Three dimensional flower like cobalt sulfide (CoS)/functionalized MWCNT composite catalyst for efficient oxygen evolution reactions

In this work, a nanocomposite of CoS reinforced with functionalized multiwalled carbon nanotubes (MWCNTs) has been prepared using ultrasonication and complexation. Further, CoS/CNT composite was studied by X-ray diffraction studies, Field-emission scanning electron microscopy and X-ray photoelectron spectroscopy to study the crystallinity, surface morphology, chemical composition and chemical states respectively. Electrochemical studies show the appearance of reversible redox peaks, indicating a pseudocapacitive nature of CoS/CNT nanocomposite electrodes. The electrochemical measurements show that CoS/CNT nanocomposite electrode is catalytically more active for oxygen evolution reaction (OER) with an overpotential of 347 mV and a current density of 15 mA/cm(2) (Tafel slope of 142 mV/decade) in alkaline solution. The low charge transfer resistance and high double layer capacitance of CoS/CNT studied using electrochemical impedance spectroscopy. The stability and amperometry studies also confirmed that CoS/CNT nanocomposite is able to maintain excellent performance even after 500 cycles without any degradation.