High Performance Bimetal Electrocatalysts Derived From FeNi-MOFs And ZnCo-ZIFs Towards Oxygen Evolution Reaction

Hydrogen,as high gravimetric energy carrier and clean energy,can be currently generated by steam reformation or partial oxidation of hydrocarbon.However,the increasingly serious energy crisis and environmental pollution have triggered an aggressive search for renewable and environmentally friendly alternative energy resoures.Water electrolysis is one of the promising and appealing pathways to obtain hydrogen,where it can produce oxygen and hydrogen to realize conversion between electricity and chemical energy.However,oxygen evolution reaction（OER）usually proceeds via four-electron transfer with slower kinetics in water splitting and the significant electrode polarization effects,which makes the high overpotential and high consumption of electrical energy.As a result,many studies have focused on efficient,economical,and earth-abundant catalysts in OER.Metal-organic frameworks（MOFs）formed by connecting metal nodes with organic units have been intensively employed as an emerging class of precursors/templates to construct nanostructures with unique architectures.Nevertheless,the use of multi-compositional synergism derived from MOFs for electrocatalytic OER is still in its infancy.The main research results are as following:（1）An effective and facile template-engaged strategy originated from bimetal MOFs is developed to construct hollow microcubes assembled by interconnected nanopolyhedron,consisting of intimately dominant FeNi alloys coupled with a small NiFe₂O₄ oxide,which was confined within carbonitride outer shell（denoted as FeNi/NiFe₂O₄@NC）viaone-stepannealingtreatment.Theoptimized FeNi/NiFe₂O₄@NC exhibits excellent electrocatalytic performances toward OER in alkaline media,showing 10 mA cm^-2 atη=316 mV,lower Tafel slope(60 mV dec^-1),and excellent durability without decay after 5000 CV cycles,which also surpasses the IrO₂ catalyst and most of non-noble catalysts in the OER,demonstrating a great perspective.The superior OER performance is ascribed to the hollow interior for fast mass transport,in situ formed strong coupling between FeNi alloys and NiFe₂O₄ for electron transfer,and the protection of carbonitride layers for long stability.（2）Dodecahedral ZnCo-ZIFs is successfully synthesized with a facile solvothermal method by controlling the molar ratio of cobalt ion and zinc ion in reactant.After carbonization,ZnCo-ZIFs can be transformed into ZnCo₂O₄/Co₃O₄@NC and preserve rhombicdodecahedronstructure.Inelectrochemicalwatersplitting,ZnCo₂O₄/Co₃O₄@NC shows superior OER performance with a low overpotential（350mV）for a current density of 10 mA cm^-2 and a low Tafel slope(88 mV dec^-1).Chronoamperometry manifests its excellent durability.The superior OER performance should be relevant with the high content of trivalent Co and the protection of carbonitride layers.