance with a low Tafel slope of 64.6 m V dec^-1 and a small overpotential of 216 m V at a current density of10 10 m A cm^-2.In addition,the catalyst maintains good stability in 0.5 mol L^-1 H₂SO₄solution.(2)1T@2H MoS₂ nanosheets-loaded ZIF-8 regulated coal-based carbon fiber(ZIF-8coal-CFs-1T@2H MoS₂)have been synthesized via electrospinning technology,calcination and solvothermal method.Among them,ZIF-8 is rich in nitrogen and carbon,and it will form a porous structure after calcination,so the fiber obtained by adding ZIF-8 during spinning will obtain N-doped porous coal after carbonization.Carbon fiber not only helps to improve the conductivity of the catalyst,but also the porous structure of coal-based carbon fiber as a carrier to support 1T@2H MoS₂ nanosheets greatly reduces the serious accumulation and agglomeration of the nanosheets,and the porous is more helpful for the rapid electron transmission.The prepared ZIF-8_0.3coal-CFs-1T@2H MoS₂ has a low Tafel slope of 60.4 m V dec^-1 and a small overpotential of 219 m V at a current density of 10 m A cm^-2,and has excellent hydrogen evolution performance.In addition,the catalyst maintains good stability in 0.5 mol L^-1H₂SO₄solution.(3)The ZIF-8NPcoal-CFs-1T@2H MoS₂ composite material was controllably synthesized by electrospinning,high temperature calcination and one-pot hydrothermal,in which 1T@2H MoS₂ nanosheets with enlarged interlayer spacing were grown vertically on N,P dual doped ZIF-8 modulated porous coal-based carbon fiber support.Due to the synergistic effects of porous structure and electronic,the prepared electrocatalyst exhibits excellent HER performance in 0.5 mol L^-1 H₂SO₄ solution.When the current density is 10 m A cm^-2,the catalyst has a low Tafel slope of 57.3 m V dec^-1,a small overpotential of 202 m V and good stability.