A New Composite Based on Electroactive Zirconium Phosphate: Morfology, Structure and Their Behavior as a Voltammetric Sensor in the Ascorbic Acid Detection

Abstract

An electroactive and chemically stable composite was obtained from zirconium (IV) isopropoxide (ZrI) and phosphoric acid (ZrP). The ZrP was characterized by techniques such as Fourier transform infrared spectroscopy, C-13 and P-31 nuclear magnetic resonance, X-ray diffraction, scanning electron microscopy, energy dispersive X-ray spectroscopy, thermogravimetric analysis, X-ray photoelectron spectroscopy, surface area and porosity and cyclic voltammetry. Voltammetric behaviour of the ZrP was obtained using of a modified graphite paste electrode in a potential range from -0.20 to 1.00V (vs Ag/AgCl). ZrP showed one redox couple with average potential E = 0.30V (vs Ag/AgCl(sat.)) (40% w/w; v=20mV s(-1); KCl; 1.00mol L-1). It was tested on electrocatalytic detection of ascorbic acid using cyclic voltammetry and square wave voltammetry. The modified electrode showed a detection limit of 2.4x10(-5) mol L-1, with relative standard deviation of +/- 3% (n=3) and amperometric sensitivity of 11.7mA/mol L-1 (R=0.999) by using the cyclic voltammetry technique and a detection limit of 1.10x10(-4) mol L-1 with relative standard deviation of +/- 2% (n=3) and amperometric sensitivity of 126.9mA/mol L-1 (R=0.998) by using the square wave voltammetry technique.