<i>In situ</i> polypyrrole coating on copper foam <i>via</i> femtosecond laser-irradiation for supercapacitor applications

The growing need for fast, efficient, and durable energy storage, especially in electric vehicles and renewable energy systems, has made supercapacitors (SCs) increasingly important. Their ability to charge rapidly, deliver high power, and withstand thousands of cycles makes them a strong alternative to traditional batteries. In this study, we present a simple and effective method for the <i>in situ</i> polymerization of polymerize polypyrrole (PPy) on copper (Cu) foam using femtosecond (Fs) laser pulses. This single-step process enables direct polymerization of the pyrrole monomer on the Cu foam surface, creating a uniform, binder-free and strongly adhered PPy layer. Electrochemical testing reveals that the fabricated electrode (Femto-Cu PPy) exhibits significantly enhanced capacitance (148.5 mF cm^-2 at 0.5 mA cm^-2), stable performance at various current densities, and retains approximately 78.6% of its capacity after 10 000 charge-discharge cycles. Furthermore, well-established models such as Lindström's, Trasatti's, and Dunn's methods were employed to analyze and quantify the charge storage mechanism. Overall, this approach offers a practical and scalable method for producing high-performance SC electrodes by integrating laser processing with conductive polymer chemistry.