Synergistic chemiluminescence enhancement by a MOF-derived Co₃O₄/In₂O₃ heterojunction for norepinephrine detection

The sensitive detection of norepinephrine (NE) is crucial for understanding physiological processes and diagnosing related disorders. Although chemiluminescence (CL) offers advantages such as high sensitivity and simple instrumentation, the luminol/H₂O₂ system often suffers from low catalytic efficiency. Developing high-performance, low-cost catalysts to enhance CL remains a key challenge.

In this work, a hierarchically structured Co₃O₄/In₂O₃ p-n heterojunction was constructed via a MOF-on-MOF precursor approach, in which dodecahedral Co₃O₄ nanoparticles were uniformly anchored onto In₂O₃ microtubes. Benefiting from the synergistic effect between the Co³⁺/Co²⁺ redox centers, abundant oxygen vacancies, and interfacial charge redistribution, the resulting heterostructure exhibits remarkably enhanced catalytic activity toward H₂O₂ decomposition and enhanced luminol/H₂O₂ CL by approximately 2500 folds. On this basis, a simple and sensitive flow-injection CL sensing platform was established for the quantitative detection of norepinephrine which effectively quenches the CL emission through competitive consumption of reactive oxygen species. The proposed method displays a wide linear range from 5 to 15000 nM with a low detection limit of 1.24 nM (S/N = 3). Moreover, satisfactory recoveries (97.96-103.59%) were obtained for norepinephrine determination in human serum samples, demonstrating good accuracy and practical applicability.

This work presents a novel MOF-derived p-n heterojunction strategy to synergistically enhance chemiluminescence through interfacial charge regulation and oxygen vacancy engineering. The strategy provides a robust, ultrasensitive platform for NE detection, highlighting the potential of heterojunction engineering in CL-based bioanalysis.