Rapid fabrication of hierarchical carbon nanofiber electrodes via nanosecond laser processing for electrochemical bilirubin detection

Carbon nanofiber (CNF)-based electrodes have garnered significant interest over the past couple of years due to their excellent physicochemical and electrochemical properties. However, traditional fabrication typically requires high-temperature treatments and complex, multi-step procedures. There remains a need for a rapid, industrially scalable, and cost-effective process for CNF-based electrode fabrication. Here, we report a facile and rapid approach to prepare binder-free, highly interconnected CNF electrodes by exposing simple electrospun cuvette-like polyacrylonitrile (PAN) nanofiber (NF) mats to nanosecond laser treatment. The effects of laser power (0.3, 0.9, 1.5, 2.25, and 3.0 W) on carbonization and the structural transformation of NFs, were thoroughly characterized. The results showed that the morphological, electronic, and electrocatalytic behaviors of the CNF electrodes were strongly dependent on the applied laser power. Electrochemical test results showed that the CNF electrodes exhibited excellent electrocatalytic properties for the enzyme-free detection of bilirubin (BR). They showed high sensitivity (0.2419 μA μM⁻¹), a wide linear range (10-275 μM), a low detection limit (1.2 μM; 3σ/S), and good selectivity and reproducibility. This work presents a versatile strategy for scaling up the rapid fabrication of advanced carbon-based electrochemical sensors.