The Capacitive Behavior of Polyluminol on Carbon Nanotubes Electrodes

Abstract

A polymerized luminol carbon nanotube (CNT) composite electrode was developed via an in situ chemical polymerization (CpLum) process. Density functional theory (DFT) simulation suggested the luminol molecules were preferentially aligned flat on the CNTs. This was further demonstrated through a morphological study, which showed the CpLum wrapped around each CNT homogeneously with an average thickness of 4.5±1.5 nm. The surface chemical analysis by X-ray photoelectron spectroscopy (XPS) revealed a progressive increase in the nitrogen content and stabilized at 9 %. Deconvolution of the high-resolution N 1s spectra suggested the presence of secondary and tertiary amine functional groups, which are the signatures of polymerized luminol. The composite electrodes exhibited a pseudocapacitive-like behavior with 3.5 times increase in charge storage. The contributions from the CpLum coating and CNT substrate were differentiated and were further deconvoluted to quantify the capacitive charge storage of each component. The thin CpLum coating contributed 70 % of the total charge storage through pseudocapacitance. CpLum-CNT electrodes also showed a high rate capability and good cycling stability, very promising for electrochemical capacitors.