PVP-capped Pt NPs-depended catalytic nanoprobe for the simultaneous detection of Hg2+ and Ag+

Mercury ions (Hg2+) and silver ions (Ag+) are assigned to the highest toxicity class of heavy metal pollution. Here, a novel sensor is firstly developed for the simultaneous detection of coexisting Ag+ and Hg2+ in aqueous solution, depending on the catalytic properties of poly(vinyl pyrrolidone) (PVP)-capped platinum nanoparticle (Pt NPs) and the strong chelation of EDTA to Hg2+. PVP-capped Pt NPs exhibit uniform morphology and possess great intrinsic peroxidase-like activity in comparison to citrate-capped Pt NPs, PVP-capped Ru NPs and Ir NPs, attributing to the enhanced catalytic efficiency determined by loosely packed PVP and the excellent catalytic decomposition activities of H2O2. Hg2+ and Ag+ could induce remarkable inhibition of the peroxidase-like activity of Pt NPs by changing the electronic state of the active sites through metallophilic interactions. The selective and simultaneous detection of Hg2+ and Ag+ was realized via the addition of ethylenediaminetetraacetate (EDTA), which could successfully mask Hg2+ but had negligible effect on Ag+. The proposed approach inspires new designs of novel catalytic nanoprobes for the multi-analyte assay of heavy metal ions.