Gao-Feng Chen

Hierarchical NiCo2O4 nanosheet-decorated carbon nanotubes towards highly efficient electrocatalyst for water oxidation

The development of robust and low cost electrocatalysts with highly efficient oxygen evolution reaction capability remains a great challenge for widespread applications in water splitting. Here, spinel NiCo2O4 nanosheets grown on mildly oxidized multi-walled carbon nanotubes (CNTs) have been synthesized via a simple one-pot solution method. Compared with pure NiCo2O4, the as-prepared hierarchical NiCo2O4/CNTs composite exhibits superior OER catalytic properties, i.e. a more negative onset potential, a smaller Tafel slope and higher stability, which may be attributed to the enhanced conductivity of the hybrid, originating from the carbon nanotube substrate. Furthermore, the surface Co/Ni ratio of NiCo2O4/CNTs is changed by the synergistic reactivity between oxygen-enriched groups and metal ions, which improves the catalytic performance of NiCo2O4/CNTs. This electrocatalyst with enhanced OER performance may be a promising candidate for water splitting.

A Porous Perchlorate-Doped Polypyrrole Nanocoating on Nickel Nanotube Arrays for Stable Wide-Potential-Window Supercapacitors.

A bottom-up synthetic strategy is developed to fabricate a highly porous wave-superposed perchlorate-doped polypyrrole nanocoating on nickel nanotube arrays. The delicate nanostructure and the unique surface chemistry synergistically endow the obtained electrode with revealable pseudocapacitance, large operating potential window, and excellent cycling stability, which are highly promising for both asymmetric and symmetric supercapacitors.

Polypyrrole Shell@3D‐Ni Metal Core Structured Electrodes for High‐Performance Supercapacitors

Three-dimensional (3D) nanometal films serving as current collectors have attracted much interest recently owing to their promising application in high-performance supercapacitors. In the process of the electrochemical reaction, the 3D structure can provide a short diffusion path for fast ion transport, and the highly conductive nanometal may serve as a backbone for facile electron transfer. In this work, a novel polypyrrole (PPy) shell@3D-Ni-core composite is developed to enhance the electrochemical performance of conventional PPy. With the introduction of a Ni metal core, the as-prepared material exhibits a high specific capacitance (726 F g(-1) at a charge/discharge rate of 1 A g(-1)), good rate capability (a decay of 33% in Csp with charge/discharge rates increasing from 1 to 20 A g(-1)), and high cycle stability (only a small decrease of 4.2% in Csp after 1000 cycles at a scan rate of 100 mV s(-1)). Furthermore, an aqueous symmetric supercapacitor device is fabricated by using the as-prepared composite as electrodes; the device demonstrates a high energy density (≈21.2 Wh kg(-1)) and superior long-term cycle ability (only 4.4% and 18.6% loss in Csp after 2000 and 5000 cycles, respectively).