A Novel Mimic Peroxidase Cobalt Telluride Enhanced by the Specific Binding of Hg2+ for Colorimetric and Electrochemical Dual-Mode Sensing of Hg2+ in Water

Abstract Mercury ion (Hg2+) is a highly toxic environmental pollutant distributed widely in water, posing a substantial threat to human health. Thus, developing a sensitive and handy tool for Hg2+ onsite detection will be greatly beneficial for the prevention and control of Hg2+ pollution. Herein, CoTe2 was synthesized successfully as a novel mimic peroxidase. The peroxidase-like activity of CoTe2 was significantly enhanced by Hg2+ due to the strong combination of Te–Hg, causing improved generation of ·OH and activated oxidation of the chromogenic substrate 3,3′,5,5′-tetramethylbenzidine. From this, a colorimetric and electrochemical dual-mode sensor was developed for the detection of Hg2+, which presented wide linear ranges of 0.050–10.0 and 0.010–15.0 μM, with low detection limits of 16.7 and 3.3 nM, respectively. Additionally, the sensor is more conducive to Hg2+ detection in the environmental water samples with complex compositions due to its remarkable anti-interference ability originating from the specific binding of Te–Hg. Furthermore, a smartphone was utilized as a portable tool to achieve rapid onsite detection of Hg2+. Consequently, the proposed sensor has outstanding advantages of high sensitivity, good selectivity, and high practicality, showing considerable potential for the broad application of environmental water sample detection.