Facile synthesis of hybrid manganese oxide and multiwalled carbon nanotube by two-step electrodeposition for supercapacitor electrode

Abstract

This work presents a facile synthesis of hybrid manganese oxide and multiwalled carbon nanotube (MnOx/MWCNT) by two-step electrodeposition technique for supercapacitor electrode application. Firstly, MWCNT was deposited onto SS304 substrate by electrophoretic deposition at a constant voltage of 7 V for 5 min. MWCNT solution was prepared using sodium dodecylbenzenesulfonate (SBDS) as a surfactant. Next, MnOx was deposited onto the pre-deposited MWCNT/SS304 substrate by galvanostatic electrodeposition using 0.1 M manganese sulfate (MnSO4) solution as a precursor. The electrodeposition condition was set at a constant current of 1 mA/cm2 for 5-15 min. Nanosheet array of MnOx was formed uniformly on MWCNT. At the deposition time of 10 min, the thickness of MnOx nanosheet was approximately 40 nm. Hybrid MnOx/MWCNT was characterized its electrochemical properties by cyclic voltammetry, galvanostatic charge-discharge, and electrochemical Impedance spectroscopy. Hybrid MnOx/MWCNT shows an improved specific capacitance of 267.03 F·g-1 with a series resistance of 5.17 Ω, surpassing electrode material with only MnOx or MWCNT. The high specific capacitance would be ascribed to the integration of MWCNT and MnOx functions. MWCNT may act as a platform for MnOx deposition, resulting in an increase in electrochemically active surface area of MnOx. The obtained results indicate that this two-step electrodeposition method allows tailor-made hybrid materials with nanoscale control without using harsh and toxic chemicals or high synthesis temperature.