Simple laser-induced graphene fiber electrode fabrication for high-performance heavy-metal sensing

In this paper, we describe the simple fabrication and characterization of a high-performing heavy metal sensor by using laser-induced graphene fiber (LIGF) electrodes for simultaneous detection of cadmium (Cd²⁺) and lead (Pb²⁺) ions. Both LIG and LIGF were grown via extremely simple and fast method, compared to conventional graphene synthesis, on a commercial polyimide film by irradiating CO₂ infrared laser with the appropriate energy level (46 J/cm² in this work). Fabricated LIG and LIGF were analyzed by FE-SEM and Raman spectroscopy, which showed that the LIGF structure was composed of randomly stacked three-dimensional porous graphene layers and fibers. On the surface of the LIGF working electrode, bismuth was electro-deposited in-situ for the electrochemical detection of heavy metal ions. The fabricated LIGF electrode heavy metal sensor was used for the simultaneous detection of Cd and Pb ions in 0.1 M acetate buffer solution at pH 4.5 by square wave anodic stripping voltammetry. The fabricated LIGF-based heavy-metal sensor showed high sensitivity (0.19 and 0.20 μA μg⁻¹ L for Cd and Pb ions), broad linear detection ranges (1.0 to 140.0 μg/L for Cd and Pb ions), and low detection limits (0.4 μg/L (S/N = 3) for both Cd and Pb ions), showing great promise in high-performance heavy metal detection applications that require fast and simple manufacturing practices.