Preparation And Electrochemical Performance Of Supported Nickel-iron-phosphorus-based Composite Electrocatalysts

Since the policy of"carbon peak and carbon neutrality"was proposed,energy conservation and emission reduction have become the consensus of all mankind.The development of green energy technology is very important to reduce carbon dioxide emission,and the preparation technology of green hydrogen plays an important role in green energy.The electrochemical kinetics is controlled by oxygen evolution reaction（OER）and hydrogen evolution reaction（HER）respectively.The theoretical decomposition voltage of electrolytic water is 1.23 V.However,in the actual electrolytic cell,due to the slower kinetic steps of HER and OER,higher energy supply is required.The cost of hydrogen production can be significantly reduced by developing a variety of high activity electrolytic water catalysts to reduce the activation energy of the reaction.In this paper,two kinds of supported electrocatalysts Ni-Fe-P-WO₃/NF and Ni-Fe-P-Ni（OH）₂/NF were prepared by chemical composite plating method.The effects of the composition,morphology,phase structure and surface composition of the catalysts on the electrocatalytic properties were studied,and the catalytic mechanism of the electrocatalysts was preliminatively discussed.The main contents of the paper are as follows:1.Ni-Fe-P-WO₃/NF composite electrocatalysts with different content of WO₃ were prepared.The effects of deposition temperature,time and p H of the plating solution on the electrode structure and properties were studied.By constructing heterogeneous interfaces,the Ni-Fe-P-WO₃/NF catalyst can have more abundant effective active sites,and the WO₃ nanosheet can produce synergistic effect with Ni Fe,thus showing excellent OER catalytic activity.The results show that the heterogeneous Ni-Fe-P-WO₃/NF catalyst exhibited excellent OER performance in 1 M KOH electrolyte,and the current density of 10 m A cm^-2 can be reached with an overpotential of only 218 m V,the Tafel slope is 42 m V dec^-1.The Ni-Fe-P-WO₃/NF composite catalyst has contributed to the construction of excellent oxygen evolution electrocatalysts.2.Overall water splitting catalyst has relatively fast hydrogen and oxygen evolution reaction kinetics.According to this requirement,the heterogeneous supported Ni-Fe-P-Ni（OH）₂/NF composite electrocatalyst is prepared,which shows excellent total water splitting performance and durability stability.Ni（OH）₂ has excellent alkaline hydrogen evolution properties,and the electronic structure of the alloy can be optimized by adding P into Ni Fe material.By chemical composite plating,Ni（OH）₂ and Ni-Fe-P alloys are combined to construct heterogeneous interfaces.The bifunctional electrocatalytic activity of Ni-Fe-P-Ni（OH）₂/NF at the current density of 10 m A cm^-2 was superior.The overpotentials wereη_HER=112.6 m V,η_OER=245 m V,respectively.Ni-Fe-P-Ni（OH）₂/NF||Ni-Fe-P-Ni（OH）₂/NF electrolyzer voltage was 1.51 V,the Tafel slopes of HER and OER were 85.4 m V dec^-1 and 53.1 m V dec^-1,respectively.The results of chronopotentiometry showed that Ni-Fe-P-Ni（OH）₂/NF electrode had good stability in HER,OER and OWS.This study provides a new idea for the synthesis of simple and high activity full hydrolysis catalyst.In short,the two kinds of composite electrocatalysts Ni-Fe-P-WO₃/NF and Ni-Fe-P-Ni（OH）₂/NF constructed in this paper both have catalytic activity comparable to that of noble metal catalysts and remain stable after long reaction,which provides new insights for the future development of transition metal-based catalysts.