Abstract
MoS&sub2; quantum dots (QDs) functionalized g-C&sub3;N&sub4; nanosheets (MoS&sub2;@CNNS) were prepared through a protonation-assisted ion exchange method, which were developed as a highly efficient biomimetic catalyst. Structural analysis revealed that uniformly-dispersed MoS&sub2; QDs with controllable size and different loading amount grew in-situ on the surface of CNNS, forming close-contact MoS&sub2;@CNNS nanostructures and exhibiting distinct surface properties. Compared to MoS&sub2; QDs and CNNS, the MoS&sub2;@CNNS nanocomposites exhibited a more than four times stronger peroxidase-like catalytic activity, which could catalyze the oxidation of 3,3',5,5'-tetramethylbenzidine (TMB) in the presence of H&sub2;O&sub2; to generate a blue oxide. Among the MoS&sub2;@CNNS nanocomposites, MoS&sub2;@CNNS(30) was verified to present the best intrinsic peroxidase-like performance, which could be attributed to the more negative potential and larger specific surface area. A simple, rapid and ultrasensitive system for colorimetric detection of H&sub2;O&sub2; was thus successfully established based on MoS&sub2;@CNNS, displaying nice selectivity, reusability, and stability. The detection limit of H&sub2;O&sub2; could reach as low as 0.02 μM. Furthermore, the kinetic and active species trapping experiments indicated the peroxidase-like catalytic mechanism of MoS&sub2;@CNNS. This work develops a novel, rapid, and ultrasensitive approach for visual assay of H&sub2;O&sub2;, which has a potential application prospect on clinical diagnosis and biomedical analysis.