A facile label-free colorimetric sensor for Hg2+ based on Hg-triangular silver nanoplates with amalgam-like structure

In this contribution, we have developed a rapid method for the highly selective detection of mercury ions (Hg 2+ ) using citrate-stabilized triangular silver nanoplates (AgNPs). The colorimetric sensor strategy is based on the aggregation of Hg 2+ -coated AgNPs with the assistance of two amino groups of lysine, resulting in a color change of AgNP solution from blue to mauve or gray. The sensor enables the analysis of Hg 2+ with a minimum detectable concentration that corresponds to 50   nM. Meanwhile, the strategy offers excellent selectivity toward Hg 2+ against other cations. The validation of this method is carried out by analysis of Hg 2+ in tap water with satisfying recoveries over 91.35–106%.