Construction and application of NiCo2O4@MnS composite with hierarchical structure for hybrid supercapacitor.

The development of an electrochemical energy storage system with exceptional performance is an important way to address the energy crisis and environmental pollution of the modem world. In this study, an NiCo2O4@MnS composite with a unique hierarchical structure has been successfully synthesized on an NF substrate using the hydrothermal-electrodeposition method. The results indicate that NiCo2O4@MnS possesses superior specific capacitance and excellent cycling stability. At a current density of 2 A g-1, its specific capacitance can reach 2100 F g-1, while the capacitance retention is still 76% after 10 000 cycles at 10 A g-1. Moreover, when the current density is 1 A g-1, the assembled NiCo2O4@MnS//AC device can deliver a specific capacitance of 203 F g-1, and the energy density is up to 55 W h kg-1 at a power density of 697 W kg-1. These outstanding electrochemical properties of NiCo2O4@MnS can be ascribed to the increase in ion diffusion, specific surface area and electronic conductivity due to its unique hierarchical structure and introduction of MnS.

A superior mulberry-like nanoparticle NiB binary catalyst for borohydride oxidation.

A NiB binary catalyst with a unique mulberry-like nanoparticle morphology has been prepared by one-step electrodeposition. The NiB-0.2 catalyst exhibits excellent catalytic activity, selectivity, and stability for the borohydride oxidation reaction. Moreover, a direct borohydride fuel cell using the NiB-0.2 catalyst anode can deliver a peak power density of 453 mW cm-2 and open-circuit voltage of 1.96 V at 343 K. The improved performances are due to the introduction of B. This study may inspire the development of efficient noble-metal-free anode catalysts for DBFCs.

Mg doping of NiMn-LDH with a three-dimensional porous morphology for an efficient supercapacitor.

As a promising supercapacitor electrode material, NiMn-LDH has attracted great attention due to its high theoretical capacity and easy preparation. However, the development and application of NiMn-LDH in supercapacitors are limited because of its poor cycling stability and low electrical conductivity. To solve these problems, a NiMnMg-LDH with a three-dimensional porous morphology has been successfully fabricated by doping with Mg to improve its electrochemical properties. Experimental results indicate that NiMnMg-LDH-7 delivers a specific capacitance of 1772 F g-1 at a current density of 1 A g-1. Moreover, it can still reach 1080 F g-1 when the current density is increased 10 times, suggesting excellent rate capability. The asymmetric supercapacitor (ASC) NiMnMg-LDH-7//AC can provide a high energy density of 28 W h kg-1 at a power density of 700 W kg-1. Furthermore, the energy density can still reach 16 W h kg-1 even if the power density is increased to close to 3500 W kg-1. The capacity retention of this ASC device can reach 74% after 3000 cycles at a current density of 3 A g-1. These excellent properties of NiMnMg-LDH can be attributed to the obvious improvement of its specific surface area and electrical conductivity owing to doping with the element magnesium. We believe that this work could provide a new idea for the preparation of high-performance electrode materials for supercapacitors.