Improved electrogenerated chemiluminescence of luminol by cobalt nanoparticles decorated multi-walled carbon nanotubes

Multi-walled carbon nanotubes (MWCNTs) were decorated with cobalt nanoparticles (Co-NPs) by a simple thermal decomposition method. The prepared nanohybrid material (nanoCo-MWCNTs) was then cast on the surface of a glassy carbon electrode (GCE) as a novel electrocatalyst for the construction of a sensitive electrochemiluminescence (ECL) sensor. The fabricated sensor (GCE/nanoCo-MWCNTs/Nafion) showed excellent electrocatalytic activity toward luminol and H₂O₂ oxidation reactions at neutral media. Under optimal experimental conditions, the ECL signal intensity of the sensor was linear with the concentration of luminol in the range between 80 nM and 140 μM (r = 0.9963) and also with the concentration of H₂O₂ in the range between 1 nM and 240 μM (r = 0.9980). Detection limits (S/N = 3) for luminol and H₂O₂ were 8.7 and 0.2 nM, respectively. The relative standard deviations (RSD) for repetitive measurements of 100 μM luminol (n = 10) and 10 μM H₂O₂ (n = 11) were 1.6% and 2.0%, respectively. Also, the prepared sensor was further modified with glucose oxidase (GOx) to fabricate a glucose ECL based biosensor (GCE/nanoCo-MWCNTs/GOx/Nafion). The fabricated ECL biosensor exhibited excellent performance toward glucose detection in the concentration range between 0.5 and 600 μM with a satisfactory detection limit (50 nM) and reproducibility (2.3%).