Jinbing Cheng

Mesoporous CuCo2O4 nanograsses as multi-functional electrodes for supercapacitors and electro-catalysts

Hierarchical, mesoporous CuCo2O4 nanograsses have been synthesized on copper foam using a simple and cost-effective hydrothermal approach followed by a post-annealing treatment. The electrodes made from the novel nanoarchitecture exhibit multi-functional electrochemical performance. They deliver an excellent specific capacitance of 796 F g−1 at a current density of 2 A g−1 in a 2 M KOH aqueous solution and a long-term cyclic stability of 94.7% capacitance retention after 5000 cycles. When applied to electro-catalytic oxidation of methanol, the current density of the CuCo2O4/Cu foam electrode in 1 M KOH mixed with 0.5 M methanol is maintained up to 27.6 A g−1. The superior electrochemical performances are mainly due to the unique one dimensional porous acicular architecture with a very large surface area and porosity grown on a highly conductive Cu substrate, offering faster ion/electron transfer, an improved reactivity and an enhanced structural stability. The fabrication strategy presented here is simple, cost-effective and scalable, which can open new avenues for large-scale applications of the novel materials in energy storage.

Hierarchical Core/Shell NiCo2O4@NiCo2O4 Nanocactus Arrays with Dual-functionalities for High Performance Supercapacitors and Li-ion Batteries

We report the synthesis of three dimensional (3D) NiCo2O4@NiCo2O4 nanocactus arrays grown directly on a Ni current collector using a facile solution method followed by electrodeposition. They possess a unique 3D hierarchical core-shell structure with large surface area and dual-functionalities that can serve as electrodes for both supercapacitors (SCs) and lithium-ion batteries (LIBs). As the SC electrode, they deliver a remarkable specific capacitance of 1264 F g−1 at a current density of 2 A g−1 and ~93.4% of capacitance retention after 5000 cycles at 2 A g−1. When used as the anode for LIBs, a high reversible capacity of 925 mA h g−1 is achieved at a rate of 120 mA g−1 with excellent cyclic stability and rate capability. The ameliorating features of the NiCo2O4 core/shell structure grown directly on highly conductive Ni foam, such as hierarchical mesopores, numerous hairy needles and a large surface area, are responsible for the fast electron/ion transfer and large active sites which commonly contribute to the excellent electrochemical performance of both the SC and LIB electrodes.

Facile Synthesis of Graphene-Like Copper Oxide Nanofilms with Enhanced Electrochemical and Photocatalytic Properties in Energy and Environmental Applications

Novel graphene-like CuO nanofilms are grown on a copper foam substrate by in situ anodization for multifunctional applications as supercapacitor electrodes and photocatalysts for the degradation of dye pollutants. The as-prepared CuO consists of interconnected, highly crystalline, conductive CuO nanosheets with hierarchical open mesopores and a large surface area. The CuO nanofilms supported on a copper foam are employed as freestanding, binder-free electrodes for supercapacitors, which exhibit wonderful electrochemical performance with a large specific capacitance (919 F g(-1) at 1 A g(-1)), an excellent cycling stability (7% capacitance loss after 5000 cycles), and a good rate capability (748 F g(-1) at 30 A g(-1)). The porous CuO nanofilms also demonstrate excellent photocatalytic activities for degradation of methylene blue, with a degradation rate 99% much higher than 54% of the commercial CuO powders after 60 min. This excellent energy storage and photocatalytic performance of the graphene-like CuO nanofilms can open a new avenue for large-scale applications in energy and environmental fields.

Hierarchical, porous CuS microspheres integrated with carbon nanotubes for high-performance supercapacitors.

Carbon nanotubes (CNTs) incorporated porous 3-dimensional (3D) CuS microspheres have been successfully synthesized via a simple refluxing method assisted by PVP. The composites are composed of flower-shaped CuS secondary microspheres, which in turn are assembled with primary nanosheets of 15–30 nm in thickness and fully integrated with CNT. The composites possess a large specific surface area of 189.6 m2 g−1 and a high conductivity of 0.471 S cm−1. As electrode materials for supercapacitors, the nanocomposites show excellent cyclability and rate capability and deliver an average reversible capacitance as high as 1960 F g−1 at a current density of 10 mA cm−2 over 10000 cycles. The high electrochemical performance can be attributed to the synergistic effect of CNTs and the unique microstructure of CuS. The CNTs serve as not only a conductive agent to accelerate the transfer of electrons in the composites, but also as a buffer matrix to restrain the volume change and stabilize the electrode structure during the charge/discharge process. The porous structure of CuS also helps to stabilize the electrode structure and facilitates the transport for electrons.

