Preparation And Electrochemical Performance Of Supported Nickel-Iron-Based Composites

It is urgent to solve a series of problems caused by the depletion and utilization of fossil energy.Hydrogen is considered as a promising green energy carrier in the future.Using renewable energy to generate electricity for electrocatalytic hydrogen production is the crucial step to build an energy system with hydrogen as the core.Currently,the main problem of electrocatalytic hydrogen production to be solved is the preparation of non-noble metal based electrocatalyst and the improvement of its electrocatalytic performance.In this paper,two types of NiFe based composite materials were designed and prepared,and their structures and electrochemical properties were systematically characterized.The main contents of this paper are as follows:The first work of this paper constructed layer-by-layer alternately stacked Ni–Fe–P and Co–P films supported on nickel foam with the help of autocatalytic reactions of electroless.The dispersed growth of the alloy films was induced by dealloying processes,which result in the multilayer films with different morphologies;The multilayer alloy films reduce the resistance of charge and transport,shorten the distance of ion transport,and improve the ability of electron transport and mass transfer;The amorphous structure of multilayer films has an enormous number of unsaturated coordination sites which provide abundant reaction sites for electrocatalytic hydrogen evolution;The interface engineering between the two alloy films improves the reaction kinetics of the composite films;The electronic interaction between Ni-Fe-P alloy and Co-P alloy promotes the catalytic activity of the composite films;The self-supported multilayer Co-P/Ni-Fe-P films electrode shows excellent catalytic performance in electrocatalytic hydrogen evolution.In the second work of this paper constructed a home-made two-electrode system with extensibility based on the working principle of electroplating.NiFe Mo composite film on the nickel foam substrate was prepared by simple one-step electrodeposition,which can act as cathode and anode material of urea electrolyzer for hydrogen production and purification of urea containing wastewater.It was found that NiFe Mo composite was composed of Fe doped Nickel Hydroxide and amorphous NiFe composite containing Mo doped phasel;There are numerous lattice distortion,low coordination steps,edges,dangling bonds and microcrystalline,mixed crystal and amorphous components with unsaturated coordination structure in NiFe Mo composite films,which provide abundant sites for catalytic reaction;The introduction of Mo into NiFe composite induces the charge redistribution among the components of the material,and boosts the synergistic effect among the three metals,thus promoting the formation of nickel iron hydroxide;The appropriate composition ratio of Mo and Ni can adjust the bonding strength of the composite to hydrogen,which promotes the hydrogen evolution reaction;The self-supported NiFe Fo composite film with outstanding performance can not only act as cathode and anode of electrolytic water,also be used in electrolytic urea to produce hydrogen and purify urea containing wastewater,which achieved the purpose of both energy production and environmental restoration.The above two methods for preparing self-supported NiFe based composite catalysts have a series of merits,such as simple and controllable process,cheap raw materials,stable and reliable performance which is hopeful to replace the rare precious metal catalysts to realize large-scale production and apply in electrocatalytic hydrogen production.