The Preparation Of Cobalt Oxide One-dimensional Nano Structure And Their Electrocatalytic Activity In Oxygen Evolution Reaction

Hydrogen,with its high mass-specific energy density,has been considered to be a promising energy source and a substitute for fossil fuels.One of the most efficient ways of producing H2 at low cost and high purity is water splitting into hydrogen and oxygen by electricity.The water-splitting reaction can be classified into two half reactions: the oxygen evolution reaction?OER?and the hydrogen evolution reaction?HER?,both of which are vital for the overall efficiency of water splitting.The OER involves a fourelectron transfer process and has sluggish oxygen evolution kinetics,which significantly impeded the overall efficiency of the process,and hampered the possibility of hydrogen production from water splitting on an industrial scale.Therefore the development of effective and stable OER electrocatalyst is urgently required in order to promote the evolution kinetics and improve the energy-conversion efficiency.To date,Iridium dioxide?Ir O₂?and ruthenium dioxide?RuO₂?are the state-of-theart OER electrocatalysts with low overpotential and Tafel slope.Nevertheless,their widespread commercial applications are restricted significantly because of their low abundance and high cost.Accordingly,in order to replace these expensive catalysts,extensive efforts have been devoted to the design,synthesis,and characterization of alternative OER electrocatalysts based on transition-metal elements that are low cost,highly active,and stable long-term.Co-based OER catalysts have emerged as a promising candidate for investigating the water oxidation reaction by electrocatalytic processes in an alkaline mediumIn this paper,these novel structure and excellent performance catalysts cobalt oxide Nanowires?Co₃O₄ NW?and porous core-shell multistage structure cobalt oxide?CoO_x-PHCS?were synthesized from containing transition metal Co-based precursors aqueous by commonplace materials fabricating methods.Moreover its morphology and performance of oxygen evolution were studied,the main results are as follows:?1?In this work,Carbon fiber paper?CFP?was used as the conductive substrate.Co₃O₄ nanowires loaded on CFP were prepared by hydrothermal method and air annealing.The as-synthesized Co₃O₄ nanowires show an excellent catalytic activity with low onset overpotential?1.52 V vs.RHE?and a small overpotential of 330 mV at the current density of 10 mAcm-2 with a Tafel slope of 60 mV dec-1.In addition,the Co₃O₄ nanowires can maintain its high electrocatalytic activity at least 24 h in alkaline medium.The enhanced performance of CFP-Co₃O₄ nanowires can be attributed to three aspects: the high conductivity of CFP,the rough surface structure and the tight connection between Co₃O₄ NW and carbon.?2?Introduces a preparation method of the porous hierarchical structure catalyst CoO_x-PHCS and its better OER performance.First transferred the cobalt-based nanowires that grown by hydrothermal into CoS2 nanowire,and then the Co?OH?2 nanosheets were deposited on the surface of nanowire to form a core-shell hierarchical structure,at last the porous hierarchical structure CoO_x-PHCS was prepared by electrochemical activation.CoO_x-PHCS show a small overpotential 300 mV at the current density 100 mA cm-2,the Tafel slope was only 40 mV dec-1.The performance is superior to commercial RuO₂ electrocatalyst and other reported non-precious metal OER electrocatalysts.The CoO_x-PHCS maintains large and stable current density in 40 h,and the faradaic efficiency of the CoO_x-PHCS is 96%.