Mechanism and Dependences of MXene-Based Electrochemical Detection of Cadmium Ions

The industrial use of cadmium and other heavy metals generates significant waste that pollutes the environment [1]. Cadmium can adversely affect various systems within the human body, making its detection in the environment essential for ensuring public health. One effective approach to detecting pollutants is the use of electrochemical sensors, known for their rapid and accurate detection capabilities as well as their fast and cost-effective procedures [2]. Selecting the appropriate material is crucial for constructing this type of sensor. MXenes, due to their exceptional electrical and other properties [3,4], can potentially be employed for the electrochemical detection of cadmium. In this study, we demonstrate the characteristics and dependencies of an MXene-Nafion/GCE electrochemical sensor for cadmium detection. The sensing performance is influenced by the pH and temperature of an acetic buffer solution, achieving higher sensitivity in warmer, more acidic environments. At a pH of 4.5, the sensor exhibits a linear range from 1.03 to 27.53 µM, with a detection limit of 0.82 µM and a sensitivity of 5.11 µA/(µM·cm²). The proposed sensing mechanism is linked to the interaction between cadmium ions and the hydroxyl surface termination groups. A high concentration of MXenes on the electrode surface impedes sensing, indicating a potential stacking issue. The sensor was successfully tested in lake and river water to simulate real-world conditions. Our findings suggest that the sensor could serve as a promising candidate for fast, accurate, and selective monitoring of cadmium levels near industrial sites.