Oxygen vacancy confined nickel cobaltite nanostructures as an excellent interface for the enzyme-free electrochemical sensing of extracellular H2O2 secreted from live cells

Abstract

Oxygen vacancy (O_V) manufacturing is an effective way to boost the efficiency of a catalyst; therefore, the development of O_V-rich catalysts has attracted substantial research interest. Herein, the authors report the engineering of highly efficient NiCo₂O₄ nanostructures (O_V–NCO) with plentiful oxygen vacancies. The presence of O_V was confirmed by X-ray photoelectron microscopy (XPS) and electron spin resonance spectroscopy (ESR). Impedance analysis confirmed that oxygen vacancy manufacturing in the NCO lattice meaningfully promotes the interfacial electron transferability. As a result, O_V–NCO could deliver improved electrocatalysis significantly. Furthermore, O_V–NCO was used to fabricate a highly efficient and dependable nonenzymatic electrochemical H₂O₂ detector that achieved excellent sensing performance owing to the oxygen vacancy richness, high specific surface area and synergistic effects of O_V–NCO. The sensor not only exhibited a wide linear response (26–6.6 mM) with a nanomolar limit of detection (9 nM) but also a high selectivity for H₂O₂. The practicability of this resultant sensor was verified by real-time monitoring of H₂O₂ release from RAW 264.7 cells, confirming the potential application of this biosensor in clinical analysis.