Programming a triple-shelled CuS@Ni(OH)2@CuS heterogeneous nanocage as robust electrocatalysts enabling long-term highly sensitive glucose detection

The robustness of nanostructured electrocatalysts is crucial for long-term highly sensitive glucose detection, but most of the current reports mainly focus on the amelioration of activity and conductivity. Herein, we designed a triple-shelled hollow architecture by decorating the Ni(OH)2 nanocages with internal and external CuS "armors" (CuS@Ni(OH)2@CuS), aiming at boosting both electrocatalytic activity and the robustness of hollow nano-electrocatalysts. The fabrication process involves sulfidation, coordinated etching and precipitation, and template ion reutilization, which interact to give the designed catalyst a high degree of structural integrity. In this novel nano-system, the inner CuS composed of nanoparticles and the external CuS with nanoflake-like shape favored the support effect and intensified charge transfer/glucose adsorption, respectively, and provided a cooperative protection for Ni(OH)2 layer to maintain high activity and long-term glucose monitoring. Theoretical calculations further confirmed that CuS significantly promoted conductivity and glucose adsorption ability of the electrocatalyst. These advantages ensured that the proposed sensor can monitor glucose over time (60 days) combined with sensitivity up to 3128.1 μA mM–1 cm–2, wide linear range (0.001–7.6 mM), low detection limit (0.08 μM), and extremely short response time (0.75 s). Overall, this hierarchical electrocatalyst will stimulate more studies for the durability of electrochemical sensors.