Fabrication Of Ni-based Highly Active Material By Electroetching And Its Electrocatalytic Oxidation Performance

Hydrogen is considered the most promising clean energy alternative to fossil fuels due to its zero-carbon content and highest energy density.Hydrogen can be obtained from a wide range of sources,including natural gas,other fossil fuels and electrolytic water.Among them,the preparation of hydrogen by electrolytic water without producing other pollutants is a very promising,environmental protection and green renewable energy conversion strategy.However,the oxygen evolution reaction(OER)involves multiple electron transfer steps and the formation of oxygen-oxygen bond,which is considered to be the main bottleneck of hydrogen production by electrolysis of water.Therefore,the design of efficient electrooxidation catalysts to reduce overpotential is of great significance to achieve efficient hydrogen production and"carbon neutrality".Ni-Fe layered double hydroxides(NiFe-LDH)is an excellent electrocatalyst,and its electrocatalytic performance can be further improved by adjusting its microstructure.Based on this,the research content and results of this work are as follows:Ni(Fe)OOH has been considered the most active intermediate in electrochemical oxygen evolution reaction,however,it is difficult to directly synthesize because of high oxidation energy and unstable properties.Here,multicomponent active electrocatalyst Ni(Fe)OOH is fabricated by the simple bidirectional diffusion,self-reconstruction strategy for alkaline oxygen evolution reaction.A series of HR-TEM,Raman and XPS characterizations show that the crystalline phase and amorphous phase coexist in Ni(Fe)OOH,and there is an obvious phase interface.Both Ni and Fe in Ni(Fe)OOH present a+3 valence state,Ni(Fe)OOH has abundant oxygen vacancy and pore structure.Ni(Fe)OOH exhibits superior performance with a low overpotential of 175m V at the current density of 10 m A/cm~2 and a small Tafel slope of 35.89 m V/dec,which is comparable to the most excellent non-noble catalysts.Moreover,Ni(Fe)OOH catalyst exhibits excellent OER stability in alkaline electrolytes,and doesn’t change significantly after 72 h of testing.The crystalline phase in Ni(Fe)OOH provides good electron transport capacity;The long distance disordered amorphous phase structure is more conducive to promoting the adsorption of intermediates because of the relatively random bond length,sufficient oxygen vacancy,high active site and unsaturated electron configuration.The coexistence of crystalline and amorphous phases in Ni(Fe)OOH is an effective method to obtain high OER activity while maintaining material stability.The defective NiFe-LDH laminate can provide special limiting sites for anchoring precious metals,and is the preferred strategy for coupling precious metals.On the basis of the previous work,the accurate filling of Pt nanoparticles on the pores of defective NiFe-LDH nanosheets was achieved by means of electroreduction deposition through the defect recovery strategy to construct V-HCNF@NiFe-LDH-Pt catalyst.5-hydroxymethylfurfural electrooxidation(HMFOR),which is thermodynamically more favorable than OER and can produce high value-added fine chemicals,was studied as a probe reaction.V-HCNF@NiFe-LDH-Pt as HMFOR catalyst can effectively reduce overpotential(lower than OER potential).HMF conversion,the yield of FDCA and Faraday efficiency are 99.5%,97.9%and 97.4%,respectively.There is no significant change in HMF conversion,the yield of FDCA and Faraday efficiency during six cycles.Therefore,it is expected to be coupled with hydrogen evolution reaction to improve overall energy efficiency and increase economic benefits.The results provide a new idea for the design of Pt supported NiFe-LDH catalyst.