Enzyme-like activity of cobalt-MOF nanosheets for hydrogen peroxide electrochemical sensing

Abstract

[EN] Metal-organic frameworks (MOFs) are receiving increased attention as new functional nanomaterials for the development of electrochemical sensors. Herein, we develop an electrochemical platform for non-enzymatic hydrogen peroxide detection built with a composite of two-dimensional cobal t MOF nanosheets and Nafion (2D-Co-MOF@Nafion). The feasibility of the 2D-Co-MOF@Nafion composite as active material for high perfor-mance hydrogen peroxide sensor was investigated by usin g cyclic voltammetr y and chronoamperometry. Its voltammetric response reveals an efficient charge transport through the MOF composite, and rapid electron exchange between MOF and electrode. Notably, these MOF nanosheets exhibit enzyme-like activity for the non-common catalytic oxidation of hydrogen peroxide, leadin g to an electrochemical sensor with rapid quantitative detection, outstanding sensitivity, selectivity, stability, and durability at the desirable neutral pH. In particular, for a cobal t metal loading of 1.2 nanomol, the sensor yields amperometric H2O2 detection with characteristic electrocatalytic parameters ofima x = 5.7 mA cm(-2)andKM= 13 mM. Moreover, linear ranges of up to either 1 mM or 10 mM are achieved, with sensitivities as high as 570 +/-; 5 A cm(-2) mM(-1) or 395 +/- 10 A cm(-2) mM(-1) for the low and high concentration ranges, respectively. The particular coordination chemistr y of the MOF consisting of a regular arrangement of multiple Co(II) redox metal sites connected by appropriate organic ligands can provide inherent enzyme-mimicking properties, thereby explaining the higher oxidase-like activit y of the present MOF. This work raises the new idea of using two-dimensional cobalt-based MOFs as active nanozymes, offering exciting opportunities in the design of non-enzymatic electrochemical sensing devices.