In recent years, a number of methods in favour of photoelectrocatalytic oxidation of reduced β-Nicotinamide Adenine Dinucleotide (NADH) based on polyphenothiazine formaldehyde (PPF) [1], poly-Neutral Red (poly-NR) [2], electropolymerized methylene blue [3] and thin film of poly-Hematoxylin (poly-HT) [4] modified electrode have been used. Here, the immobilization of electrogenerated chloropromazine (CPZ) oxidation products onto the graphene nanosheets-CdS Quantum dot (GNs-QD)/Ionic Liquid (IL) nanocomposite modified glassy carbon (GC) electrode for photoelectrocatalytic determination of NADH and fabrication of alcohol biosensor is described. A facile, one-step, solvothermal approach for the synthesis of GNs-QD nanocomposite in dimethyl sulfoxide (DMSO) has been established, in which reduction of Graphene Oxide (GO) to GNs and CdS QDs production occurred at the same time [5]. Potential cycling was used for oxidation of CPZ and producing an electroactive redox couple, which strongly adsorbed on the electrode surface modified with GNs-QDs/IL nanocomposite. This couple can act as excellent mediator for electrocatalytic oxidation of NADH. The cyclic voltammetric results indicated the ability of CPZ oxidation products/GNs-QD/IL modified GC electrode to electrocatalytic and photoelectrocatlytic oxidation of NADH at a very low potential (- 50 mV vs. Ag/AgCl) and subsequently, a considerable decrease in the overpotential by about 700 mV compared with the bare GC electrode. After irradiation, the electrode yields a strongly increased electrocatalytic current compared to the current without irradiation. Also, in the presence of irradiation, oxidation potential of NADH move towards more negative potential compared to the potential without irradiation.
