ABSTRACT
Conductive polymers have become a remarkable candidate for electrode materials of supercapacitors. Polyaniline (PANI) is the most promising contender for supercapacitors because of its easy method of synthesis, low cost, and higher choice in the improvement of energy storage applications. The main issue in the use of PANI in supercapacitors is its lower stability. In this work, PANI@Fe-Ni codoped Co3O4 (PANI@FNCO) nanocomposite has been prepared by in situ addition of 10 wt % FNCO as fillers in the PANI matrix. The nanocomposites were then characterized via scanning electron microscopy (SEM), X-ray diffraction (XRD), Fourier transform infrared spectroscopy, thermogravimetric analysis, and differential scanning calorimetry to observe the morphology, crystal structure, functional groups, and thermal stability of samples, respectively. SEM results showed that FNCO was fairly dispersed in the PANI matrix, while XRD results showed a broad peak for nanocomposites because of the semicrystalline nature of polymers. The electrochemical properties of the samples were analyzed via cyclic voltammetry, galvanostatic charge and discharge, and electrochemical impedance spectroscopy. PANI@FNCO nanowires are found to overcome the shortcomings in electrochemical energy storage devices by exhibiting a higher value of specific capacitance of 1171 F g-1 and energy density of 144 W h kg-1 at a current density of 1 A g-1. Moreover, the FNCO nanowires also showed a cyclic charge/discharge stability of 84% for 2000 cycles.
ABSTRACT
Magnesium has attracted a lot of attention as a new class of biodegradable material. The surface properties of magnesium in simulated body fluid (SBF) were investigated in the current research work. Cast magnesium samples with different surface characteristics were prepared which were then placed in SBF for 2, 4 and 8 days. This led to the formation of hydroxylapatite coating on their surfaces. The solution was changed at regular intervals to maintain a pH of 7.6. Other Mg samples were anodized at 40 V and 60 V to create a uniform layer of oxide on them and then their activity in SBF was compared with the casted samples of Mg. It was found that corrosion rate varies as the immersion time increases. Magnesium undergoes localized corrosion with pits and cracks forming on the surface of the samples. This was due to the aggressive corrosive nature of SBF.