Methodological guidance to the batch preparation of graphene-based sensor for low-cost and high-performance Cd and Pb detection.

The cost-effective, disposable, batch-prepared electrochemical sensors with high sensitivity and accurate detection are essential to the rapid on-site detection of heavy metals in soil and water. Here, we report a one-step laser additive manufacturing technique for the batch fabrication of electrochemical sensors. With the systematic optimization of multiple laser parameters (including laser power, engraving speed, and frequency), highly sensitive laser-induced porous graphene (LIPG) electrodes were fabricated to detect Cd and Pb efficiently. Followingly, with the modification of Nafion and bismuth-film, the obtained Bi/Nafion/LIPG electrode showed excellent repeatability, stability, selectivity, and outstanding detection limits of 0.25 µg/L for Cd and 0.41 µg/L for Pb, respectively. As-prepared Bi/Nafion/LIPG electrode also works in actual soil and water samples, with an average recovery of 99.61 and 99.90 for Cd and Pb. Furthermore, from the perspective of the laser photothermal effect, the important influence of laser parameters on the physical and chemical properties of LIPG was analyzed, confirming that the laser photothermal effect has a superimposed cumulative effect on the surface of the PI film. This study provides a new methodical guidance for the rapid and batch preparation of LIPG electrodes with the advantages of low-cost, disposable, high-sensitivity, and flexibility, which can promote the on-site electrochemical detection of heavy metals in soil and water.