Non-enzymatic hydrogen peroxide electrochemical sensor based on a three-dimensional MnO2 nanosheets/carbon foam composite

Abstract

A new type of three-dimensional electrochemical sensor platform, MnO₂ nanosheets/carbon foam (MnO₂/CF) hybrid nanostructure, was successfully fabricated for the nonenzymatic detection of H₂O₂. The morphology, structure and composition of the 3D nanostructures were systematically characterized by electron microscopy, X-ray diffraction and X-ray photoelectron spectroscopy. Uniform and thin MnO₂ nanosheets can be formed on the carbon foam after a simple chemical process by immersing the carbon foam in a KMnO₄ aqueous solution. The content of MnO₂ in the MnO₂/CF composites was found to play a great role in its sensing performance for H₂O₂ detection. The MnO₂/CF2 sample with a 24.5% MnO₂ content showed the best performance among the studied MnO₂/CF composites. The 3D hierarchical porous structure with thin MnO₂ nanosheets can provide an enhanced electrochemically active surface area, high electrical conductivity and improved analyte diffusion, which makes it a promising electrochemical sensing platform. The electrochemical studies showed that the H₂O₂ sensor based on the MnO₂/CF2 exhibited an excellent detection performance with a wide linear range from 2.5 × 10⁻⁶ to 2.055 × 10⁻³ M and a detection limit of 1.2 × 10⁻⁷ M (S/N = 3). These results demonstrate that such 3D nanocomposites have promising application in electrochemical sensors.