Controllable Synthesis And Electrocatalysis Oxygen Evolution Reaction Performance Of CoFe₂Se₄/NiCo₂Se₄ Hybrid Nanotubes With Heterointerfaces

The escalating dependence on fossil fuels has caused fast accumulation of CO₂ in the atmosphere and world-wide environmental crises over recent years.The development of new renewable energy sources is therefore an effective way of tackling the energy and environmental crisis.As hydrogen is extremely friendly to the environment,hydrogen energy will become the most promising renewable energy source.The production of hydrogen by electrolysis of water has therefore received a lot of attention.However,the large overpotential required for the four-electron anode oxygen evolution reaction(OER),which results in a low energy conversion efficiency for electrolytic hydrogen production,is the biggest obstacle to achieving a hydrogen economy.In order to reduce the OER overpotential,it is essential to develop high performance OER electrocatalysts to enhance its slow reaction kinetics.Nanostructures with heterointerface have attracted great interest in energy storage and conversion due to the special physical/chemical properties caused by the often-cited interplay of charge,spin,orbital,and lattice degrees of freedom.A variety of effective strategies have been developed to construct heterointerfaces.But these strategies are usually used to prepare the metal/metal compound heterointerfaces.Among various promising electrode materials,transition metal selenides(e.g.,Fe-,Co-,and Ni-based selenides)have attracted more and more attention due to their good electrical conductivity.In comparison with single-metal selenides,bimetallic selenides exhibit enhanced electrochemical performances with wide applications in the field of super-capacitors,oxygen-evolution reaction,Li-S batteries and Na ion batteries.However,because each component possesses different physicochemical properties and lattice structure,the controllable synthesis of bimetallic selenide/bimetallic selenide with heterointerface remains a great challenge.In this study,we demonstrate the synthesis of CoFe₂Se₄/NiCo₂Se₄ hybrid nanotubes(CoFe₂Se₄/NiCo₂Se₄ HNTs)with open ends and abundant heterointerfaces.The CoFe₂Se₄/NiCo₂Se₄ HNTs hybrid nanotubes are obtained by using NiCo₂-aspartic acid nanofibres(NiCo₂-Asp NFs)as the templates which can be converted to the CoFe₂Se₄/NiCo₂Se₄HNTs via proton etching,three metal coprecipitation,Kirkendall effect and anion-exchange reaction.The CoFe₂Se₄/NiCo₂Se₄ HNTs may function as the oxygen evolution reaction(OER)electrocatalysts,and exhibit a low overpotential of 224 mV at the current density of 10 mA/cm²and outstanding stability with only 1.4%current density change even after 15 h,superior to the reported single-component counterparts.The calculations of density of states and differential charge density confirms the existence of heterointerface which can induce the accumulation of electrons at the interface of CoFe₂Se₄-NiCo₂Se₄ and consequently increases the carrier density and the electrical conductivity of the CoFe₂Se₄/NiCo₂Se₄ HNTs.This research provides a new avenue for the fabrication of hollow nanohybrids with heterointerfaces.