Electrocatalytic sensing of hydrogen peroxide using a screen printed carbon electrode modified with nitrogen-doped graphene nanoribbons

We have synthesized nitrogen-doped graphene nanoribbons (N-GrNRs) by unzipping multi-walled carbon nanotubes (CNTs) under strongly oxidizing conditions and subsequent doping with nitrogen by a low-temperature hydrothermal method. The N-GNRs were characterized by transmission electron microscopy, X-ray diffraction, X-ray photoelectron spectroscopy and Raman spectroscopy, and assembled on a disposable screen-printed carbon electrode to give a sensor for H2O2 that was characterized by cyclic voltammetry, electrochemical impedance spectroscopy, chronocoulometry and chronoamperometry. The nano-modified electrode displays enhanced electron transfer ability, and has a large active surface and a large number of catalytically active sites that originate from the presence of nitrogen atoms. This results in a catalytic activity towards H2O2 reduction at near-neutral pH values that is distinctly improved compared to electrodes modified with CNTs or unzipped (non-doped) CNTs only. At a working potential of -0.4 V (vs. Ag/AgCl), the amperometric responses to H2O2 cover the 5 to 2785 mu M concentration range, with a limit of detection as low as 1.72 mu M. This enzyme-free electrochemical sensor exhibits outstanding selectivity and long-term stability for H2O2 detection.