Detoxification of organophosphates using imidazole-coated Ag, Au and AgAu nanoparticles

Abstract

Organophosphate (OP) detoxification is a worldwide problem due to the high stability of P–O bonds. Here, we designed several imidazole-coated nanocatalysts targeted towards the cleavage of OP and thus their detoxification. Specifically, Ag, Au and bimetallic AgAu nanoparticles (NPs) supported on SiO₂ were functionalized with methimazole (MTZ), which comprises thiol and imidazole groups, foreseeing enabling freely available imidazole groups. Raman analyses indicate that MTZ interacts preferably via its sulfur atom over Au NPs and via the nitrogen of the imidazole ring over Ag NPs. The MTZ-derived nanocatalysts were effective towards OP cleavage. For instance, rate enhancements of 10⁸ fold were obtained for the toxic pesticide Paraoxon, compared to the uncatalyzed reaction. Interestingly, Au-derived nanocatalysts were significantly more effective since the imidazole group is free to react with the OP, which is not possible when Ag–N interactions take place.