Pt–Se nanostructures with oxidase-like activity and their application in a selective colorimetric assay for mercury(II)

Abstract

In this paper, platinum (Pt)–selenium (Se) nanostructures and Pt nanoparticles were synthesized by a facile one-step chemical reduction route and their catalytic performance was evaluated as oxidase mimic. The results of structure characterization revealed that Pt–Se nanostructures consist of Pt and Se atoms (the Pt/Se atomic molar ratio is approximately 7:3), while Pt nanoparticles consist of pure element Pt. The oxidase-like activity of Pt–Se nanostructures and Pt nanoparticles was evaluated with 3,3′,5,5′-tetramethylbenzidine (TMB) as substrate. The results indicated that Pt–Se nanostructures had a lower Michaelis constant (K m) and higher catalytic constant (K cat) for TMB oxidation than that of Pt nanoparticles,which mean the binary Pt–Se hybrid nanostructures had stronger binding affinity with TMB and higher catalytic activity in comparison with monometallic Pt nanoparticles. The enhanced oxidase-like activity of Pt–Se nanostructures may be due to element Se doped in binary Pt–Se hybrid nanostructures, which can accelerate electron transport and provide excellent chemical stability against catalytic performance degradation during the TMB oxidation reaction. Mercury (II) ions (Hg2+) could inhibit the oxidase mimetic activity of Pt–Se nanostructures and resulted in a color change of the reaction system. Based on this mechanism, a facile colorimetric assay for Hg2+ was developed with a detection limit as low as 70 nm and a linear range of 0–2.5 μM.