The ultrathin palladium nanosheets for sensitive and visual Hg2+ detection in the food chain

The detection of mercury, one of the ten most dangerous chemicals, is significant to provide helpful information for assessing mercury toxicity and health risks. However, it is a challenge to explore simple, sensitive, accurate, and cheap Hg2+ detection methods. Noble metal nanomaterials are used for Hg2+ detection by the colorimetric method widely. Still, the pure noble metal materials’ detection limit of Hg2+ is high, and sensitivity enhancement usually requires further complex modification. Here, we use a facile one-step route to synthesize ultra-thin two-dimensional palladium nanosheets (PdNS), which have high selectivity and sensitivity for Hg2+ detection by colorimetric method with a low detection limit (0.55 ppb). The detection of Hg2+ by PdNS involves multiple mechanisms, including the formation of amalgam and PdO to improve the peroxidase-mimic activity of PdNS and PdNS motor function to increase its collision probability with the detection reactant. The PdNS can be used to detect Hg2+ in various actual samples. The detection results are highly consistent with the data obtained by the atomic fluorescence spectrometer (AFS). Then, we developed a Hg2+ detection kit, which can realize simple, sensitive, and accurate Hg2+ detection by naked eye or cellphone at a meager cost (0.3 dollars each sample).