Novel synthesis of multi-layered rGO/Fe3O4 nanocomposite in a single step and its efficient electrochemical sensing of vitamin C

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A facile single-step solvothermal growth of rGO/Fe3O4 nanocomposite was achieved at a temperature of 230 °C by using CaC2 as a carbon source for rGO and an iron source. The synthesised rGO/Fe3O4 nanocomposite was characterised by XRD, Raman, FTIR, TEM, XPS and EDX analyses. The XRD data revealed that the as-grown Fe3O4 nanoparticles were highly crystalline, and the average particle size obtained from the TEM analysis was 13 nm. The surface dispersion of agglomerated, almost spherical-shaped Fe3O4 nanoparticles stacked on the surface of rGO sheets was confirmed from TEM analysis. The calculated intensity ratio of the G and D bands from the Raman spectra points to the presence of multi-layered rGO in the nanocomposite. From the XPS spectra, the binding energies corresponding to C 1 s, O 1 s and Fe 2p were obtained, and the electronic relationship between Fe3O4 and rGO in the sample was evidenced by Fe-O-C bonding. The rGO/Fe3O4 nanocomposite was tested for the electrochemical detection of L-AA using three electrode setup. From the EIS spectra, the rGO/Fe3O4/GCE exhibit high conductivity and faster electron transfer rates and thus was expected to give enhanced electrochemical properties. Excellent electrochemical properties were observed towards L-AA detection, and LOD was obtained to be 18.5 μM. The rGO/Fe3O4/GCE also achieved high sensitivity of the order of 92 μA mM−1 cm−2 towards the L-AA sensing. Moreover, we addressed the poor selectivity, short linear detection range and poor repeatability of the previously reported L-AA sensors and covered all these defects. The rGO/Fe3O4/GCE shows excellent repeatability, selectivity and a higher detection range (10 μM to 100 mM) for the electrochemical evaluation of L-AA. Also, the experiments were extended to the real sample analysis in the commercial vitamin C tablets, and the results show that rGO/Fe3O4/GCE is suitable for large scale applications.