Electrochemical sensors based on functionalized carbon nanotubes modified with platinum nanoparticles for the detection of sulfide ions in aqueous media

Abstract

Vertically aligned carbon nanotube (CNT) arrays were synthesized by thermal chemical vapor deposition (CVD) on stainless steel substrates coated by cobalt nanoparticles as catalyst. Morphological and elemental analyses conducted by scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDX) revealed that bamboo-like CNTs were blocked by Co nanoparticles at the tips. The fabricated nanotubes underwent functionalization by electrochemical oxidation in sulfuric acid, and the subsequent structural studies, as well as Fourier transform infrared (FTIR) spectroscopy confirmed that the tips of functionalized CNTs were opened while oxygenated functional groups were generated at the sidewalls and tube endings. In order to enhance the catalytic performance of the functionalized CNT-based electrodes, platinum nanoparticles were deposited on nanotubes by the potentiostatic and pulse potential electrodeposition processes, and the optimum operating parameters in both techniques were determined. The catalytic activities of these two electrodes towards methanol oxidation were determined by cyclic voltammetry (CV) testing, and a superior electrocatalytic activity and poisoning tolerance were detected for the electrode prepared by pulse deposition. The sensing performance of the pulse plated Pt/CNT electrode for the electrochemical detection and oxidation of dissolved sulfide ions was investigated. A sensitivity of 0.632 μA μM −1 cm −2 and a detection limit of 0.26 μM were obtained, indicating the enhanced capabilities of the developed sensor as a promising candidate for various industrial and environmental applications.

A Novel Electrochemical Sensing Platform for the Sensitive Detection and Degradation Monitoring of Methylene Blue

“…The amino group is introduced for enhancing the electrocatalytic activity of MWCNTs. However, due to the amino group, the modified electrode (NH 2f MWCNTs/GCE), when tested in a blank solution, gives an oxidation peak at 0.03 V. Every material has its own electrochemical oxidation potential [45]. It is interesting to note that the signal does not overlap with the response of MB.…”

Electrical and Electrochemical Sensors Based on Carbon Nanotubes for the Monitoring of Chemicals in Water—A Review

“…The best limit of detection of 0.2 µM is reported with Hematoxylin [ 197 ], a compound reported to foster electrocatalytic oxidation of sulfide. Platinum [ 198 ] nanoparticles (also expected to oxidize sulfide) electrodeposited on vertically aligned CNT arrays perform also very well, comparably to non-functionalized CVD-grown MWCNTs [ 199 ].…”

Synthesis and characterization of a novel non-enzymatic glucose biosensor based on polyaniline/zinc oxide/multi-walled carbon nanotube ternary nanocomposite

“…High-quality and well-aligned MWCNT arrays can be fabricated by thermal chemical vapor deposition (CVD) process which is uniquely superior to the other synthesis methods of carbon nanotubes such as arc discharge and laser-ablation. This method involves the catalytic decomposition of a gaseous carbon precursor at an elevated temperature on the surface of a substrate coated with transition catalysts such as iron, cobalt, or nickel [14]. To gain greater control over the performance of the MWCNT-based electrochemical sensors, low-density vertically aligned MWCNT forests can be synthesized by adjusting the CVD reaction time, temperature, pressure, gas flow rate, nature of the metal catalyst, concentration of the catalyst precursor, and so forth [15].…”