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Journal of Solid State Electrochemistry, September 2014, Volume 18, Issue 9, pp 2505-2512.
Gomaa A. M. Ali, Osama A. Fouad, Salah A. Makhlouf, Mashitah M. Yusoff, Kwok Feng Chong.
Faculty of Industrial Sciences & Technology, Universiti Malaysia Pahang, 26300, Gambang, Kuantan, Pahang, Malaysia and
Chemistry Department, Faculty of Science, Al-Azhar University, Assiut, 71524, Egypt &
Central Metallurgical Research and Development Institute, CMRDI, P.O. Box 87, Helwan, 11421, Egypt and
Physics Department, Faculty of Science, Assiut University, Assiut, 71516, Egypt and
Deanship of Scientific Research, Al Imam Mohammad Ibn Saud Islamic University (IMSIU), Riyadh, 11463, Saudi Arabia.
Abstract
In this study, Co3O4/SiO2 nanocomposites have been successfully synthesized by citrate–gel method by utilizing SiO2 matrix for Co3O4 embedment. Spectroscopy analyses confirm the formation of high crystalline Co3O4 nanoparticles; meanwhile, microscopy findings reveal that the Co3O4 nanoparticles are embedded in SiO2 matrix. Electrochemical properties of the Co3O4/SiO2nanocomposites were carried out using cyclic voltammetry (CV), galvanostatic charge–discharge, and electrochemical impedance spectroscopy (EIS) in 5 M KOH electrolyte. The findings show that the charge storage of Co3O4/SiO2 nanocomposites is mainly due to the reversible redox reaction (pseudocapacitance). The highest specific capacitance of 1,143 F g −1 could be achieved at a scan rate of 2.5 mV s−1 in the potential region between 0 and 0.6 V. Furthermore, high-capacitance retention (>92 %) after 900 continuous charge–discharge tests reveals the excellent stability of the nanocomposites. It is worth noting from the EIS measurements that the nanocomposites have low ESR value of 0.33 Ω. The results manifest that Co3O4/SiO2 nanocomposites are the promising electrode material for supercapacitor application.
Significance statement
Dr. K. F. Chong (Assistant Professor) from Universiti Malaysia Pahang and co-workers recently discovered that Co3O4/SiO2 nanocomposites could be the potential material for supercapacitor electrode. Co3O4/SiO2 nanocomposites were prepared by simple citrate-gel method and uniformly dispersed Co3O4 nanoparticles were found embedded in the SiO2 matrix, with mean particle size of 16.5 nm. The prepared Co3O4/SiO2 nanocomposites could achieve specific capacitance of 1143 F g-1, higher than other reported values for cobalt oxides composites. Furthermore, the capacitance retention > 92% after continuous charge/discharge for 900 cycles demonstrated the stability of Co3O4/SiO2 as supercapacitor electrode for long term usage.
