Mesoporous ZnCo₂O₄ nanowire arrays with oxygen vacancies and N-dopants for significant improvement of non-enzymatic glucose detection

An efficient electrode for use in a sensitive, nonenzymatic catalyst for electro-oxidation of glucose is urgently needed to reduce the cost of regular diabetic monitoring. Finding a way to improve sensitivity while reserving the catalytic activity for glucose monitoring presents a big challenge. Replacing oxygen defects with nitrogen atoms in a nanostructured transition metal oxide can expose more catalytic active sites with improved electrical conductivity. Herein, a simple and scalable technique has been demonstrated to fabricate N-doped mesoporous ZnCo₂O₄ nanowire arrays (N-doped ZnCo₂O₄ electrode) through NH₃-plasma treatment toward high-performance nonenzymatic glucose sensors. As a result, an N-doped ZnCo₂O₄ electrode exhibits ultra-sensitivity of 14,000 μA·mM⁻¹ cm⁻², a detection limit of 0.54 μM (S/N = 3), and a short response time of about 7.9 s. The impressive electrocatalytic performance originates from the filling of oxygen vacancies with nitrogen atoms in the mesoporous ZnCo₂O₄ nanowire arrays, which helps to accelerate the kinetics by increasing the pre-oxidation state of Co³⁺ and improving the electrical conductivity. Therefore, this study provides new insights into investigating the rational design of nanostructured transition metal oxides/hydroxides with tunable active sites and electrical conductivities for high-performance non-enzymatic glucose sensors.