Understanding the Photoelectrochemistry of Covalently Grafted Ionic Liquid-Graphene Nanosheets toward NADH Detection

A completely unprecedented photoelectrochemical detection of beta-nicotinamide adenine dinucleotide (NADH), using a covalently grafted imidazolium ionic liquid (IL) on reduced graphene oxide (RGO) nanosheets, has been explored in this study. Importantly, the developed hybrid probe is devoid of any metal or metal oxide nanoparticles, which are generally employed in photoelectrochemical detectors. The covalent grafting of the 1-(3-aminopropyl)-3-methylimidazolium bromide IL, and simultaneous removal of oxygen-containing functionalities from graphene oxide, was achieved in situ in a single step at 145-150 degrees C. The interesting photoelectrochemical behavior of the IL-RGO toward detection of NADH at an applied potential of +0.2 V has been demonstrated as a proof of concept. It was noted that the electron transfer kinetics of NADH oxidation got enhanced due to the presence of photogenerated holes and the grafted imidazolium moiety. One potential application of the proposed material can be the estimation of bioconversion of organic molecules, in which NADH is a cofactor.