An environmentally friendly, layer-by-layer assembled electrode for ultrafast electrochemical detection of nitrite in water

The development of sensors for rapid nitrite detection in water is of great significance to human health and environmental protection. In this study, carboxylated cellulose nanocrystals were prepared by oxidizing microcrystalline cellulose with ammonium persulfate. Subsequently, a composite film was successfully prepared by depositing carboxylated nanocrystalline cellulose and poly(diallyldimethyl ammonium chloride) onto a glass carbon electrode using the layer-by-layer assembly method. After electrodepositing poly(3,4-ethylenedioxythiophene), the resulting electrode was utilized as an electrochemical sensor for nitrite detection. The effect of the number of layers of the composite film on electrocatalytic performance towards nitrite was investigated. Under optimal conditions, the sensor exhibited an ultrafast response to nitrite within 0.5 s, which was better than that of most similar sensors reported. Additionally, it had a wide linear range of 0.5–3000 µM and a low detection limit of 0.26 µM. Furthermore, this sensor showed satisfactory recovery between 98.78 and 103.29% for nitrite in real water samples. Our study presents a significant approach towards the development of an environmentally friendly nitrite sensor with an ultrafast response. Graphical abstract