FeOOH-polypyrrole-multiwalled carbon nanotube ternary nanocomposite fabricated by liquid-liquid co-extraction technique for supercapacitors application

FeOOH-polypyrrole-multiwalled carbon nanotube (FeOOH-PPy-MWCNT) ternary nanocomposite for supercapacitor negative electrodes are prepared by liquid-liquid co-extraction (LLCE) technique using decylphosphonic acid (DPPA) as efficient co-extractor. LLCE offers advantages of reduced agglomeration and facilitates mixing of the individual components. This technique allows direct particle transfer from the reaction medium to the electrode fabrication slurry. The mechanism of LLCE extraction is analyzed. The synergetic effect of FeOOH, PPy and MWCNT significantly enhances charge storage properties of the FeOOH-PPy-MWCNT ternary nanocomposite electrodes. The FeOOH-PPy-MWCNT ternary nanocomposite electrode shows an integral capacitance of 5.1 F cm−2 (137.9 F g−1) in a negative potential window, which is significantly higher than capacitances of binary FeOOH-MWCNT and PPy-MWCNT nanocomposites. Moreover, the ternary composite offers advantages of a larger voltage window. Testing results for the ternary composites at different electrode potentials show reduced AC impedance. The asymmetric supercapacitor device composed of FeOOH-PPy-MWCNT anode and MnO2-MWCNT cathode exhibits a high areal capacitance of 2.5 F cm−2 at scanning rate of 2 mV s−1 in a voltage window of 1.6 V at an extremely small impedance. This facile LLCE fabrication technique opens a door for fabrication of advanced nanocomposite materials for supercapacitor applications.