Design Of Transition Metal Oxides Hollow Structure And Phosphide Yolk/Shell Architecture And Study Of High Efficient Energy Storage

It is always a concerned topic for human to develop and study energy,especially reproducible clean energy.We successfully prepared Co₃O₄@Al₂O₃ nanosheets composite and graphitized carbon@Fe₂P yolk/shell octahedrons composite（Fe₂P/GC）via hydrothermal method and followed by calcination using tube furnace and（or）muffle.And a series of test instruments was taken to analyze the morphology and elements,and to evaluate the chemical performance.The two samples exhibit well in lithium ion batteries（LIBs）and hydrogen evolution reaction（HER）,respectively.Because the precursors synthesized by hydrothermal method acted as the template,the two products after the calcination inherited the morphology character of the relevant precursors.Thus,the as-prepared samples possess novel architecture and excellent property.The main points of this work is generalized as follows:Firstly,we prepared the precursor Co₆Al₂CO₃（OH）16.4H2 O nanosheets crystal by hydrothermal method as template.Followed by reduction through tube furnace,the precursor converted into Co@Al₂O₃ nanosheets composite,which means the Co₆Al₂CO₃（OH）16.4H2 O crystal was reduced to elemental Co nanoparticals encapsulated by Al₂O₃ nanosheets.Then,the Co nanoparticals was oxidized into Co₃O₄ hollow nanospheres by muffle,which were still encapsulated by Al₂O₃ nanosheets and inherited the hexagonal nanosheet morphology of precursor.The inactive Al₂O₃ nanosheets acted as the braced frame of the active Co₃O₄ hollow nanospheres,which makes the materials structure more strong.Owing to the innovative and uniform architecture,the as-synthesized composites big possesss specific surface area（SSA）and superior chemical property.While assembled the materials as LIBs,the reversible capacity of Co₃O₄@Al₂O₃ nanosheets composite is 1278 mAh/g at the current density of 0.1 A/g,and the coulombic efficiency is nearly 99%.Therefore,the as-prepared nanosheets composite reveal high reversible capacity and durable cycling stability,which has good prospect in the application of LIBs.Besides,we synthesized octahedral graphitized carbon shells with Fe₂ P particles covered inside.Firstly,the precursor and template is Fe₂PO5 octahedrons crystal covered by polymer layer（Fe₂PO5/C）prepared through hydrothermal method,followed by reduction reaction through tube furnace,then the precursor converted into Fe₂ P particles with octahedral graphitized carbon shell outside（Fe₂P/GC yolk/shell octahedrons）.Such yolk/shell architecture can make the active materials become homodisperse,which may restrain the aggregation and volume expansion of the as-synthesized composites during the chemical reaction.As the HER catalyst,Fe₂P/GC yolk/shell octahedrons exhibit remarkable catalytic activity.The overpotential requirement to obtain 10 mA cm-2 current density is 76 mV.The as-prepared composite has also been applied in LIBs as anode.The electrochemical test exhibits a steady specific capacity of ⁶27 mA h/g and nearly 100% coulombic efficiency at a current density of 0.1 A/g.Therefore,Fe₂P/GC yolk/shell composite is a promising anode in LIBs as well as catalyst in HER.