Fast and Continuous Synthesis of NiCo2(OH)x Nanosheet Precursor in Preparation of NiCo2O4 Nanorod Networks for Glucose Sensing

It is still a challenge to prepare nanomaterials with desired structure and properties on a large scale. This research aims to develop a method for synthesis of NiCo₂O₄ nanorod networks for their potential application in glucose sensors. NiCo₂(OH)_x nanosheets are prepared continuously by using a static mixer as a tubular reactor. The formation of NiCo₂(OH)_x nanosheets is completed within 5 s, resulting in a high yield of 0.1 g/min. The NiCo₂(OH)_x nanosheets convert to NiCo₂O₄ polycrystalline nanorod networks through sintering at 450 °C. The NiCo₂O₄ nanorods have abundant Ni(II)/Ni(III) and Co(II)/Co(III) active sites, which enhance the electrochemical performance and have great application in glucose sensors. The NiCo₂O₄-based glucose sensors have a sensitivity of 1442 μA mM^–1 cm^–2, a low limit of detection of 0.6 μM, and a wide linear range of 1.8 μM to 2 mM at an applied potential of 0.65 V (vs Hg/HgO). The sensors also exhibit excellent selectivity against common interferents (ascorbic acid, dopamine, etc.) and retained 85% activity after 30 days. The glucose sensors show high reliability in monitoring the real human serum samples.