Encapsulation of Glucose Oxidase on Zeolitic Imidazolate Framework-67 Collaborates with Carbon Nanotubes to Enhance the Electrochemical Performance of the Enzymatic Electrode

Enzyme biofuel fuel cell (EBFC) is a green energy device that converts biological energy into electric energy effectively through the interaction of an enzyme and substrate. However, a low electron transfer (ET) rate and enzyme activity affect the performance of EBFC. Herein, we successfully encapsulated glucose oxidase (GOx) in zeolitic imidazolate framework-67 (ZIF-67) to form ZIF-67@GOx. Compared with ZIF-67-GOx based on the adsorption method, the embedding method not only increased the GOx load but also protected the GOx from environmental damage and improved the heat resistance and recyclability of the GOx. Furthermore, ZIF-67@GOx was combined with carbon nanotube (CNT) to construct an enzyme electrode based on GCE. The electrochemical performance of as-synthesized CNT/ZIF-67@GOx was analyzed by cyclic voltammetry (CV), electrochemical impedance spectroscopy, and linear sweep voltammetry. The proportions of CNT and ZIF-67@GOx of 1:5 obtained the optimal electrochemical performance. The ET constant (K_s) of the CNT/ZIF-67@GOx reached 6.2 s^-1, which is 2.6 times that of CNT/ZIF-67-GOx. This proposed strategy based on the ZIF-6 material embedding will facilitate the construction of efficient enzyme electrodes.