posted on 2022-12-14, 16:06authored byRania
A. Nuamah, Saleema Noormohammed, Dilip K. Sarkar
Nanostructured Co–Co3O4 composite
thin films deposited on nickel foam (NF) using combined cyclic voltammetry
(CV) and pulse reverse potential (CV PRP) modes of electrodeposition
from an electrolyte composed of CoCl2 and Co(CH3COO)2 precursor salt solutions with varied molar ratios
demonstrated a dependency of the supercapacitance performance over
the precursor components’ molar ratios. The specific capacity
and its retention were found to increase with increasing CoCl2 in the electrolyte with a starting value of 474.6 C/g (791
F/g) at an applied current load of 1 A/g for a molar ratio of Co(CH3COO)2:CoCl2 of 100:0. High specific
capacity of 1548 C/g (2580 F/g) and large retention (90.5%) were obtained
at a critical molar ratio of Co(CH3COO)2:CoCl2 of 20:80. However, with 100% CoCl2 in the electrolyte,
the specific capacity lowered to 276 C/g (460 F/g) with poor retention
of only 60%. Crystallinity and morphological features, driven by the
electrolyte concentration with molar variations of the deposited films,
have been found to influence the specific capacitance performance.
The degree of crystallinity, and the presence of Co and Co3O4 phases for the different molar ratios have been revealed
by X-ray diffraction (XRD) studies. The diverse morphological features
obtained by scanning electron microscopy (SEM) and the varying quantities
of Co and O in the Co–Co3O4 nanocomposite
thin films as confirmed by energy-dispersive X-ray spectroscopy (EDX)
spectra correlate well with the electrochemical performance. The phase
composition was further confirmed by the presence of Co–O bonds
via the attenuated total reflection–Fourier transform infrared
(ATR-FTIR) spectra obtained on these films.