Synthesis of graphitic carbon nitride-enhanced manganese oxide microspheres for ultra-sensitive electrochemical detection of mercury (II) in environmental water sample

Abstract

Mercury (Hg2+) is a highly toxic heavy metal in environmental water samples, resulting from improper releases, and causing widespread contamination with significant impacts on human health. Developing an appropriate method for detecting the toxic metal Hg2+ is crucial. Despite manganese oxide (MnO2) being employed for Hg2+ detection, its suboptimal electrocatalytic performance, due to inadequate electrical conductivity, stability, and chemical reactivity, prompted our innovative approach. We addressed this issue by utilizing a nitrogen-rich carbon source, 2D graphitic carbon nitride (g-C3N4), in conjunction with MnO2, crafting the MnO2@g-C3N4 composite to boost Hg2+ capabilities. A thorough analysis of the MnO2@g-C3N4 composite explored its structural, physical, and chemical properties, while different electrochemical techniques were employed to evaluate its electrocatalytic behavior. Consequently, MnO2@g-C3N4 composite-modified screen-printed carbon electrode (MnO2@g-C3N4@SPCE) demonstrated notable characteristics, including a detection limit (2.6 nM), an extended linear range, superior selectivity, and repeatability in Hg2+ detection. Moreover, the MnO2@g-C3N4 sensor, with a high recovery rate for Hg2+ in real sample analysis, particularly river water, showcased its excellent practicality attributed, to the synergistic effect between MnO2 and g-C3N4, providing numerous electroactive sites.