Electrodeposition Of Nickel-iron Alloy And Its Catalytic Performance For Oxygen Evolution Reaction

Hydrogen,one of the green energy resources,has stood out as a leading candidate by virtue of its high combustion heat value and high reserves.Amongst routes towards the production of Hydrogen,electrochemical water splitting is the most promising approaches to the cost-effective carbon-free production of hydrogen with easy equipment and operations.However,high consumption of energy and low efficiency stands in the way of the development of electrolysis of water.Moreover,as a half reaction of water splitting,the oxygen evolution reaction（OER）is more sluggish and has higher energy barrier.Therefore,developing efficient electrocatalysts towards water oxidation has attracted overwhelming solicitude and tremendous research interests.Noble metals Ru,Ir and their oxides RuO₂and IrO₂ have been widely used as industrial catalysts for OER,yet the earth-scarce precious metals and high cost stand in the way of its large-scale production.In order to further reduce the costs and accelerate OER,it’s of great importance to develop alternative and inexpensive OER electrocatalysts.Transition metals have been used as electrocatalysts for OER in alkaline electrolytes for their special electronic structure and surface properties,especially nickel-iron bimetallic catalysts.The catalytic properties depend,on the one hand,on their compositions and intrinsic activity,and on the other hand,on the number of their active site and specific surface area.To this end,in this paper,nickel-iron alloy with high catalytic performance was prepared by a simple electrodeposition method,and its deposition conditions and catalytic properties were regulated and optimized.The specific research contents are as follows:1.Nickel-iron alloy was deposited on the copper plate by constant current deposition method.The deposition conditions such as pH,current density and temperature were controlled to prepare flakes,needles,cones,stars and granules-like Ni-Fe alloys.The evaluation of its electrocatalytic performance towards OER shows that the Ni-Fe alloy deposited at current density of 4 ASD and pH of 3.5 exhibits highest intrinsic catalytic activity with a Ni Fe ratio of 55:45.And also,due to its large specific surface area,high roughness,and a large number of active sites of the needle-like structure,the overpotential for OER has been decreased by as-deposited Ni-Fe alloy.2.Preparation of three-dimensional NiFe/NF electrode and its electrocatalytic performance towards OERNickel-iron alloy was prepared on the three-dimensional skeleton of nickel foam by potentiostatic deposition.This paper gives insights into its morphology,composition,structure,electrocatalytic performance and reaction mechanism.The the catalytic active phase in the nickel-iron alloy is NiOOH,and the nickel foam substrate enhances the conductivity and provides support for the catalytically active component.Moreover,nickel and iron have a synergistic effect.By altering the deposition potential,the bath composition and the substrates,it was observed that the NiFe/NF deposited at-1.0 V exhibits high OER efficiency with a low overpotential of 191 mV at 10 mA cm^-2,which outperforms the commercial catalyst and most reported catalysts up-to-date.Also,it shows a remarkably low Tafel slope of 44.1 mV dec^-11 as well as a long-time stability that the potential increased less than 10 mV after 30000 s OER at 100 mA cm^-2.NiFe/NF is expected to surpass the commercial catalyst to serve as a non-noble-metal-based electrocatalyst for OER practical application.