WITHDRAWN: Electrochemical detection of heavy metals using carbon quantum dots modified with metal oxides

Abstract

Abstract The high toxicity of chemical pollutants and its detrimental effects to the living organisms has led to significant public concern. Hence it is very much necessary to monitor the level of these toxic ions in the environment using an appropriate sensor. In order to detect the heavy metal such as lead, mercury, cadmium etc. in water, there exist a need to develop a novel sensing technology for more sensitivity and rapid detection. The use of classical methods for the detection of the toxic ions in water is both tedious and time consuming. Nanomaterial of carbon serve as a powerful tool in analyzing these heavy metal ions due to their selectivity and sensitivity to one cation, owing to their excellent photoluminescence and photophysical properties.In this present work ,green synthesis of carbon quantum dots was carried out using lemon juice and onion juice. These CQD’s were then doped with metal oxides such as bismuth oxide and zinc oxide. These metal oxide doped CQD’s improves the sensitivity and electrical conductivity of electrodes and hence increases the rate of electrochemical reaction. The carbon dots and metal oxide doped carbon dots were characterized using IR technique, UV –Visble spectroscopy and SEM. The sensing property of electrode towards heavy metal was investigated by modifying the electrode with CQD’s, CQD’s doped with metal oxide and anionic polymer (nafion).The cyclic voltammetric studies were carried out with glassy carbon electrode modified with CQD/Bi203/Nafion. The cyclic voltammograms obtained showed that glassy carbon electrode modified with CQD/Bi203/Nafion showed excellent sensing property towards lead.