In Situ Preparation And Property Research Of Co/Ni Oxide/Suldide Nanomaterial Based On 3D Network

Transition metal oxides/sulfides are widely used in electrochemical energy storage and environmental catalysis due to their abundant reserves,variable valence state,low-cost,safe,and other advantages.Therefore,it is very important to prepare composite materials with good electrical conductivity and structural stability by constructing composite heterostructure and exerting the synergistic effect of multi-components.In this paper,the transition metal cobalt-based and copper-based oxygen/sulfur compounds were taken as the research objects,and graded heterogenous structures based on these materials were constructed on three-dimensional skeleton materials using in-situ growth method.By studying the relationship between the structure,components and properties of the materials,the controllable preparation and performance improvement of cobalt-based and copper-based nanomaterials were realized.Firstly,hierarchical lily-like Co₃O₄ nanostructures assembled from 1 D nanowires were in situ synthesized on Ni foam with a 3 D network.The prepared Co₃O₄/Ni was used as electrode material for supercapacitor,and exhibited excellent rate capability and cycling performance,which showed a specific capacitance of 1600F/g even at a relatively high 10 A/g current density that barely declined after 5000cycles.In two-electrode mode,the assembled asymmetric supercapacitor device showed a high specific capacitance at a high current density?108.1 F/g at a current density of 0.5 A/g,96.4 F/g at 10 A/g and 77.9 F/g even at 50 A/g?and displayed a long-term cycling stability performance?10 000 cycles?with a high energy density?34 Wh/kg?at a high power density of 1963 W/kg.Its excellent electrochemical performance is attributed to the close combination of 1 D nanowires and Ni foam,with improved electrical conductivity and cycling stability of this material.Secondly,based on Ni foam,a stepwise in situ method was introduced to prepare Co₃O₄@C@MnO₂ heterostructures as binder-free supercapacitor electrode material,in this structure,Co₃O₄ acts as“core”,MnO₂ acts as“shell”.In three-electrode mode,Co₃O₄@C@MnO₂ shows a high cyclic specific capacitance of 1335.3 F/g at a current density of 20 A/g.In two-electrode mode,the asymmetry supercapacitor device exhibits high specific capacity?126.6 F/g at a current density of 0.5 A/g?and long life?about 61 F/g at a relatively high current of 20 A/g after 40,000 cycles?.Compared with Co₃O₄@MnO₂ or C@MnO₂,the improved performance of Co₃O₄@C@MnO₂ is proposed to be attributed to the synergistic effect in multi-components heterostructures.Thirdly,flexible PAN-CuS hierarchical heterostructures were in situ synthesized through a facile in situ hydrothermal sulfuration growth process on PAN-based fibers prepared by electrospinning.The PAN fibers with a 3 D network structure can serve as a stable flexible support,while CuS flowers assembled from nanosheets can act as reactive materials.This PAN-CuS hierarchical heterostructures were used to degrade organic dyes under ultraviolet light,the results show this material possess high performance in the degradation of dyes and favorable recycling capability.It is attributed to these heterostructures are effective for suppression of electron–hole recombination,and can be recovered easily without a decrease in their photocatalytic activity.