High‐performance Mg²⁺ Sensors Based on Natural Rubber‐derived, Label‐free Carbon Dots

Abstract

Detection of trace magnesium ion (Mg 2 + ) is important in environmental and health monitoring. In this work, highperformance Mg 2 + sensor was developed from label-free carbon dots. The novel carbon dots were prepared for the first time from natural rubber through the two-step pyrolysis and hydrothermal method. They showed selectivity towards Mg 2 + against a range of metal ions in solution and yielded a detection limit of 4.3 μM. The Mg 2 + detection in real water samples showed an excellent recovery of 97.21 to 99.21 %. A paper-based sensor was also fabricated as a portable device, showing a detection limit of 8.0 μM. UV-vis and X-ray absorption studies provided some evidences of the unique dynamic interactions between carbon dots and Mg 2 + ions. In summary, the novelty of this work lies upon (i) developing a methodology of converting abundant, low-cost natural rubber into carbon dots and (ii) fabricating sensitive and selective sensors from the label-free carbon dots for the detection of Mg 2 + both in solution and as paper-based devices. The findings in this work will therefore have potential for environmental and health monitoring applications.