Morphology engineering of NiCo2O4 enables high-efficiency electrochemical sensing of nitrite in food

Transition metal oxide of NiCo 2 O 4 as nanozyme for non-enzymatic electrochemical sensing of nitrite still needs to be explored for large scale application. In this work, a simple morphology engineering strategy of NiCo 2 O 4 has been developed for high-effciency detection of nitrite. In comparison to pristine NiCo 2 O 4 , the enhanced electrochemical sensing efficiency towards nitrite for morphology-optimized NiCo 2 O 4 were obtained. The highest enzyme-like electrocatalytic activity of NiCo 2 O 4 –0.6 was achieved by introducing 0.6 mmol CTAC in the preparation process. The constructed electrochemical sensor showed superior nitrite analytical performances of low detection limit (0.427 μM), high sensitivity (1.179 μA·μM −1 ·cm −2 and 0.073 μA·μM −1 ·cm −2 ) and wide linear response ranges (0.711–22 μM and 22–16,217 μM). In addition, the sensor was possessed of high selectivity, anti-interference, excellent reproducibility and stability. The plausible mechanism of NO 2 − oxidation into NO 3 − in the presence of NiCo 2 O 4 was proposed. More interestingly, the as-fabricated sensor displayed satisfactory recoveries (100.02%–103.21%) and relative standard deviation (RSD < 2.2%) for the detection of nitrite in real samples. Our work makes the practical application of NiCo 2 O 4 in electrochemical detection of nitrite possible and may open up a promising pathway for improving the electrochemical sensing performances of bimetallic oxide.