Mercury(II)‐Triggered Oxidase‐Like Activity of CoSe ₂ @Au NPs for Dual‐Mode Detection in Food

Owing to the strong and selective coordination with Hg 2+ , the high‐stable gold‐anchored cobalt selenide nanomaterials (CoSe 2 @Au NPs) were prepared via multi‐step wet chemical synthesis method for the dual‐mode sensing of Hg 2+ in food samples. The interplay between the 3d orbital of Co and the 6s orbital of Hg can enhance the binding ability of Se for Hg 2+ , as well as Au also has an amalgamation tendency. The Hg 2+ can act as an electron acceptor and extracts electrons from the Au and Se atoms, resulting in the lack of electrons at the surface, subsequently promoting the partial reduction of some Co 3+ to Co 2+ . Thus, oxidase‐like activity of CoSe 2 @Au NPs can be triggered via the adsorption with Hg 2+ . Within the Hg 2+ concentration scope of 0.05–7.00 µmol/L, the dual‐mode sensor exhibits a linear response to Hg 2+ with a low LOD of 0.013 µmol/L for colorimetric and 0.032 µmol/L for photo‐thermal. Besides, the prepared dual‐mode sensor can show a good recovery for the detection in food samples (90.00%–111.00%).