2D CTAB-MoSe2 Nanosheets and 0D MoSe2 Quantum Dots: Facile Top-Down Preparations and Their Peroxidase-Like Catalytic Activity for Colorimetric Detection of Hydrogen Peroxide.

We report the facile and economic preparation of two-dimensional (2D) and 0D MoSe2 nanostructures based on systematic and non-toxic top-down strategies. We demonstrate the intrinsic peroxidase-like activity of these MoSe2 nanostructures. The catalytic processes begin with facilitated decomposition of H2O2 by using MoSe2 nanostructures as peroxidase mimetics. In turn, a large amount of generated radicals oxidizes 3,3,5,5-tetramethylbenzidine (TMB) to produce a visible color reaction. The enzymatic kinetics of our MoSe2 nanostructures complies with typical Michaelis-Menten theory. Catalytic kinetics study reveals a ping-pong mechanism. Moreover, the primary radical responsible for the oxidation of TMB was identified to be Ȯ2- by active species-trapping experiments. Based on the peroxidase mimicking property, we developed a new colorimetric method for H2O2 detection by using 2D and 0D MoSe2 nanostructures. It is shown that the colorimetric sensing capability of our MoSe2 catalysts is comparable to other 2D materials-based colorimetric platforms. For instance, the linear range of H2O2 detection is between 10 and 250 μM by using 2D functionalized MoSe2 nanosheets as an artificial enzyme. Our work develops a systematic approach to use 2D materials to construct novel enzyme-free mimetic for a visual assay of H2O2, which has promising prospects in medical diagnosis and food security monitoring.