Laser-Assisted In Situ Fabrication of rGO/Bi₂O₃ Nanocomposites for Heavy Metal Sensing

In this work, we introduce a laser-assisted approach to synthesize reduced graphene oxide/bismuth oxide (III) (rGO/Bi₂O₃) nanocomposites through a single-step CO₂ laser photothermal process. While rGO/Bi₂O₃ composites have been previously reported, to the best of our knowledge, this work represents the first demonstration of their formation via a single-step CO₂ laser-assisted photothermal process, enabling direct integration into flexible electrodes. This method simultaneously reduces graphene oxide to conductive rGO and decomposes bismuth nitrate into Bi₂O₃ nanoplatelets, which self-assemble homogeneously within the carbon matrix. The resulting hybrid exhibits an interconnected architecture that promotes electron transport and provides abundant active sites for metal ion adsorption and redox activity. Morphological and spectroscopic analyses confirm the uniform integration of Bi₂O₃ within the rGO network, while electrochemical measurements reveal excellent stripping voltammetric performance toward Pb(II), Cd(II), and Cu(II), characterized by linear responses with high correlation coefficients and estimated detection limits of 5.3 ppb for Pb(II), 11.6 ppb for Cd(II), and 1.6 ppb for Cu(II). Beyond its analytical sensitivity, the simplicity and reproducibility of this fabrication strategy demonstrate a path toward large-scale, low-cost, and environmentally friendly sensor production. This work establishes laser-engineered rGO/Bi₂O₃ electrodes as promising platforms for on-site water quality monitoring and next-generation portable electrochemical devices.