Interfacial Engineering of Hierarchical Transition Metal Oxide Heterostructures for Highly Sensitive Sensing of Hydrogen Peroxide

Hydrogen peroxide (H 2 O 2 ) is a major messenger molecule in cellular signal transduction. Direct detection of H 2 O 2 in complex environments provides the capability to illuminate its various biological functions. With this in mind, a novel electrochemical approach is here proposed by integrating a series of CoO nanostructures on CuO backbone at electrode interfaces. High‐resolution transmission electron microscopy (HRTEM), X‐ray diffraction, and X‐ray photoelectron spectroscopy demonstrate successful formation of core–shell CuO–CoO hetero‐nanostructures. Theoretical calculations further confirm energy‐favorable adsorption of H 2 O 2 on surface sites of CuO–CoO heterostructures. Contributing to the efficient electron transfer path and enhanced capture of H 2 O 2 in the unique leaf‐like CuO–CoO hierarchical 3D interface, an optimal biosensor‐based CuO–CoO‐2.5 h electrode exhibits an ultrahigh sensitivity (6349 µA m m −1 cm −2 ), excellent selectivity, and a wide detection range for H 2 O 2 , and is capable of monitoring endogenous H 2 O 2 derived from human lung carcinoma cells A549. The synergistic effects for enhanced H 2 O 2 adsorption in integrated CuO–CoO nanostructures and performance of the sensor suggest a potential for exploring pathological and physiological roles of reactive oxygen species like H 2 O 2 in biological systems.