Efficient electrocatalytic oxidation of NADH by highly dispersible in situ N-doped ionic liquid-functionalized graphene nanosheets

A suitable ss-nicotinamide adenine dinucleotide (NADH) probe shall be capable of decreasing the oxidation overpotential and improving the electron transfer rate by direct electrocatalytic oxidation of NADH. Taking advantage of the combination of N-doped graphene and ionic liquid (IL) as an electrocatalyst, a facile and useful approach comprising covalent grafting of imidazolium IL on reduced graphene oxide (ie, rGO-IL) and in situ insertion of N-atoms within the graphene framework, using the grafted IL as the N-source (ie, N-rGO-IL), is demonstrated in this study. Additionally, their electrocatalytic efficiency toward NADH oxidation is systematically analyzed. Remarkably low peak potentials at 0.141 and 0.125 V and high current signals are observed for rGO-IL- and N-rGOIL-modified electrodes, respectively, in presence of 200 mu MNADH. Furthermore, the current-time response is recorded at significantly low working potential of 0.0 V and -0.05 V, using rGO-IL- and N-rGO-IL-modified glassy carbon electrode, respectively, on injecting 5 mu M NADH in successive steps. The response shows a good linear relationship from 5 to 30 mu M of successive addition of NADH, with demonstration of correlation coefficients of 0.98 and 0.99, as well as good sensitivity of 50.0 and 39.0 nA mu M-1 cm(-2) (S/N = 3), respectively, for N-rGO-IL and rGO-IL.