Hierarchical porous CuO nanostructures with tunable properties for high performance supercapacitors

We report a novel, low-cost strategy to synthesize copper oxide (CuO) nanostructures as high-performance supercapacitor electrodes using an alkaline solution oxidation method. The structure, morphological features, surface area and pore size distribution of the products are tuned using different types of surfactants. The CuO electrode obtained from sodium dodecyl sulfate (SDS) presents the best electrochemical performance due to the synergies arising from the large surface area and pore volume created by the ultrathin nanoleaves constituting the flower-shape nanostructure. The electrode delivers a remarkable specific capacitance of 520 F g−1 at 1 A g−1 and a high rate capacitance of 405 F g−1 at 60 A g−1 with more than 95% Coulombic efficiency after 3500 cycles.

Ultrathin ZnS nanosheet/carbon nanotube hybrid electrode for high-performance flexible all-solid-state supercapacitor

Flexible and easily reconfigurable supercapacitors show great promise for application in wearable electronics. In this study, multiwall C nanotubes (CNTs) decorated with hierarchical ultrathin zinc sulfide (ZnS) nanosheets (ZnS@CNT) are synthesized via a facile method. The resulting ZnS@CNT electrode, which delivers a high specific capacitance of 347.3 F·g–1 and an excellent cycling stability, can function as a high-performance electrode for a flexible all-solid-state supercapacitor using a polymer gel electrolyte. Our device exhibits a remarkable specific capacitance of 159.6 F·g–1, a high energy density of 22.3 W·h·kg–1, and a power density of 5 kW·kg–1. It also has high electrochemical performance even under bending or twisting. The all-solid-state supercapacitors can be easily integrated in series to power different commercial light-emitting diodes without an external bias voltage.

Hierarchical multi-villous nickel–cobalt oxide nanocyclobenzene arrays: morphology control and electrochemical supercapacitive behaviors

Binary metal oxides have been regarded as ideal potential anode materials which display electrochemical performances which surpass those of single metal oxides, in terms of reversible capacity, structural stability and electronic conductivity. In this work, hierarchical multi-villous NiCo2O4 nanocyclobenzene arrays (NCAs) on nickel foam have been fabricated by a simple hydrothermal approach combined with a post-annealing treatment. Such unique nanoarchitectures exhibit a remarkable electrochemical performance, with high capacitance and a desirable cycle lifespan at high rates. When evaluated as an electrode material for supercapacitors, the NCAs supported on nickel foam are able to deliver a high specific capacitance of 1545 F g−1 at a current density of 5 A g−1 in 2 M KOH aqueous solution. In addition, the composite electrode shows excellent mechanical behavior and long-term cyclic stability (93.7% capacitance retention after 5000 cycles). All in all, the fabrication strategy presented herein is simple, cost-effective and scalable, which opens new avenues for the large scale application of these novel materials in energy storage.

Template-free synthesis of ordered ZnO@ZnS core–shell arrays for high performance supercapacitors

In this article, ordered ZnO@ZnS core-shell structures have been produced on a stainless mesh by a two-step approach without using a template. ZnO nanorods fabricated by a chemical vapor method are transferred into a 50 ml autoclave for a second stage ion-exchange reaction followed by heating at 120 °C for 4-16 h. The ZnO core is prepared as the conducting channel and ZnS as the active material. Such unique architecture exhibits remarkable electrochemical performance with high capacitance and desirable cycle life. When evaluating as the electrode for supercapacitors, the ZnO@ZnS core-shell structure delivers a high specific capacitance of 603.8 F g-1 at a current density of 2 A g-1, with 9.4% capacitance loss after cycling 3000 times. The fabrication strategy presented here is simple and cost-effective, which can open new avenues for large-scale applications of the novel materials in energy storage.