Hetero-structured MnO-Mn₃O₄@rGO composites: Synthesis and nonenzymatic detection of H₂O₂

The construction of metal-oxide heterojunction architecture has greatly widened applications in the fields of optoelectronics, energy conversions and electrochemical sensors. In this study, olive-like hetero-structured MnO-Mn₃O₄ microparticles wrapped by reduced graphene oxide (MnO-Mn₃O₄@rGO) were synthesized through a facile solvothermal-calcination treatment. The morphology and structure of MnO-Mn₃O₄@rGO were characterized by scanning electron microscopy, transmission electron microscopy, X-ray photoelectron spectroscopy, Raman spectroscopy, and X-ray diffraction. The as-synthesized MnO-Mn₃O₄@rGO exhibited prominent catalyzing effect on the electroreduction of H₂O₂, due to the combination of good electrical conductivity of rGO and the synergistic effect of MnO and Mn₃O₄. The MnO-Mn₃O₄@rGO modified glassy carbon electrode provided a wide linear response from 0.004 to 17 mM, a low detection limit of 0.1 μM, and high sensitivity of 274.15 μA mM^-1 cm^-2. The proposed sensor displayed noticeable selectivity and long-term stability. In addition, the biosensor has been successfully applied for detecting H₂O₂ in tomato sauce with good recovery, revealing its promising potential applications for practical electrochemical sensors.