Probing the electrochemical behaviour of SWCNT–cobalt nanoparticles and their electrocatalytic activities towards the detection of nitrite at acidic and physiological pH conditions

Abstract

a b s t r a c tThe electrochemical decoration of edge plane pyrolytic graphite electrode (EPPGE) with cobalt and cobalt oxide nanoparticles integrated with and without single-walled carbon nanotubes (SWCNTs) is described. Successful modification of the electrodes was confirmed by field emission scanning electron microscopy (FESEM), AFM and EDX techniques. The electron transfer behaviour of the modified electrodes was investigated in [Fe(CN)6] 3−/4− redox probe using cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) and discussed. The study showed that cobalt nanoparticles modified electrodes exhibit faster electron transfer behaviour than their oxides. The catalytic rate constant (K) obtained at the EPPGE-SWCNT-Co for nitrite at pH 7.4 and 3.0 are approximately the same (∼3 × 10 4 cm 3 mol −1 s −1 ) while the limits of detection (LoD = 3.3ı/m) are in the M order. From the adsorption stripping voltammetry, the electrochemical adsorption equilibrium constantˇwas estimated as (13.0 ± 0.1) × 10 3 M −1 at pH 7.4 and (56.7 ± 0.1) × 10 3 M −1 at pH 3.0 while the free energy change ( G • ) due to the adsorption was estimated as −6.36 and −10.00 kJ mol −1 for nitrite at pH 7.4 and 3.0, respectively.

Substrate-induced assembly of PtAu alloy nanostructures at choline functionalized monolayer interface for nitrite sensing

“…According to the slope of E pa versus log v plot, n a was calculated to be 1.08, suggesting that the rate-determining step in overall oxidation process of nitrite was associated with a single electron transfer procedure, which was in agreement with previous report [33]. It was proved that the final product of nitrite oxidation was NO 3 À [34,35], therefore, the electrochemical oxidation of nitrite underwent two successive reactions, involving the formation of NO 2 as the first step, followed by a disproportionation reaction of NO 2 (Eqs. (3) and (4)).…”

Bond breaking electron transfer across a conducting nanowire(nanotube)/electrolyte solution interface: The role of electrical double layer effects

“…Although a number of various electrochemical systems of nanosize were probed recently using different experimental technique (see, e.g., Refs. [28][29][30][31][32][33][34][35][36][37][38][39][40][41]), the authors investigated the averaged properties of arrays of carbon nanotubes and metal nanowires. Reliable kinetic measurements on a single nanosize electrode remain still an exceedingly complicated and challenging problem.…”

Novel 1,4‐Substituted‐1,2,3‐Triazoles as Antitubercular Agents

“…Such high tafel slope implies a strong binding of reactants or intermediates on the electrode surface or reactions occurring within a porous electrode structure 34–37. Based on previous reports, the α value smaller than 0.5 in electro‐reduction systems, and higher than 0.5 in electro‐oxidation systems, indicate a more favored reaction mechanism 35, 36. Thus, a α value of 0.2 obtained here may explain why the electrochemical reduction of H 2 O 2 is highly favored on the PdAgNPs/GC electrode.…”