Synthesis Of Cobalt-based,Iron-based Nanomaterials And Their Application In Electrocatalytic Oxygen Evolution Reaction

Electrocatalytic water splitting is considered to be one of the most promising green and sustainable technologies for hydrogen production.However,the wide application of electrocatalytic water splitting suffers from the sluggish kinetics of oxygen evolution reaction?OER?at the anode.Therefore,it is of great significance to develop transition-metal-based catalysts with low cost,high activity and favorable stability to accelerate the OER rate.In order to study the performance of transition-metal-based nanomaterials in electrocatalytic OER,this work focuses on synthesizing cobalt-based and iron-based nanomaterials,and their electrocatalytic performance were optimized by the strategies of materials hybridization,substrate auxiliary and morphology control.The main research contents are summarized briefly as follows:1.Engineering Strongly Coupled Interface Structure in CoFe LDH/Co₃O₄Nanohybrids as Highly Efficient Oxygen Evolution Reaction CatalystsAs an important representative of cobalt-based oxides,Co₃O₄ nanocrystals have attracted much attention due to the merits of low price and corrosion stability.However,the activity of Co₃O₄ is far away from the satisfaction in practical demand,so the effective strategies should be adopted to improve the catalytic activity of Co₃O₄.In this work,Co3O4 was used as the active substrate,the CoFe LDH nanosheets directly grew on the surface of Co₃O₄ with the ultrasonication assistance,and the CoFe LDH/Co₃O₄nanohybrids were prepared.By optimizing the annealing temperature of Co₃O₄substrate and adjusting the molar ratio between CoFe LDH and Co₃O₄,the optimal CoFe LDH/Co₃O₄?6:4?nanohybrid with excellent activity and favorable stability was obtained.Physicochemical characterizations and electrochemical tests demonstrated that the synergistic effect induced by the strongly coupled interface endowed the CoFe LDH/Co₃O₄?6:4?nanohybrid with excellent catalytic performance.2.Vertically Aligned FeOOH Nanosheet Arrays on Alkali-treated Nickel Foam as Highly Efficient Electrocatalyst for Oxygen Evolution ReactionAs an important representative of iron-based electrocatalysts,FeOOH is favored for its high intrinsic activity,low cost and environmental friendliness.However,the electrocatalytic OER performance of FeOOH suffers from the poor electrical conductivity.In this work,the alkali-treated nickel foam was used as the conductive substrate,the FeOOH nanosheet arrays were loaded on the substrate by a hydrothermal method.By optimizing the NH₄F-additive quantity and solvent composition during the hydrothermal reaction process,FeOOH NSAs/ATNF exhibited excellent activity and durable stability toward OER.The outstanding performance of FeOOH NSAs/ATNF were attributed to:?i?the nickel foam substrate greatly improved the electrical conductivity of the catalyst;?ii?the unique nanosheet arrays structure was conducive to charge transfer and mass transport,and made more potential active sites work efficiently;and?iii?the synergistic effect between FeOOH and ATNF can facilitate OER kinetics,and improved the catalytic activity and stability of the catalyst.