Laser-induced carbonization of cellulose acetate for controlled carbon structure evolution

Biomass offers a low-cost and sustainable carbon source. Yet, conventional pyrolytic routes remain energy intensive and require harsh processing conditions. Laser-induced carbonization provides a rapid, efficient and green alternative for the conversion of biomass into carbon structures. Building on the growing demand for sustainable alternatives to petroleum-derived polymers in laser writing, we investigate laser-induced carbon (LIC) produced from cellulose acetate (CA) membranes, a widely available biopolymer, via CO₂ laser irradiation. The flame-retardant bis[2-(methacryloyloxy)ethyl] phosphate (BMEP) enables localized carbonization, overcoming CA's poor thermal stability. By tuning laser parameters, namely the defocus distance and the number of passes, we selectively obtain amorphous carbon, activated carbon (AC), graphene oxide (GO), and laser-induced graphene (LIG). Among these, AC fabricated through a double-pass process at a defocus distance of 7.5 mm achieves outstanding electrochemical performance as a microsupercapacitor (μSC) electrode, delivering an areal capacitance of up to 63 mF cm^-2, an energy density of 3.3 µWh cm^-2, and a power density of 0.42 mW cm^-2. These results outperform those of petroleum-based polymer-derived LIG while utilizing a potentially upcycled precursor. This work expands the scope of LIG precursors and offers a versatile platform for engineering sustainable carbon-based electrodes.