ABSTRACT
Supercapacitors are regarded as a promising energy storage system. Transition metal compounds have been widely used as electrode materials for pseudocapacitors, which possess variable oxidation valence states. Among them, Ni-based materials have drawn a substantial amount of attention. In this work, Ni nanoparticles (NiNPs/NiF) were successfully synthesized on Ni foam by a facile ion implantation method and first studied for the supercapacitor application. At the same time, NiO nanofibers were grown on a Ni foam (NiOF/NiF) for comparison. The NiNPs/NiF electrode delivered a better performance than the NiOF/NiF. The NiNPs/NiF electrode showed a high specific capacitance of 3862 F g-1 at 5 A g-1 and good long-term endurance at a current density of 50 A g-1 after a charge-discharge test of 1000 cycles. The good performance can be attributed to the uniform deposition of the Ni nanoparticles, which provided abundant active sites for the Faradaic reaction. Moreover, the three-dimensional (3D) structure of Ni foam facilitated the electron transfer between the electrode and electrolyte. The excellent performance and facile fabrication make the NiNPs/NiF electrode a promising candidate for high-performance supercapacitors.
ABSTRACT
An ultra-sensitive electrochemical sensor for the detection of insulin was fabricated, using low-cost and environmentally friendly nickel nanoparticles (NiNPs) by ion implantation. The morphology and structure of the NiNPs are characterized by scanning electron microscopy (SEM), revealing diameters ranging from 4 to 8 nm. The insulin assay performances were evaluated by cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS) and chronoamperometry (I-t). The NiNPs-modified indium tin oxide electrode (NiNPs/ITO) showed excellent analytical features, including ultra-high sensitivity (2140 µAµM(-1)) for detecting low concentrations of insulin, an incredibly low detection limit (10 pM) and a wide dynamic range (100 pM to 2400 pM and 1 nM to 125 nM). In addition, the NiNPs/ITO electrode was also used to analyze the insulin concentration in bovine insulin injections. The NiNPs/ITO electrode is expected to be used as a potential biosensor for insulin.
