Hetero-structured MnO-MnO@rGO composites: Synthesis and nonenzymatic detection of HO.

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-MnO microparticles wrapped by reduced graphene oxide (MnO-MnO@rGO) were synthesized through a facile solvothermal-calcination treatment. The morphology and structure of MnO-MnO@rGO were characterized by scanning electron microscopy, transmission electron microscopy, X-ray photoelectron spectroscopy, Raman spectroscopy, and X-ray diffraction. The as-synthesized MnO-MnO@rGO exhibited prominent catalyzing effect on the electroreduction of HO, due to the combination of good electrical conductivity of rGO and the synergistic effect of MnO and MnO. The MnO-MnO@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 cm. The proposed sensor displayed noticeable selectivity and long-term stability. In addition, the biosensor has been successfully applied for detecting HO in tomato sauce with good recovery, revealing its promising potential applications for practical electrochemical sensors.