Fabrication of hierarchical micro/nano structure using UV laser for application in PANI electrodes of supercapacitors

This study employed an ultraviolet (UV) laser to create structures with micro- and nanoscale features. Initially, microstructures were fabricated by combining UV laser irradiation with 3D μ-printing technology utilizing monomer polymerization and crosslinking chemical reactions. Subsequently, UV laser interference lithography is applied to expose a positive photoresist on top of the microstructures, inducing a photochemical reaction that, after development, forms nanopatterns. These micro/nano hierarchical structures can then be replicated using PDMS (polydimethylsiloxane) molding to produce inverse molds for the structures. Finally, a solution of chemically oxidative polymerized polyaniline (PANI) is coated onto the PDMS mold. After baking and demolding, a PANI film with micro/nano hierarchical structures was obtained and used as the working electrode in supercapacitors. Compared to planar-coated PANI films, hierarchical structures increase the electrode surface area, contributing to an enhanced specific capacitance. To understand its electrochemical properties, cyclic voltammetry (CV) and galvanostatic charge–discharge measurements were performed. Compared to the non-structured PANI, the specific capacitance of the microstructured PANI and the micro/nano hierarchical structured PANI increased by approximately 30 % and 60 %, respectively.