Spinel CuCo2O4 Microflowers with Highly Exposed High-Index (112) Facets for Electrocatalytic Glucose Oxidation

The design of nanomaterials enclosed by high-index facets plays a critical role in the surface-sensitive properties. Herein, hierarchical CuCo2O4 microflowers (CCO-F) with highly exposed high-index (112) facets are rationally designed via a solvothermal method followed by calcination. CCO-F are composed of 30 nm-thick nanoflakes and have an ultrahigh specific surface area of ca. 205.48 m2 g-1. Additionally, nanoparticle-assembled CuCo2O4 microspheres (CCO-S) are prepared, and these nanoparticles are partly enclosed by the (110) facets. Abundant octahedrally coordinated Co3+ (Co3+ Oh) and tetrahedrally coordinated Cu2+ (Cu2+ Td) exist in the (112) facet, especially Co3+ Oh (with a density of 0.063 & Aring;-2); moreover, the (112) facet possesses a high surface Gibbs free energy (2.7367 J m-2). Therefore, CCO-F have significant advantages of adsorbing glucose and conducting the subsequent redox reactions. In addition, the hierarchical microstructure promotes the reaction kinetics of CCO-F. Benefiting from these features, the CCO-F-modified electrode exhibits high sensitivities (1351.2 and 598.7 mu A mM-1 cm-2), wide linear ranges (1 mu M-3 mM and 4-10 mM), rapid response time, low detection limit, excellent stability, and good selectivity. This work indicates that the exposure of a high percentage of high-index facets is an effective approach to exploring high-performance electrocatalysts for glucose detection.