Design, Preparation And Electrocatalytic Performance Of Carbon-supported NiFe Bimetallic Catalysts

Hydrogen energy is extensively regarded as one of the most ideal energy due to its zero-carbon emission,high energy conversion efficiency and environmental friendliness.Water splitting which can produce high-purity hydrogen is considered as one of the effective ways to alleviate energy crisis and environmental pollution.Electrolysis of water makes up of the cathodic hydrogen evolution reaction(HER)and the anodic oxygen evolution reaction(OER).Compared to HER,OER is limited by the slow reaction kinetics and large overpotential because of this process involves four electrons which make this process.Up to now,the most effective OER catalysts still depend on noble metal oxides,such as RuO₂ and IrO₂.However,their scarcity and high price as well as poor long-term stability greatly limit their large-scale application.Therefore,it is extremely necessary to design and develop low-cost alternative catalysts with high activity and durability to replace precious metal catalyst.Transition metal catalysts have been reported as attractive electrocatalysts for OER owing to their cost-effectiveness,unique electronic structure and high catalytic activity.Herein,we successfully prepare low-cost catalysts with high activity through a simple and environmental method,which show great application prospect in water splitting.The specific research contents of this paper are as follows:1.In this work,a simple and facile catalyst synthesis strategy has been designed to in-situ form Ni_xFe_yS/C with sulfonic resin as both a carbon and sulfur source.And their crystal structure strongly depends on the additive amount of Fe species.Ni₃S₂ and Ni phase are dominated in the sample Ni_xFe₀S/C,however,after adding iron,Fe-doped Ni₃S₂ and Ni₃Fe,and Fe S were obtained according to different Ni/Fe ratio.Catalyst Ni₉Fe₄S/C,a uniform composite of Ni₃S₂ and Ni₃Fe on carbon with high dispersity,low crystallinity and narrow size distribution(12-22 nm),shows the best electrocatalytic activity for oxygen evolution reaction(OER),i.e.,the current density of 10 m A·cm^-2at the overpotential of?323 m V in 0.1 M KOH and?183 m V in 1 M KOH.Therefore,the simple synthetic method makes it a general one for the industrial production of M_xS_y/C catalyst derived from sulfonic resin without additional S source,and highly active Ni_xFe_yS/C products would be expected to be applied for the water splitting in the future.2.Based on the defect of poor conductivity of metal alloy catalyst,an economical and green synthesis method was designed in this paper.Using cellulose fiber as raw material,the surface of cellulose fiber has rich oxygen-containing functional groups and hydrophilic characteristics,through ion exchange method to absorb a large number of metal ions,and then through high temperature roasting successfully prepared carbon fiber supported metal particles catalyst.By adjusting the calcination temperature and the concentration of the total NiFe metal content in the precursor solution,the metal load and the size of the metal particles in the catalyst can be controlled,thus affecting the catalytic performance of the catalyst in the catalytic reaction process.When the calcination temperature was 800?and the total NiFe metal concentration was 0.15mol·L^-1,the catalytic activity of the catalyst reached the best.When the current density was 10 m A·cm^-2 in 1 M KOH solution,the over-potential of the catalyst was 233 m V.The activity of the catalyst remained unchanged after 9 h stability test.