Surface modification of titania nanotube arrays with crystalline manganese-oxide nanostructures and fabrication of hybrid electrochemical electrode for high-performance supercapacitors

Abstract

A hybrid electrochemical microelectrode is fabricated with a simple and cost-effective sono-chemical method, which consists of anodized titania nanotube arrays covered with manganese oxide nanostructures (nanorods+nanoparticles mixed morphology). The modification of the surface of the highly porous titania nanotube arrays with high-surface-area manganese oxide nanomaterials leads to considerable increment in the surface roughness of the composite electrode, which manifests high active surface sites of the electrode, and hence, leads to excellent electrochemical properties of the hybrid samples. The cyclic voltammetry and galvanostatic charge–discharge characterizations depict considerably improved electrochemical performance with high areal capacitance values. The areal capacitance of the composite electrode is obtained around 65mFcm−1 @ 1.0mVs−1 scan rate, which is more than 160 times higher than the control electrode (TNT, 0.4mFcm−1 @ 1.0mVs−1 scan rate). The composite electrode also depicts high capacity retention with only 4% decrement in the capacitance value over 2500 cycles. Also the composite electrode reveals almost 65 times increment in the power density for a mere 2 times decrement in the energy density. This high cyclic stability along with excellent energy-power performance indicates very good applicability in practical charge storage devices. The electrochemical impedance spectroscopic studies showed near-ideal capacitive performance with very low charge transfer resistance. This superior supercapacitive performance of the hybrid electrode is due to the combinatorial effect of electric double-layer capacitance of TNT and pseudocapacitance of MO as well as high active surface sites of the electrode for higher utilization of the active material. Therefore, this simple and low-cost technique to fabricate hybrid microelectrode with superior electrochemical properties can be very useful for high-performance supercapacitors.