Highly sensitive enzyme-free amperometric sensing of hydrogen peroxide in real samples based on Co3O4 nanocolumn structures

Abstract

Developing a non-noble metal nanostructure based highly active nanocatalyst for sensitive detection of small molecules is of great interest due to its large active surface area and rapid catalytic activity towards analytes. In this work, we demonstrate the synthesis of porous cobalt oxide nanocolumn arrays (Co₃O₄ NCs) and explore them as an efficient catalyst material for electrochemical determination of hydrogen peroxide (H₂O₂) in real samples (river water and antiseptic solutions). The morphology and crystalline properties of the as-synthesized Co₃O₄ NC structures are characterized by using scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), and electrochemical methods. Unlike Co₃O₄ nanoparticles (Co₃O₄ NPs), the Co₃O₄ NCs show significantly higher sensing performance towards the electrochemical reduction of H₂O₂ in 0.1 M NaOH solution. The presence of nanoporous structures in Co₃O₄ NCs could provide a large specific surface area, higher conductivity and rapid analyte diffusion, which makes them a promising candidate for detection of H₂O₂. The amperometric analysis shows that Co₃O₄ NCs exhibited a faster electrocatalytic response towards a wide concentration range of H₂O₂ (100 to 2000 μM) with the lowest limit of detection (LOD) of 0.28 μM (S/N = 3). The Co₃O₄ NC electrode is highly selective for detecting H₂O₂ in the presence of major important biomolecules such as glucose, ascorbic acid, uric acid, dopamine, and other anionic interfering compounds. These results demonstrate that Co₃O₄ NCs serve as a potential sensing platform towards the electrochemical detection of small molecules.