A colorimetric and electrochemical dual-mode Hg 2+ sensor utilizing oxidase-like activity arising from the combination of Hg 2+ and palladium metal-organic framework@graphene

Developing convenient and reliable methods for Hg monitoring is highly important. Some precious metal nanomaterials with intriguing peroxidase-like activity have been used for highly sensitive Hg detection. However, H O must be added during these detections, which impedes practical applications of Hg sensors due to its susceptible decomposition by environmental factors. Herein, we discovered that the combination of Hg and palladium metal-organic framework@graphene (Pd-MOF@GNs) exhibits oxidase-like activity (OXD). In the absence of H O , this activity not only catalyzes the oxidation of chromogenic substrates such as 3,3',5,5'-tetramethylbenzidine (TMB) or o-phenylenediamine (OPD) to produce a color change but also enhances the electrical signals during OPD oxidation. Based on these properties, an effective and convenient dual-mode colorimetric and electrochemical sensor for Hg has been developed. The colorimetric and amperometric linear relationships for Hg were 0.045 μM-0.25 mM and 0.020 μM-2.0 mM, respectively. The proposed strategy shows good recovery in real sample tests, indicating promising prospects for multiple environmental sample detection of Hg without relying on H O . The colorimetric and electrochemical dual-mode Hg sensor is expected to hold great potentials in applications such as environmental monitoring, rapid field detection, and integration into smartphone detection of Hg .