Electrochemical sensor based on the Mn3O4/CeO2 nanocomposite with abundant oxygen vacancies for highly sensitive detection of hydrogen peroxide released from living cells

Abstract

Based on the strategy of increasing the number of oxygen vacancies to improve the catalytic performance, we have developed a novel electrochemical sensor based on the multivalent metal oxides cerium dioxide and manganous oxide (Mn₃O₄/CeO₂) for reliable determination of extracellular hydrogen peroxide (H₂O₂) released from living cells. The Mn₃O₄/CeO₂ nanocomposite was characterized by high-resolution transmission electron microscopy, energy-dispersive X-ray spectroscopy, X-ray diffraction, and X-ray photoelectron spectroscopy. The electrochemical performance of the Mn₃O₄/CeO₂ nanocomposite modified glassy carbon electrode (Mn₃O₄/CeO₂/GCE) was investigated. Owing to the abundant oxygen vacancies and strong synergistic effect between the multivalent Ce and Mn, the sensor exhibited excellent catalytic activity and selectivity for the electrochemical detection of H₂O₂ with a low quantitation limit of 2 nM. Moreover, Mn₃O₄/CeO₂/GCE exhibited excellent reproducibility, repeatability, and long-term storage stability. Because of these remarkable analytical advantages, the constructed sensor was able to determine H₂O₂ released from living cells with satisfactory results. The results showed that the Mn₃O₄/CeO₂ sensor is a promising candidate for a nanoenzymatic H₂O₂ sensor with the possibility of applications in physiology and diagnosis.