Carbon Nanotubes as Nanosensor for Differential Electrolytic Micropotentiometry

Abstract

Carbon nanotubes as nanosensor were synthesized on the surface of the silver electrode using floating catalyst chemical vapor deposition reactor. Acetylene gas was used as a carbon source, ferrocene as a source of the iron nanocatalyst and hydrogen as a carrier and an activate agent. Several runs were performed to find the optimum conditions that produce sensitive Ag-CNTs electrodes. The electrodes obtained at each run were characterized by SEM. The optimum conditions that produce sensitive Ag-CNTs were found to be at a reaction time of 15 minutes, reaction temperature of 700˚C, hydrogen flow rate of 25 ml/min and an acetylene flow rate of 75 ml/min. These optimum conditions were confirmed from the normal behavior of the resulting Ag-CNTs electrodes in the titration of 10 µL of chloride using dc differential electrolytic potentiometry. When conditions that differ from the optimum ones were applied in the preparation of the AgCNTs electrodes, abnormal titration curves were obtained. The superiority of the Ag-CNTs electrodes was demonstrated by the successful applications of these electrodes as an indicating system in the micro titrations of different volumes of cyanide solution with silver nitrate reach. By applying this technique a volume of 1.2 µL sample of cyanide was successfully titrated. The normal behavior of the Ag-CNts electrodes was compared to that of the normal silver electrodes which exhibit an abnormal behavior.