This work reports the fabrication of a robust and high-performance CNT/Ag electrode via catalytic chemical vapor deposition of ethylene at 800 °C. The structure and quality of the prepared CNT electrode were investigated for the properties required for high electrochemical performance. SEM and TEM showed aligned-multiwalled carbon nanotubes. Raman spectrometry and XRD proved the formation of well-graphitized CNT with high crystallinity. XPS results indicated that sp2 C-C represents the highest percentage of the composition of the produced CNT with the presence of few carbonyl and carboxylate groups. The fabricated CNT/Ag electrode showed a strong adhesion of CNT to the Ag substrate. CNT/Ag Electrode was successfully applied as a differential electrolytic potentiometric sensor to determine ascorbic acid through the sequential injection analysis method. Both direct current and square wave were applied for electrode polarization. Parameters such as dc current and square-wave period were optimized. A current of 42 µA/cm2 was found to be the optimum while a 20% biased square wave provided the best results. The optimum flow rate of the KIO3 reagent was in the range of 75 – 90 µL/sec. The CNT/Ag electrode showed a fast equilibrium, good sensitivity, and reproducibility, as well as durability for long-term use. Ascorbic acid was determined in the concentration range of 0.06 – 0.85 mmol/L with a good linear relationship obtained for both types of polarization.

CVD fabrication of CNTs based potentiometric sensor for determination of ascorbic acid

ACS Spring 2022

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.