Preparation Of Ni-based Nanofiber Catalyst And Application Of Oxygen Evolution In Electrolytic Water

In order to reduce the over-exploitation of fossil resources and their negative impact on the environment,environmentally friendly renewable energy has become the focus of international attention.The development and application of hydrogen energy with zero emission has become the most promising direction,and the best choice for hydrogen energy application is the electrolysis of water to produce green hydrogen.However,the anodic oxygen precipitation reaction（OER）in the electrolysis reaction has a slow kinetic characteristic,which affects the efficiency of water electrolysis.To improve the efficiency of OER,industry often uses precious metals and their compounds as effective catalysts,such as Pt,Ir and Ru.However,the high cost and low reserves of these noble metals make it difficult to meet the requirements of expanded applications.In this study,we selected Ni,which has abundant reserves,low price,good stability and characteristic electronic structure,as the base element,and also compounded two transition elements,Fe and Cu,to prepare Ni-Fe-C and Ni-Cu-C composite nanofiber catalysts and study their organization and OER performance.（1）With polyvinyl alcohol（PVA）as the substrate,nickel acetate and copper acetate as the effective ion source,and deionized water as the solvent,a series of PVA solutions and metal salt/PVA solutions with different concentrations were prepared to study the spinning performance and determine the optimal spinning parameters:10 wt%PVA solution with metal salt concentration of 0.6 mol/L,voltage of 23-27 KV,feed rate of 0.0008-0.0012 mm/s,and spinning distance of 15 cm.（2）The precursor fibers（Ni Cu/S-PVA fibers）were prepared by electrostatic spinning technique using polyvinyl alcohol,nickel acetate and copper sulfate as raw materials.The precursor fibers were carbonized by high-temperature atmosphere to produce Ni-Cu-C type nanofibers containing Ni₃S₂ composition.Ni-Cu-C type nanofibers exhibited a nanoporous and sparse structure.The Ni-Cu-C type nanofibers were made into electrodes and OER activity tests were carried out in 1 M KOH solution,and the results showed that the overpotential at a current density of 10 m A cm^-2 was 373 m V and the Tafel slope was 164 m V dec^-1.（3）The precursor fibers（Ni Fe/S-PVA fibers）were prepared by electrostatic spinning technique using polyvinyl alcohol,nickel acetate and ferrous sulfate as raw materials.The precursor fibers were carbonized by high-temperature atmosphere to prepare Ni Fe carbon nanofibers with Fe_4.5Ni_4.5S₈.The Ni-Fe-C type nanofibers exhibited a nanodendritic structure.The OER activity test was carried out by making Ni-Fe-C type nanofibers into electrodes in 1M KOH,and the results showed that the overpotential at a current density of 10 m A cm^-2 was258 m V and the Tafel slope was 96 m V dec^-1.The study found that polyvinyl alcohol has excellent spinning properties,and electrostatic spinning technology provides a simple and effective method for preparing one-dimensional fiber materials.The fibers are carbonized at an high temperature,and the electrical conductivity and the dispersion of the active metal of the carbon fibers are significantly improved.The sulfate decomposition provides the sulfur source for the regime,while the sulfide generation effectively improves the catalytic activity of the material.