Orderly Structured Metal Oxides:Fabricated And Their Eletrochemical Performance

As a new generation of energy storage device, supercapacitor has been intensively applied in many fields. Therefore, the research about the electrode materials of the core of supercapacitors appears increasingly important. Typical transition metal oxides, such as Co3O4, NiO, NiCo2O4, MnO2and ZnCo2O4were widely studied and applied in the field of optical, electrical and magnetic. In this paper, the controllable preparation of transition metal oxides can be reached by various strategies including hydrothermal treatment, in-situ growth and anodic oxidation, the reaction mechanisms and properties in supercapacitors, non-enzymatic glucose sensors and photocatalysts are investigated. The main results are as follows:(1) Hierarchical mesoporous conch-like Co3O4nanostructure arrays with the thickness of a few nanometers supported on Ni foam substrate have been fabricated by a hydrothermal approach together with a post-annealing treatment. The highly ordered three-dimensional (3D) nanostructure offers numerous advantages due to the desired properties of macroporosity, including enhanced mass transport for the electrolyte flow, thereby reducing the device resistance and faster the reaction kinetics. Such unique nanoarchitecture exhibits remarkable electrochemical performance with high capacitance and desirable cycle life as an electrode material for supercapacitors.(2) Ultrathin Co3O4nanosheets with a mesoporous structure and a large surface area are hydrothermally grown on a three dimensional nickel foam. The ultrathin mesoporous Co3O4nanosheets are grown on Ni foam with robust adhesion, which endows fast ion and electron transport, large electroactive surface area, and excellent structural stability. When evaluate as an electrode material for supercapacitors, the Co3O4nanosheets electrode is able to deliver high specific capacitance of2194F g-1at a current density of I A g-1in1M KOH aqueous solution. The electrode also exhibits excellent cycling stability by retaining93.1%of the maximum capacitance after5000charge-discharge cycles.(3) A novel3D core-shell Co3O4@MnO2nanoconch arrays were fabricated by a facile, stepwise hydrothermal approach. Core-shell Co3O4@MnO2nanoconches were directly grown on a Ni current collector as an integrated electrode/collector. It has shown excellent electrochemical performances when it is used for supercapacitor, such as high specific capacitances1183.7F g-1at a current density of I A g-1and long-term cycling stability (-92.5%of capacitance retention up3000cycles at1A g-1), which are better than that of the individual component of Co3O4nanoconch arrays and MnO2nanosheet arrays.(4) ZnCo2O4/MnO2nanocone forests with a mesoporous, hierarchical core-shell structure and a large surface area were hydrothermally grown on3D nickel foam. The supercapacitor electrodes prepared from the unique structure exhibits exceptional specific capacitances of2339and1526F g-1at current densities of1and10A g-1, respectively, and long-term capacity retention of-95.9%after3000cycles at2A g-1and94.5%after8000cycles at10A g-1.