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[Display omitted] • Near-spherical ZnO/N-rGO nanocomposite was prepared by a facile hydrothermal method. • Systematic study of electrochemical sensing property of ns-ZnO/N-rGO for nitrite. • Sensor was used for detection of nitrite in ham sausage, pickle and tap water. • The electrochemical sensing mechanism of ns-ZnO/N-rGO for nitrite was explored. A hierarchical near-spherical ZnO (ns-ZnO)/Nitrogen-doped reduced graphene oxide (N-rGO) nanocomposite was synthesized via a facile hydro/solvo-thermal route. Then, a non-enzymatic nitrite electrochemical sensor (ns-ZnO/N-rGO/GCE) was obtained by modifying glassy carbon electrode (GCE) with the prepared nanocomposite. More adsorption sites and electro-catalytic active sites were provided at the electrode interface thanks to the formation of hierarchical structure, making the fabricated GCE possess a remarkable amperometric sensing property for nitrite. The limit of detection (LOD) was as low as 0.08 μM, and the detection range was as broad as 0.037 μM–5.9 mM. Furthermore, this sensor showed satisfactory recovery for nitrite in genuine samples including ham sausage, pickle and tap water, suggesting the potential practical application performance of ns-ZnO/N-rGO/GCE in the fields of food analysis and environmental monitoring. [ABSTRACT FROM AUTHOR]

• Six ZnO materials with different morphology were synthesized by controlling solvent. • Practical application of stir bar-shaped ZnO/Nafion/GCE sensor for nitrite detection in water, ham, pickle. • A dependency between ZnO's sensing property and its morphology was revealed. • Study of ZnO's sensing mechanism for detecting nitrite. Excessive uptake of food or drinking water which is rich in nitrite has been demonstrated to be very hazardous to both the health of humans and animals, so it is of great significance to develop a reliable technique for low-concentration detection of nitrite. Herein, we reported the synthesized zinc oxide which is an excellent electrochemical material for the sensing of nitrite. Interestingly, the ZnO material exhibits a strong dependent relationship between the electrochemical sensing performance and its morphology controlled by the solvent employed in the solvo-thermal method. In particular, the stir-bar shaped ZnO nanorods, with a 40∼90 nm width and 50∼170 nm length, display significantly improved electrocatalytic performance to the electrochemical oxidation of nitrite which is benefited from the more reactive active sites based on the higher dispersion and smaller size. The sensor based on ZnO/Nafion modified glassy carbon electrode (ZnO/Nafion/GCE) shows a broad linear response within the range of 0.3 μM∼6.14 mM and 0.8 μM∼4.86 mM, respectively, for amperometry and linear sweep voltammetry (LSV), the corresponding limit of detection (LOD) were calculated to be 0.21 μM and 0.62 μM, respectively. Also the prepared sensor shows excellent sensitivity, reproducibility, stability and high anti-interference abilities. More importantly, the satisfactory recovery is obtained from ham sausage, pickle and running water, demonstrating the great application prospects of this sensor. In addition, the sensing mechanism of such ZnO sensing to nitrite is also discussed in detail. [ABSTRACT FROM AUTHOR]