A New Redox Mediator (Cupric‐Neocuproine Complex)‐ Modified Pencil Graphite Electrode for the Electrocatalytic Oxidation of H 2 O 2 : A Flow Injection Amperometric Sensor

This paper introduces the cupric‐neocuproine complex ([Cu(Nc) 2 ] 2+ ) as a new redox mediator for the electrocatalytic oxidation of H 2 O 2 . For this purpose, [Cu(Nc) 2 ] 2+ was modified onto a disposable pencil graphite electrode (PGE) surface by using Nafion (Nf) as a cation‐exchange membrane for the effective adsorption of complex. The modified electrode was prepared by immersing Nf‐adsorbed PGE into [Cu(Nc) 2 ] 2+ complex solution (0.40 mM of Cu 2+ and 0.80 mM of Nc prepared at pH 4.76 in 0.10 M acetate buffer). SEM images and EDX spectra of electrodes were presented for the elucidation of their surface morphologies. Cyclic voltammetric results showed that H 2 O 2 was electrocatalytically oxidized at [Cu(Nc) 2 ] 2+ /Nf/PGE, because both the increase in current and the potential shift to a more negative direction were observed for oxidation of H 2 O 2 at [Cu(Nc) 2 ] 2+ /Nf/PGE in comparison to bare PGE. Then, the electrocatalytic activity of [Cu(Nc) 2 ] 2+ /Nf/PGE toward H 2 O 2 oxidation was utilized for amperometric determination of H 2 O 2 in flow injection analysis (FIA) system. Flow injection (FI) amperometric studies showed two linear calibration ranges (1.0‐1000.0 μM ( R 2 =0.9958) and 1000.0‐10000.0 μM ( R 2 =0.9902) with a detection limit of 0.4 μM H 2 O 2 which is considered good for electroanalytical determinations, especially for electrocatalytic oxidation. To test the applicability of the developed FI amperometric hydrogen peroxide sensor, H 2 O 2 contents of some relevant samples were determined.