Graphene wrapped porous Co₃O₄/NiCo₂O₄ double-shelled nanocages with enhanced electrocatalytic performance for glucose sensor

Graphene (G) wrapped porous Co₃O₄/NiCo₂O₄ double-shelled nanocages (Co₃O₄/NiCo₂O₄ DSNCs@G) were prepared by the formation of Co₃O₄/NiCo₂O₄ DSNCs using zeolite imidazole frameworks-67 as template with the subsequent calcination and package of G by hydrothermal method. The abundant accessible active sites provided by the porous structure of Co₃O₄/NiCo₂O₄ DSNCs and efficient electron transport pathways for electrocatalytic reaction offered by the high conductive G worked very well together in a ferocious synergy, which endowed Co₃O₄/NiCo₂O₄ DSNCs@G with excellent electrocatalytic behaviors for determining glucose. A comparison between Co₃O₄/NiCo₂O₄ DSNCs without G packing and Co₃O₄/NiCo₂O₄ DSNCs@G showed that former had linear response window concentrations of 0.01-3.52 mM (correlation coefficient = 0.999), detection limit of 0.744 μM (S/N = 3) and sensitivity of 0.196 mA mM⁻¹ cm⁻², whereas the latter exhibited linear response window concentrations of 0.01-3.52 mM (correlation coefficient = 0.999), detection limit of 0.384 μM (S/N = 3) and sensitivity of 0.304 mA mM⁻¹ cm⁻². The combination of Co₃O₄/NiCo₂O₄ DSNCs and G was a meaningful strategy to fabricate high-performance non-enzyme glucose sensors with low detection limit, good selectivity and high sensitivity.