Accelerated reconstruction of ZIF-67 with significantly enhanced glucose detection sensitivity

Abstract

Research on metal-organic framework (MOF)-based non-enzymatic glucose sensors usually ignores the impact of the surface reconstruction degree of MOF on the activity of catalyzing glucose oxidation. In this work, we choose zeolitic imidazolate framework-67 (ZIF-67), which is commonly used in glucose sensing, as a representative to investigate the influence of reconstruction degree on its structure and glucose catalytic performance. By employing the electrochemical activation strategy, the activity of ZIF-67 in catalyzing glucose gradually increased with the prolongation of the activation time, reaching the optimum after 2 h activation. The detection sensitivity of the activated ZIF-67 was 19 times higher than that of the initial ZIF-67, and the limit of detection (LOD) was lowered from 7 to 0.4 µM. Our findings demonstrate that the oxidation degree of ZIF-67 deepened rapidly with continuously activation and was basically reconstructed to CoOOH after 2 h activation, accompanied by a morphological change from cuboctahedral to flower-like. Simultaneously, theoretical investigation revealed that ZIF-67 is not suitable as a stable glucose sensor electrode since the adsorbed glucose molecules hasten the dissociation of ligands and the breaking of Co–N bond in ZIF-67. Therefore, our work has important implications for the rational design of next-generation MOF-based glucose sensors.