Electrochemical synthesis of Fe/Al-layered double hydroxide on a glassy carbon electrode: application for electrocatalytic reduction of isoniazid

Abstract

IntroductionAnionic clays or layered double hydroxide (LDH) materials are positively charged nano-structures. The chemical and physical properties of LDHs are very close to hydrotalcite, [Mg 6 Al 2 (OH) 16 ]CO 3 .4H 2 O, due to their structural similarities [1]. The structure of layered double hydroxides (LDHs) is based upon the structure of brucite, and the partial substitution of the divalent cations for the trivalent ones in their network that makes brucite positively charged. The positive charges appeared in the layers are neutralized by the anions existing between the layers. The general chemical formula for LDHs can be expressed as [M II 1−x M III x (OH) 2 ] x+ [A n− x/n · mH 2 O] x− , where M II represents a divalent metal such as Mg, Co, Ni, Cu, Zn, and Ca, M III is a trivalent metal such as Al, Cr, Fe, and Ga, and A n− is an anion. x is equal to the M III /(M II + M III )ratio. The value for x has been reported to be in the range of 0.2-0.33 in the formation of a pure LDH phase. The anions and water molecules intercalated into the LDH interlayers can be replaced with other organic and inorganic anions [2][3][4]. Due to their suitable properties such as large specific surface area, good chemical and thermal stability, high anion exchange capacity, adsorption property, and catalytic activity, LDHs have many applications in different fields such as catalysis [5,6], photochemistry [7, 8], polymer additives [9], supercapacitors [10], anti-corrosion coatings [11], pharmaceuticals [12, 13], separation technology [14-16], electrode surface modification, and sensors [17, 18]. Different methods have been introduced for the synthesis of LDHs such as the thermal or hydrothermal co-precipitation [19, 20], area hydrolysis [21], and the ion exchange method [22]. In addition to the aforementioned methods, novel methods including the sol-gel [23] and electrochemical [24, 25] ones have been reported for the synthesis of Abstract Fe/Al-layered double hydroxide (Fe/Al-LDH)was synthesized on a glassy carbon electrode (GCE) by a novel and simple electrochemical method. The electrochemical characterization of Fe/Al-LDH deposited on GCE was investigated in a 0.1 M NaOH solution. Moreover, the LDH film obtained was characterized by X-ray diffraction (XRD), Fourier transform infrared (FT-IR) spectroscopy, scanning electron microscopy (SEM), and energy dispersive X-ray (EDX). The obtained results showed that Fe/ Al-LDH was generated on GCE by the electrochemical method, and that the obtained film was highly pure. The electrochemical behavior of isonicotinic acid hydrazide or isoniazid (INZ) at LDH/GCE was studied by the electrochemical techniques including cyclic voltammetry, differential pulse voltammetry, and amperometry. The obtained results indicated an excellent electrocatalytic reduction activity for the Fe/Al-LDH-modified GCE of INZ. Under the optimized conditions for determination of INZ the calibration curves are linear in the ranges of 4.9-650.0 and 4.9-770.0 μM with limit of detections of 4.0 and 7.0 μM for differential...

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