Polypyrrole and graphene quantum dots @ Prussian Blue hybrid film on graphite felt electrodes: Application for amperometric determination of l-cysteine

A novel polypyrrole (PPy) and graphene quantum dots (GQDs) @ Prussian Blue (PB) nanocomposite has been grafted on a graphite felt (GF) substrate (PPy/GQDs@PB/GF), and has been proven to be an efficient electrochemical sensor for the determination of l-cysteine (l-cys). GQDs, which were fabricated by carbonization of citric acid and adsorbed on GF surface ultrasonically, played an important role for promoting the synthesis process of PB via a spontaneous redox reaction between Fe3+ and [Fe(CN)6]3−. The PPy film has been electro-polymerized to improve the electrochemical stability of the PPy/GQDs@PB/GF electrode. The as-prepared electrode was characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), infrared spectroscopy (IR), X-ray diffraction (XRD) and electrochemical methods. It exhibited an excellent activity for the electrocatalytic oxidation of l-cys, with a detection sensitivity equal to 0.41Amol−1 L for a concentration range of 0.2–50μmolL−1, and equal to 0.15Amol−1 L for a concentration range of 50–1000μmolL−1. A low detection limit of 0.15μmolL−1, as well as a remarkable long-time stability and a negligible sensitivity to interfering analytes, were also ascertained. •PB was promoted by GQDs through a mild method on GF substrate for the first time.•The electrochemical stability of the sensor was improved by Polypyrrole film.•Low detection limit and high detection sensitivity for L-cys detection.