Femtosecond laser-driven synthesis of laser-induced graphene: Optimizing microstructure and electrochemical...

Laser-induced graphene (LIG) offers significant potential for advanced technological developments. This study utilized a femtosecond laser (1030 nm, 500 kHz, 400 fs) to irradiate polyimide in air, producing LIG electrodes. The impact of laser parameters (power, scanning speed, defocus distance, hatch spacing) on LIG's microstructure and electrochemical performance was systematically investigated, revealing that optimized energy density enhances graphitization, minimizes defects, and tailors surface chemistry and porosity, thereby enhancing electrochemical performance. Under optimized conditions (3 W, 10 mm/s, 0.0 mm, 25 μm), LIG exhibited high quality, confirmed by complementary techniques. Raman spectroscopy indicated high graphitization with a low I_D/I_G ratio, signifying minimal defects. X-ray Photoelectron Spectroscopy revealed 85.67 % carbon content and 7.89 % oxygen groups. Scanning Electron Microscopy showed a uniform three-dimensional porous structure. Electrochemical tests, including cyclic voltammetry and impedance spectroscopy, demonstrated excellent performance with a sheet resistance of 9.49 Ω/sq., a charge transfer resistance of 123.16 Ω, and an active surface area of 1.206 cm². Compared to CO₂ or nanosecond lasers, femtosecond laser processing offers submicron precision and reduced thermal damage, simplifying fabrication and enhancing LIG's customizability. These findings provide theoretical guidance for precise LIG synthesis, supporting its applications in advanced sensors and supercapacitors.