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 Å–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 μA mM–1 cm–2), wide linear ranges (1 μM–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.