A novel electrochemical sensing method based on an amino-functionalized MXene for the rapid and selective detection of Hg2+

Mercury is a highly toxic element that is widely present in all types of environmental media and can accumulate in living organisms. Prolonged exposure to high levels of mercury can lead to brain damage and death, so the detection of mercury is of great importance. In this study, a cost-effective and easy-to-operate electrochemical sensing method was successfully developed based on an amino-functionalized titanium-based MXene (NH₂-Ti₃C₂T_x) for the rapid and selective detection of Hg²⁺ that could have a coordination effect with the -NH₂ group of NH₂-Ti₃C₂T_x to promote the efficient accumulation of Hg²⁺. In this strategy, the NH₂-Ti₃C₂T_x was first modified on glassy carbon electrodes (GCE) to fabricate the electrochemical sensor. Benefiting from the excellent electrical conductivity, abundant active sites, and strong adsorption capacity performance of the NH₂-Ti₃C₂T_x, the NH₂-Ti₃C₂T_x modified GCE (NH₂-Ti₃C₂T_x/GCE) exhibited satisfactory selectivity and enhanced square wave anodic stripping voltammetry (SWASV) measurement for the rapid detection of trace amounts of Hg²⁺ in aqueous solutions. The electrochemical sensor was found to be capable of detecting Hg²⁺ with a low detection limit of 8.27 nmol L^-1 and a linear range of 0.5 μmol L^-1 to 50 μmol L^-1. The response time of the electrochemical sensing method was 308 s. In addition, the electrochemical sensing method has good selectivity, repeatability and stability, and multiple heavy metal ions have no effect on its detection, with repeatability and stability RSDs of 1.68% and 1.43%, respectively. Furthermore, the analysis of practical water samples demonstrated that the developed method was highly practical for the actual determination of Hg²⁺ with recoveries in the range of 99.22-101.90%.