Scandia-doped zirconia for the electrochemical detection of hazardous dihydroxybenzene (DHB) isomers in water

Abstract

Modified yttria- and scandia-doped zirconium oxides were exploited for the development of an effective electrochemical sensor for the simultaneous detection of dihydroxy benzene (DHB) isomers, i.e. hydroquinone (HQ), catechol (CC) and resorcinol (RS). A morphological, microstructural and electrochemical characterization, by scanning electron microscopy (SEM), infrared spectroscopy (FT-IR), X-ray diffraction (XRD), electrical impedance spectroscopy (EIS), cyclic voltammetry (CV), and square wave voltammetry (SWV), of pure zirconium oxide, zirconium oxide doped with 8% yttria and zirconium oxide doped with 10% scandium (ZrO₂, ZrO₂8Y, and ZrO₂10Sc, respectively), were carried out. Modified electrochemical sensors were fabricated by using a screen-printed carbon electrode (SPCE). Electrochemical analysis conducted in phosphate buffer solution (0.01 M PBS; pH = 7.4) showed the great ability of the ZrO₂10Sc/SPCE sensor to detect simultaneously DHB isomers with high sensitivity. SWV analysis performed with this sensor showed the lowest limits of detection (LODs) among all sensors tested, with values of 0.92, 0.69, and 5.61 nM, for hydroquinone (HQ), catechol (CC), and resorcinol (RS), respectively. In addition, the sensor shows good repeatability and simultaneous detection capability for all DHB isomers. This sensor also showed excellent results for the detection of HQ, CC, and RS in tap and mineral water samples, with good recoveries (90–116%).