Optimizing laser-induced graphene oxide electrodes for electroanalytical applications using response surface methodology

Laser-induced graphene (LIG) electrodes have shown promise for electroanalytical applications because of their unique properties, precise thickness, and morphology control. This study optimized the fabrication parameters of LIG electrodes on the thinnest commercial polyimide tapes by employing response surface methodology (RSM) combined with a randomized Box-Behnken experimental design (BBD). Kapton polyimide (PI) tapes were laser-engraved to create a three-electrode electrochemical system. Laser power, engraving speed, and laser distance were evaluated using the heterogeneous kinetic constant (k°) as the response variable. Optimal conditions were identified as 1.925 W power, 2729 mm/min speed, and 7.6 mm focal distance, yielding peak differences of 93 mV, electric double-layer capacitance of 1.95 µF, anodic peak current of 60.1 µA, and k° of 0.0074 cm/s. Raman spectroscopy of the LIG showed peaks at ~ 1350 cm⁻¹ (D band), ~ 1580 cm⁻¹ (G band), and ~ 2700 cm⁻¹ (2D band), indicating disordered and ordered graphitic structures. XRD analysis confirmed the presence of amorphous adhesive material and partial restoration of the graphene structure, with peaks corresponding to reduced graphene oxide (rGO) and graphitic planes. Reproducibility and repeatability studies via cyclic voltammetry (CV) in Fe(CN)₆³⁻/⁴⁻ solution showed minor variations in peak currents and potentials, with RSD values of 2.64% for anodic and 2.26% for cathodic currents. Stability over 120 cycles showed an RSD of 1.57% for potentials and 3.53% for currents, with long-term tests over 20 days revealing a 14.5% and 15.9% decrease in anodic and cathodic peak currents, respectively. Optimized LIG electrodes were used to determine catechol (CC) and ascorbic acid (AA) using differential pulse voltammetry (DPV). CC determination yielded a linear range of 2 to 400 µM with a limit of detection (LOD) of 0.37 µM and a limit of quantification (LOQ) of 1.25 µM. AA determination resulted in a linear range of 20–4000 µM with an LOD of 4.26 µM and an LOQ of 14.21 µM. These results highlight the excellent performance of the optimized LIG electrodes in electroanalytical applications.