Morphology-tunable hollow Mn2O3 nanostructures: highly efficient electrocatalysts and their electrochemical sensing for phenolic endocrine disruptors via toughening of graphene oxide

Abstract

In the present study, three-dimensional hollow Mn2O3 polycrystals with various aggregation morphologies including spheres, dumbbells, cubes, and ellipsoids were selectively synthesized by modulating the shape of premade MnCO3 precursors with different manganese sources. Structural and electrochemical analyses demonstrated that the ellipsoidal Mn2O3 hollow structures had a higher specific surface area, wider pore diameter, and superior electron-transfer reactivity, thus, they exhibited greater electrocatalytic activity toward the oxidation of two phenolic endocrine disruptors, i.e., o-phenylphenol (OPP) and butylparaben (BP). In addition, the electro-oxidation of hollow Mn2O3 ellipsoids for OPP and BP was further enhanced when they were physically wrapped with graphene oxide (GO). This remarkable property is attributable to the dramatical increase of active sites and surface-chemisorbed oxygen species in these unique nanostructures. Highlights are presented for the simultaneous determination of OPP and BP within wide linear ranges of 0.002-20 and 0.003-24 μM, with low detection limits of 0.63 and 0.88 nM, respectively. Our findings not only offer a novel morphology-controllable synthesis strategy to better understand the morphology impact on the electrochemical performances of Mn2O3, but also represent a facile design of robust, active, and easy-to-obtain catalysts for sensors and other electrocatalytic systems.