A novel manganese(II) sulfide-decorated reduced graphene oxide flexible and free-standing paper for electrochemical detection of ascorbic acid

With the growing demand for wearable and portable electronic detectors in the modern world, the development of flexible and free-standing electrode materials has become increasingly important. In recent years, flexible, free-standing, cut-to-size, and lightweight composite graphene-based papers have garnered significant attention in the development of wearable and portable electrochemical sensors. In this study, a novel, flexible, and freestanding graphene-based paper electrode decorated with manganese(II) sulfide (MnS) was designed for the amperometric determination of ascorbic acid (AA). MnS synthesized via a hydrothermal method was added to a graphene oxide (GO) dispersion to form a MnS/GO composite, which was then processed by mold-casting and chemical reduction to produce MnS/reduced graphene oxide paper (MnS/rGOP). The characterization of the prepared flexible MnS/rGOP was successfully carried out using field-emission scanning electron microscopy, transmission electron microscopy, X-ray photoelectron spectroscopy, energy-dispersive X-ray spectroscopy, X-ray diffraction, and Raman spectroscopy. The characterized MnS/rGOP exhibits a wide linear range (0.3-5100 mu M) and a low detection limit (90 +/- 0.98 nM) for AA detection, operating at a relatively low potential of + 0.18 V. Moreover, the MnS/rGOP electrode retained 93.8% of its current response after bending, preserved 83.5% of its peak current after 30 days, and exhibited excellent reproducibility with only a 1.5% variation in peak current density. The recovery rates of AA in real samples ranged from 94.8% to 104.1%. This research presents, for the first time, the fabrication and application of graphene-based paper loaded with MnS to develop a novel, flexible, free-standing, and highly sensitive electrochemical detection for AA.