Engineering the valence state of ZIF-67 by Cu2O for efficient nonenzymatic glucose detection.

The valence state regulation of Co-based electrocatalysts is extremely important and greatly challenging to enhance the electrochemical performance toward glucose oxidation. Herein, Cu2O@ZIF-67 composites with fine-tuned valence states were rationally constructed for boosting glucose oxidation. X-ray photoelectron spectroscopy (XPS) and cyclic voltammetry (CV) analysis confirm that the content of the high valence state Co (Co3+) in Cu2O@ZIF-67 is much higher than that in the individual ZIF-67 due to the synergistic effects between ZIF-67 and Cu2O. As a result, Co3+-rich Cu2O@ZIF-67 composite exhibits remarkable activity toward glucose electro-oxidation with two linear response ranges of glucose concentration, from 0.01 to 10 mM and 10 to 16.3 mM, high sensitivities of the linear ranges (307.02 and 181.34 μA mM-1 cm-2) as well as a low detection limit (6.5 μM). This research provides a novel avenue for the progress of highly efficient electrocatalysts for nonenzymatic glucose oxidation.