Surface‐Nitrided Ni@Ni ₃ N/NCNTs Heterostructures for Sensitive and Portable Nonenzymatic Glucose Detection

A heterostructured Ni@Ni ₃ N/NCNTs electrocatalyst was rationally designed via a MOF‐derived strategy combined with controlled surface nitridation to achieve highly efficient nonenzymatic glucose sensing. In this architecture, metallic Ni nanoparticles anchored on a three‐dimensional N‐doped carbon nanotube framework were selectively converted into a thin Ni ₃ N surface layer, forming abundant Ni/Ni ₃ N heterointerfaces while preserving a conductive Ni core. Electrochemical studies reveal that the engineered heterointerfaces significantly reduce charge‐transfer resistance and increase electrochemically active surface area, thereby promoting the generation of NiOOH species and facilitating glucose oxidation. As a result, the Ni@Ni ₃ N/NCNTs electrode exhibits a high sensitivity of 685.07 μA mM ⁻¹ cm ⁻² , a low detection limit of 0.34 μM, and a wide linear range of 1–7000 μM for nonenzymatic glucose detection. Furthermore, integration with a smartphone‐enabled electrochemical platform enables portable and real‐time glucose analysis, demonstrating the strong potential of this surface‐engineered heterostructure for practical portable sensing applications.