Synthesis And Electrocatalytic Hydrogen Evolution Performance Of Black Phosphorus-based Composites

At present,with the advancement of science and technology,the demand for energy is increasing,and the existing non-renewable energy sources such as coal and fossil fuels are decreasing day by day,which also brings environmental pollution and other problems.Non-renewable energy,hydrogen energy has attracted people's attention due to its high efficiency and cleanliness.Hydrogen production by electrolysis of water is a hot spot in the development of new energy.However,the overpotential required for electrolysis of water and the high cost of precious metal catalysts limit its large-scale application.Therefore,the development of low-cost non-precious metal catalysts with high catalytic activity and high stability has very important research significance and application prospects.Black phosphorus(BP)is widely used in catalytic hydrogen production due to its high carrier rate and unique electronic structure,but it is easily oxidized when exposed to air and water.It needs to be optimized or doped with other non-precious metals to form the composite material thus reducing the Gibbs free energy of hydrogen evolution.In this paper,the catalysts were characterized by Fourier transform infrared spectroscopy(IR),X-ray diffraction analysis(XRD),scanning electron microscopy(SEM),and elemental analysis(EDS).The hydrogen evolution performance of the catalyst was analyzed.The main research contents and discussions are as follows:(1)Amino-modified MoS₂ was synthesized by conventional solution method,and NH₂-MoS₂@BP catalyst was prepared by hydrothermal synthesis method.The structure and properties of the materials were analyzed by IR,XRD,SEM,EDS and electrochemical performance tests,and the optimal doping amount of BP nanosheets was explored.The characterization by IR,SEM and XRD showed that the NH₂-MoS₂@BP catalyst had a uniformly distributed lamellar structure,the morphology and structure of the raw material were not changed after doping of BP nanosheets,and the catalyst crystallinity was good.Electrochemical tests show that the hydrogen evolution overpotential is 450 mV at a current density of 10 mA·cm^-2,the Tafel slope decreases from 119 mV·dec^-1 to 95mV·dec^-1,and the optimal doping amount of BP is 20 mL,the increased electrochemical activity can be attributed to the large specific surface area of the NH₂-MoS₂@BP catalyst,the larger number of active sites,and the better stability of the catalyst in acidic media.(2)Iron-nickel alloys and FeNi/C@BP catalysts were synthesized by hydrothermal synthesis.IR and XRD characterizations show that the phase structure of the samples does not change after doping with BP nanosheets.SEM characterizations show that FeNi/C@BP catalysts have a pore structure,and the electrolyte can enter and exit the pores,thereby increasing the contact area between the electrolyte and the catalyst.The reaction rate is improved,and the catalytic reaction is facilitated.The electrochemical test results show that the optimal doping amount of BP nanosheets is 20 mL,and the hydrogen evolution overpotential is 244 mV at a current density of 10 mA·cm^-2,which is 94 mV·dec^-1 lower than that of the raw materials.Through the CV cycle curve it is calculated that FeNi/C@BP-20 has a larger active area,which is beneficial to ion diffusion,and the FeNi/C@BP catalyst has better stability in alkaline medium.(3)Ni₂Al-LDH@BP catalysts with different Ni-Al molar ratios were synthesized by the hydrothermal synthesis method from the precursor Ni₂Al-LDH and black phosphorus nanosheets.The phase structure,morphology,element composition and electrochemical performance of the material were characterized.The structure showed that the Ni₂Al-LDH@BP catalyst was a flower-like sheet structure,and the black phosphorus nanosheets did not change the structure of the raw material;Ni₈Al-LDH@BP catalyst has excellent catalytic performance in 1.0 M potassium hydroxide electrolyte,at the current density of 10 mA·cm^-2,the overpotential of hydrogen evolution is 258 mV,and the Tafel slope is 71mV·dec^-1,which can be attributed to the synergistic effect between black phosphorus nanosheets and double hydroxides to promote electron migration and charge transfer,thus improving the activity of the catalyst.