Preparation And Electrocatalytic Performances Of FeCoNiB/P Based High Entropy Amorphous Alloys

Because of energy consumption and environmental pollution problems,the development of clean energy becomes one of the most important subjects.Hydrogen,as a clean energy source,has attracted great attention.Electrolyzed water to produce hydrogen is a very promising technology to produce hydrogen,which is composed of two parts of the reaction of oxygen evolution reaction（OER）and hydrogen evolution reaction（HER）.Due to polarization,additional electrical energy is consumed during the electrolysis of water to overcome energy barrier.Therefore,the key to increasing the OER and HER reaction rate is to develop inexpensive and environmentally friendly electrocatalytic material with stable structure to reduce the energy barrier for electrolysis of water reactions.Nowadays,the most widely utilized electrocatalysts are noble metals and their oxides.But high costs of these noble metals,limit the development of electrolyzed water processes.Researchers are focusing on developing catalysts without any noble metals.Focusing on the concept of high entropy alloys,this paper systematically studies the preparation and electrocatalytic properties of Fe Co Ni B/P high entropy amorphous alloys using spin quenching method and mechanical alloying method.High entropic effect and the amorphous structure having a large number of unsaturated sites,reduce the energy barrier of the electrocatalytic reaction,and effectively improve the reaction rate of OHE and HER.Cyclic voltammetry measurements are used to electrochemically activate alloys,resulting in the reconstruction of the catalyst surface,increasing the electrochemical activity site of the catalyst,and further improving the OER or HER catalytic activity of alloys.（Fe Co Ni）₈₀B₂₀,（Fe Co Ni Cr）₈₀B₂₀ and（Fe Co Ni Cr V）₈₀B₂₀ alloys were successfully prepared by spin quenching method.Among them,（Fe Co Ni Cr V）₈₀B₂₀ exhibited excellent catalytic activity and reaction kinetics in the OER process,the overpotential at current density of 10m A cm^-2 was 311m V,and the Tafel slope was 49.1m V dec^-1,better than（Fe Co Ni）₈₀B₂₀ and（Fe Co Ni Cr）₈₀B₂₀.After electrochemically activation,the OER catalytic activity of（Fe Co Ni Cr V）₈₀B₂₀ further improved,the overpotential reduced to 237m V,and the Tafel slope reduced to 24.2m V dec^-1.Cyclic voltammetry activation induced surface reconstruction on surface of（Fe Co Ni Cr V）₈₀B₂₀,including selective leaching of elements,growth of metal hydroxyl oxides and hydroxides as OER active substances,growth of nanoparticles,formation of porous structures,and the introduction of oxygen vacancies,which promoted the rate of electron transfer in the OER process.（Fe Co Ni Cr V）₈₀B₂₀ also had excellent stability of OER catalytic activity,and can remain 95.5%catalytic activity after 20 hours stability test.（Fe Co Ni Cr）₇₆B₂₀Ru₄ was successfully prepared by spin quenching method.It has better HER catalytic activity,with an overpotential of 179m V at the current density of10m A cm^-2,and a Tafel slope of 85.2m V dec^-1,which is better than（Fe Co Ni）₈₀B₂₀,（Fe Co Ni Cr）₈₀B₂₀ and（Fe Co Ni Cr V）₈₀B₂₀.Electrochemical activation of（Fe Co Ni Cr）₇₆B₂₀Ru₄ by negative potential cyclic voltammetry was utilized,and the HER catalytic activity was further improved,the overpotential was reduced to 43m V,and the Tafel slope was reduced to 44.8m V dec^-1.A small amount of actively catalytic element Ru enhanced the HER catalytic activity of the alloy.After being activated by the cyclic voltammetry with negative potential,the valence state of Ru element positively shifted,the catalytic activity of the element improved,and the synergistic effect between metallic elements is enhanced.Electrochemical activation led to a further increase in the electrochemical activity area of（Fe Co Ni Cr）₇₆B₂₀Ru₄,with an accelerated electron transfer rate.In addition,（Fe Co Ni Cr）₇₆B₂₀Ru₄ also had a OER catalytic activity,with an overpotential of 347m V at a current density of 10m A cm^-2 and a Tafel slope of60.7m V dec^-1.After activation,the overpotential reduced to 295m V and the Tafel slope reduced to 41.2m V dec^-1.HER and OER catalytic performances indicated（Fe Co Ni Cr）₇₆B₂₀Ru₄ is a bifunctional catalyst with both HER and OER catalytic activities.Fe Co Ni Cr P and Fe Co Ni Mn P nanoparticles were prepared by mechanical alloying method.After being activated by positive potential cyclic voltammetry,floc structure grew on the surface of nanoparticles,which was a mixture of amorphous metal hydroxyl oxides.In the OER catalytic characterization,the overpotentials of Fe Co Ni Cr P and Fe Co Ni Mn P were 301m V and 330m V,respectively,and the Tafel slopes were 55.3m V dec^-1 and 90.3m V dec^-1.After activation,the overpotentials of Fe Co Ni Cr P and Fe Co Ni Mn P reduced to 286m V and 316m V,and the Tafel slopes reduced to 47.2m V dec^-1 and 86.2m V dec^-1.Surface with floc structure could provide more reactive sites,increase the electrochemical activity area of the catalyst,promote charge generation and transfer rate,thereby improved the OER catalytic activity of nanoparticles.