Fast and clean dielectric barrier discharge plasma functionalization of carbon nanotubes decorated by electrodeposited nickel oxide: Application to glucose biosensors

Multi-walled carbon nanotubes (MWCNTs) were functionalized using a dielectric barrier discharge plasma in presence of H2O-saturated air at 70˚C and atmospheric pressure. The functionalized MWCNTs (F-CNTs) were decorated with electrochemically deposited 10 nm NiO nanoparticles, followed by immobilization of glucose oxidase (GOx) and the modified electrode was utilized for electrochemical detection of glucose. TEM, FE-SEM, TPD and XPS techniques were used to characterize the NiO/F-CNTs samples. The maximum amount of oxygenated functional groups such as carbonyl, hydroxyl and carboxylic groups was formed at the plasma exposure time of 4 min. The optimum chronoamperometric deposition time of NiO was 3 min. The presence of GOx on the NiO/F-CNTs electrode displayed a quasi-reversible and surface-controlled redox wave around −0.52 V with a peak to peak separation of 0.05 V. The GOx/NiO/F-CNTs electrode showed a linear performance in the range of 0.2-3.8 mM glucose with detection limit of 93.0 µM and sensitivity of 2.16 µA.mM−1.