Abstract
In the present research, we have reported the applicability of multiwall carbon nanotube–doped polypyrrole-carbon black (MWCNTs/PPy-C) as a potential nitrite sensor. Sophisticated characterization tools including X-ray diffraction, X-ray photoelectron spectroscopy, Raman spectroscopy, infrared spectroscopy, and transmission electron microscopy were systematically employed to characterize the as-fabricated electrocatalyst. The electro-catalytic and sensing performance were evaluated using cyclic voltammetry (CV), linear sweep voltammetry (LSV), electrochemical impedance spectroscopy (EIS), and amperometric (
i-t
) techniques. The as-fabricated sensor electrode shows remarkable electrocatalytic activity towards nitrite ion electro-oxidation. The nitrite oxidation using the proposed catalyst follows a diffusion-controlled process with kinetic parameters having electron transfer coefficient (
α
) as 0.50 and the standard rate constant (
k
0
) as 5.488
×
10
−3
cm s
−1
. The MWCNTs/PPy-C modified sensor electrode exhibited excellent sensitivity of 0.1558 µAµM
−1
cm
−2
over the dynamic concentration range (0.50–10.50 mM) (for linear sweep voltammetry: LSV) and 0.1171 µAµM
−1
cm
−2
over the concentration range (5–9500 µM) (for amperometry:
i-t
characteristics). The detection limit was calculated to be 2.30 µM and 3.06 µM (S/N = 3) for LSV and
i-t
technique, respectively. Furthermore, the proposed sensor electrode exhibited good selectivity towards nitrite ion detection in the existence of common interfering metal ions and biomolecules as well as demonstrated excellent operational stability, reproducibility, and repeatability. Therefore, such developed electrocatalyst demonstrates a promising sensor material for the competent detection of nitrite ions by the electrochemical method.
Graphical abstract