Enhanced oxidase-like activity of Ag@Ag2WO4 nanorods for colorimetric detection of Hg2+

Abstract In this paper, four kinds of Ag2WO4 materials were synthesized via facile hydrothermal methods, which were developed as highly efficient biomimetic catalysts for the first time. These Ag2WO4 materials exhibited distinct oxidase-like activities owing to their different crystal structures, morphologies and surface properties. Among them, Ag@Ag2WO4 nanorods (AWNRs-9) exhibited the best intrinsic oxidase mimetic performance, which were composed of Ag nanoparticles (NPs) loading on the surface of Ag2WO4 nanorods (NRs). It is found that the introduction of Ag NPs can significantly enhanced the oxidase-like catalytic activity due to the synergistic effect between Ag NPs and Ag2WO4 NRs. In addition, the catalytic oxidation reaction of 3,3’,5,5’-tetramethylbenzidine by AWNRs-9 was dramatically and selectively enhanced due to the mercury-stimulated effect. Thus, a simple, rapid and sensitive method for colorimetric detection of Hg2+ was developed, displaying a good linear response in the range of 0.25 µM to 8.0 µM with a detection limit of 1.6 nM. This assay method also showed a high selectivity, good stability and favorable practicability. It was successfully applied to the detection of Hg2+ in real water samples. This sensing system is expected to hold bright prospects for quantitative detection of Hg2+ in biological, environmental, and food fields.