Characterization and electrochemical properties of organomodified and corresponding derived carbonized clay

Abstract

Series of alkylammonium modified smectites with different alkylammoinum/clay ratios was synthesized (H series). The obtained organoclays were used as precursors for carbon-clay composite materials (C series). Both set of materials were characterized by X-ray diffraction (XRD), point of zero charge (pH(PZC)), N-2 adsorption-desorption isotherms, Raman spectroscopy and electron paramagnetic resonance (EPR) analysis. XRD analysis of organomodified clays confirmed incorporation of HDTMA(+) into interlamellar space of smectite. Series of carbonized clays showed constant d(001) value of 1.4 nm. The pH(PZC) of two series differed indicating that carbonization changed the profile of pH dependent sites on the clay surface. Textural properties of the H series decreased throughout the series, while in the C series the most developed porous structure was obtained for sample where HDTMA(+) loading was equal to cation exchange capacity. Raman spectroscopy showed that amorphous carbon was formed during carbonization process. The obtained materials were used as modifiers of carbon paste electrode and investigated using electrochemical impedance spectroscopy, cyclic voltammetry and square wave voltammetry. The comparison of electrochemical behavior of H series and C series showed the importance of interlamellar species for charge transfer process. The investigation of influence of composition of carbon paste and form of added carbon showed that performance of carbon-clay based electrodes depended on synergy of different factors.