Fabrication and Characterization of Electrochemical Organophosphate Sensor Device Based on Doped Tin Oxide Nanoparticles

Herein, we report the effect of Co and Cu as dopant on the electrochemical characteristics of the SnO2 nanomaterial by synthesis using a sol-gel method. The synthesized materials were characterized for structural, morphological and elemental determination using suitable techniques which are illustrated in results indicating formation of composite nanomaterial of SnO2 . These synthesized materials were then used as working electrode in the form of a screen printed electrode to determine the organophosphate (OP) sensing characteristics. Conventional electrochemical techniques such as cyclic voltammetry (CV), scan rate studies and impedance spectroscopic studies were conducted for several OP concentration from 0.01 ppm to 50 ppm prepared in phosphate buffer solution. An attempt was made by developing an algorithm to ascertain the equivalent circuit and computing the component values against the values provided by the equipment interface/analysis software. In case of CV studies, a well-defined and distinct oxidation and reduction peaks are observed at different potential values indicating the changes due to the dopants. The estimated sensitivity values for pristine SnO2 is 0.4 mu A/ppm (3.2 mu A/ppm cm(2)), for CoSnO2 is 2.9 mu A/ppm (23.1 mu A/ppm cm(2)) and for CuSnO2 is 0.1 mu A/ppm (0.8 mu A/ppm cm(2)) when estimated over the wider range from 0.01 ppm to 50 ppm. The sensitivity values will be much higher in the range of 0.01 to 10 ppm. As a case study, Cu-doped SnO2 was analyzed for equivalent circuit analysis which shows a mixed kinetic reaction, as against the simple Randel's cell circuit.