Preparation And Catalytic Properties Of Ni|MnO/CNT Nanomaterials

Water electrolysis is considered to be one of the most promising technologies for producing high-purity hydrogen and oxygen.However,practical industrial water electrolysis is greatly hindered by the slow kinetics and high overpotential of the oxygen evolution reaction（OER）.Therefore,it has become a great challenge to develop high-efficiency oxygen evolution electrocatalysts that can accelerate the reaction rate at low overpotentials with good stability.In this dissertation,the oxygen evolution reaction of water electrolysis is taken as the research object,and metal and metal oxide heterostructured oxygen evolution electrocatalysts supported on carbon nanotubes（CNTs）are designed.The main research results are as follows:（1）The optimal process for uniformly coating Ni|MnO heterostructured nanoparticles on CNTs by liquid-phase reduction method was explored.When the ion concentration of the plating solution is0.15mol/L,the sodium borohydride dropping rate is 400μL/min,and the CNTs are sintered at 400℃in the H₂/Ar atmosphere,the Ni|MnO heterostructure with a size of about 10nm can be uniformly coated on the CNTs.Nanoparticles provide a large number of active sites for catalytic reactions.（2）The Ni_0.95|Mn_0.05O/CNT material with efficient electrocatalytic oxygen evolution performance was prepared.In 1M KOH electrolyte,the current density of 10m A cm^-2 can be achieved with only an overpotential of 293m V.It has a slope of 55.6m V dec^-1 and good stability,outperforming commercial Ru O₂(overpotential of 356m V at a current density of 10m A cm^-2).（3）The first-principles calculation results show that:（a）The coupling effect between Ni and MnO in the heterostructure changes the valence state of part of Mn,generating oxygen vacancies that are more conducive to the adsorption of oxygen atoms,thereby improving the Catalytic performance;（b）When Ni is converted into Ni O,the center of the d-band near the Fermi level decreases,which is not conducive to the electron transfer near the d-band and hinders the progress of the catalytic reaction.At the rate-determining step*OH→*O,the free energy of reaction rises from 1.741e V to 1.859 e V,leading to a rise in the overall energy barrier for the OER process.40 Figures,6 Tables,133 References are contained...