Enhanced Electroactivity of Facet-Controlled Co3O4 Nanocrystals for Enzymeless Biosensing

In this work, we report enhanced electroactivity of Co3O4 nanocrystals (nanocubes, NCs and truncated nano-octahedra, TNO) on the exposed {111} facets as compared to the {001} facets in relation to the surface density and the activity of the octahedral CoIII species. Transmission electron microscopy, X-ray powder diffraction, X-ray photoelectron spectroscopy and Fourier-transform infrared spectroscopy were employed to characterize the crystal facets and materials properties. The enhanced electroactivity of {111} crystal facets was evaluated by cyclic voltammetry and amperometric titration. Our results indicate that the {111} facets in TNO has a better electroactivity for enzymeless glucose sensing with a decent glucose sensitivity of 32.54 µA (mmol/L)−1 cm−2.