To achieve ultrasensitive electrochemical detection of mercury ions employing metallic 1T-MoS2 nanosheets

•Selective electrochemical detection of mercury ions was achieved based on the high affinity between Hg and S atoms.•Using phase engineering strategy can largely reduce charge transfer resistance of MoS2.•The reduction of charge transfer resistance remarkably improves the sensitivity and lowers the limit of detection. The establishment of analytical methods with superior sensitivity, selectivity, accuracy, and stability, as well as ultralow detection limits inspired a broad range of research enthusiasm. In this work, we developed an electrochemical method for detecting mercury ions using metallic 1T-MoS2 nanosheets, which was firstly fabricated using phase engineering strategy and then exfoliated. Remarkably promoted sensitivity and significantly lowered limits of detection (LODs) were achieved due to the dramatically reduced charge transfer resistance of 1T-MoS2 nanosheets compared with that of the semiconducting 2H-MoS2 nanoflakes. After electrode modification and optimization, working curves for both two materials were obtained. Astonishingly, the LODs of 1T-MoS2 modified glassy carbon electrodes (GCEs) was calculated to be 1.54 × 10−19 M (DL = 3σ/k), which was six orders of magnitude lower than that of 2H-MoS2 (1.46 × 10−13 M). And 1T-MoS2-based electrochemical detection method also exhibited superior selectivity towards other ten ions selected because of the high affinity between Hg and S. The stability and reproducibility of the new method was impressive as well, and the recovery rates using spiked real water samples were all in the range of 99.8–101.2% due to the superb sensitivity. All results proved that the metallic 1T-MoS2 nanosheets a promising material for electrochemical detection of mercury ions. [Display omitted]