Facile one-pot solvothermal synthesis of star-like Mn3O4@reduced graphene oxide nanocomposites: a platform for electrochemical determination of hydrazine

Official URL: https://dx.doi.org/10.1016/j.matchemphys.2025.131710

In this study, we reported the synthesis of the Mn3O4 nanoparticles-decorated reduced graphene oxide nanocomposites (Mn3O4@RGO) serving as catalysts for the electrochemical catalytic determination of hydrazine (HZ). In this regard, Mn3O4@RGO-5, Mn3O4@RGO-10 and Mn3O4@RGO-20 nanocomposites were prepared through a one-pot solvothermal method in an ethanol/water solution (50/50, v/v) containing 1:1:5, 1:1:10 and 1:1:20 mass ratios of MnSO4, KMnO4 and graphene oxide (GO) precursors, respectively. For comparison, manganese-based nanoparticles and RGO were also synthesized in aqueous ethanol solution using the same procedure. The morphologic properties and chemical composition of the nanostructures with respect to the synthesis conditions were investigated by scanning electron microscopy (SEM), X-ray diffraction (XRD), Raman spectroscopy, Fourier transform infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS). The results demonstrated that GO used as a template in the solvothermal process had a strong effect on the crystal structures of the final manganese oxide particles. Moreover, it was determined that the mass ratios of the manganese salt precursors to GO used during the synthesis affected the structural and morphological properties of the Mn3O4@RGO nanocomposites. Namely, the presence of GO promoted the formation of Mn3O4 nanoparticles with the spinel structure, whereas its absence resulted in dominant production of MnOOH nanorods. Also, the morphology of the Mn3O4@RGO-20 nanocomposites synthesized with the highest GO mass ratio (1:1:20) was characterized by a uniform distribution of star-like Mn3O4 nanoparticles on the RGO sheets. However, Mn3O4@RGO-5 and Mn3O4@RGO-10 nanocomposites prepared with lower GO mass ratios (1:1:5 and 1:1:10) exhibited an irregular morphology tendency with agglomerated metal oxide particles. The catalytic features of glassy carbon (GC) electrodes modified with Mn3O4@RGO nanocomposites (Mn3O4@RGO/GC), MnOOH nanoparticles (MnOOH/GC) and RGO nanosheets (RGO/GC) towards electrooxidation of HZ were examined in PBS solution by electrochemical techniques. Among the modified electrodes, the Mn3O4@RGO-20/GC electrode showed excellent electrocatalytic capability towards the oxidation of HZ in PBS (pH 7.0). The electrochemical determination of HZ at the Mn3O4@RGO-20/GC electrode was evaluated using differential pulse voltammetry (DPV), and the developed sensor displayed a low detection limit (LOD) of 1.54 μΜ, a low limit of quantification (LOQ) of 5.13 μM and a high sensitivity of 0.0946 μA μM−1 cm−2. In addition, the Mn3O4@RGO-20/GC electrode exhibited good selectivity and stability in HZ measurements. The Mn3O4@RGO-20/GC electrode was also successfully applied for determination of HZ in tap water and river samples with satisfactory recoveries.