Mimetic peroxidase based on a gold amalgam for the colorimetric sensing of trace mercury(II) in water samples

The development of an efficient protocol to achieve the precise monitoring of trace Hg2+ is of great significance. In this work, a colorimetric sensing platform for Hg2+ monitoring was constructed via modifying gold nanoparticles (Au NPs) and hemin/reduced graphene oxide (H-rGO) onto carbon cloth (CC) (AuNPs/H-rGO/CC). The Au NPs, anchored on the surface of the interlaced fibers of CC without aggregation, showed high peroxidase-mimetic catalytic activity. The formed Au amalgam and the synergistic effect of Au NPs and H-rGO enhanced the peroxidase-mimetic activity of AuNPs/H-rGO/CC and enabled the sensing platform to achieve the colorimetric detection of Hg2+ over a wide range of 3.2 × 10−10 M–1.0 × 10−6 M. AuNPs/H-rGO/CC exhibited high selectivity towards Hg2+ due to the high special affinity between Au NPs and Hg2+. The sensing platform was further successfully applied to the determination of Hg2+ in different water samples via a simplified operation involving just tweezers. The present sensing protocol is expected to provide an efficient way to construct colorimetric sensors and to promote the sensitive determination of Hg2+ for a variety of relevant applications.