Comparing Structure and Sorption Characteristics of Laser-Induced Graphene (LIG) from Various Polymeric Substrates

Laser-induced graphene (LIG) has recently gained significant attention for its potential application in various fields. Here, we show that the laser ablation of Kevlar fabric, polyimide (PI), and poly(ether)sulfone (PES) substrates results in the formation of a highly porous graphene with different physicochemical features. LIG powder was used as an adsorbent for the dye removal. The LIG materials obtained from each substrate exhibited a different macroporous structure and demonstrated relatively high efficiency in the adsorptive removal of cationic dye. The generation of graphene from each polymeric substrate was confirmed by characterizing the LIGs. We found that the laser power had a large influence on the formation and quality of the LIG; higher laser power increased the degree of graphitization and resulted in a more porous graphene structure, which eventually led to an increase in the adsorption capacity. The LIG's adsorption capability is hypothesized to be primarily due to the highly porous structure of LIG, while π–π and hydrophobic interactions were found to have a marginal influence on the adsorbent–adsorbate interactions. LIG derived from PI displayed the highest sorption capacity among different polymeric substrates tested. The maximum equilibrium methylene blue adsorption capacity was found to be 153.3 mg/g using the Langmuir model.