Design And Preparation Of Nickel-based Bimetallic Nanomaterials And Study On Their Oxygen Evolution Properties

As a renewable energy source,hydrogen energy is the most ideal alternative energy source for traditional fossil energy sources.The water splitting is the most efficient and clean way to produce hydrogen.In the actual industrial water splitting process,the actual applied voltage of water splitting is much greater than its theoretical decomposition voltage,and its adjustable energy consumption mainly comes from the over-potential of the oxygen evolution reaction(OER)at the anode and the hydrogen evolution reaction(HER)at the cathode,In particular,OER with a complex four-electron(4e)transfer process has a slow kinetics and requires a higher overpotential.Therefore,OER and HER are critical to the overall efficiency of water splitting.The OER and HER catalysts are the key to reduce their overpotential.In order to improve the efficiency of water splitting,the design of new high-efficiency electrocatalysts has become a research hotspot in recent years.In this research project,the method of constructing defects is used to design the oxygen evolution catalyst to enhance the oxygen evolution reaction activity and stability of the designed catalyst.The optimization of the electronic structure existing between the bimetals is used to improve the conductivity of the catalyst and make it have a higher oxygen evolution reaction activity.In addition,the two-dimensional sheet structure will expose more active sites,which can not only improve the oxygen evolution reaction activity of the catalyst,but also enhance the stability of the catalyst.In addition,the dual-functional catalyst is designed by co-doping with N and P,and the element N is used to shrink the crystal lattice of the metal center to build more defects,thereby enhancing the reaction activity of the catalyst.(1)In this paper,we obtained a two-dimensional Fe-doped Ni O(GBD-Ni Fex O)nanosheet with grain boundary defects by performing a solvothermal reaction in PEG-200 and then a low-temperature oxidation conversion process for alkaline oxygen evolution reaction in electrolyte.The grain boundary defect area of GBD-Ni Fex O nanosheets can increase the number of active sites of the catalyst and greatly improve its oxygen evolution reaction activity.When not doped with Fe,pure Ni O is a layered stack of flower-like morphology.By changing the amount of Fe doped,the layered flower-shaped morphology gradually dissociates into a single-layer sheet until it sticks together.The single-layer sheet structure has a larger specific surface area,which exposes more active sites,thereby enhancing the oxygen evolution reaction activity and durability of the catalyst;through the appropriate amount of Fe doping,the reaction kinetic rate of the catalyst can be improved,and the conductivity can be increased.For GBD-Ni Fe0.1O nanosheets,the OER catalytic activity in 1 M KOH electrolyte solution is better than Ru O2,when the current density is 10 m A cm^-2,the overpotential is only 274 m V,and the Tafel slope 79.1 m V dec^-1.Cyclic voltammetry was used to scan 2000 cycles,and the polarization curves before and after the scan basically coincided.The chronoamperometry was used to continuously test for 12 h at an overpotential of 274 m V.During the entire test,the current density decreased only slightly and the stability was good.(2)Through solvothermal reaction,we grow Ni Co LDH with one-dimensional nanowire structure on the surface of foamed nickel,and then nitridation and phosphating at different temperatures respectively.Through electrochemical tests,it was found that N-Ni Co P/NF exhibited excellent water splitting activity.For the oxygen evolution reaction,the OER overpotential was 285 m V at 50 m A cm^-2 and 307 m V at 100 m A cm^-2.