Electrocatalytic oxidation and determination of ascorbic acid in the presence of dopamine at multiwalled carbon nanotube–silica network–gold nanoparticles based nanohybrid modified electrode

Multiwalled carbon nanotubes (MWNTs) was grafted onto silica network (MWNT–silica-NW) by sol–gel process. MWNT–silica-NW was further electrodeposited with gold nanoparticles (AuNPs). The morphology of the GC/MWNT–silica-NW–AuNPs modified electrode (ME) was analyzed by field emission scanning electron microscopy (FE-SEM). Cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) were used to evaluate the electrochemical performances of GC/MWNT–silica-NW–AuNPs-ME. Ascorbic acid (AA) was found to be electrocatalytically oxidized at GC/MWNT–silica-NW–AuNPs-ME due to the synergistic influence of MWNTs, silica-NW and AuNPs. The MWNT–silica-NW–AuNPs-ME sensor electrode presents a high sensitivity (8.59 μA/mM) and selectivity for AA in the presence of dopamine (DA). Differential pulse voltammetry revealed that the sensor electrode exhibited excellent selectivity for AA in the presence of large excess of DA with a large potential separation of ∼0.26 V. The effective electrocatalytic activity, excellent peak resolution and ability for independent determination of DA in the presence of AA reveal that MWNT–silica-NW–AuNPs-ME is suitable for simultaneous and selective determination of DA and AA.