MoS2@MWCNT modified glassy carbon electrode for electrochemical mercury(ii) ion sensors

Abstract

Mercury (Hg²⁺) sensors play a crucial role in monitoring the quality of drinking water and ensuring that the concentration of Hg²⁺ ions remains within the permissible limits set by the World Health Organization (WHO). This study introduces a carefully fabricated electrochemical sensor that can accurately detect Hg²⁺, with high selectivity and sensitivity. The sensor utilizes cyclic voltammetry (CV) to accurately measure Hg²⁺ concentrations. An advanced composite electrode is fabricated by combining multi-walled carbon nanotubes (MWCNT) and MoS₂ on a glassy carbon electrode (GCE) substrate, which functions as the sensing element. The interaction between MWCNT and MoS₂ enhances electron transfer kinetics at the electrode interface, leading to faster reactions. These results show a significant 32-times increase in the peak current response for Hg²⁺ reduction compared to the bare GCE. As a result, the sensor can achieve a low detection limit (LoD) of 2 nM, surpassing the strict safety standards set by the WHO for Hg²⁺ in water. In addition, the fabricated electrode shows exceptional selectivity towards Hg²⁺. There are very few changes in the current when different heavy metal ions, such as Pb²⁺, Co²⁺, and As³⁺, are present. In addition, the sensor demonstrates exceptional repeatability, reproducibility and stability, showcasing its great promise for real-world use in monitoring the environment and conducting advanced chemical analysis.