Tuning porosity and capacitance of laser-assisted grown graphene by controlled thermal annealing

• • Mild annealing in air at 400 °C for 6 h increases specific surface area from 110 to 498 m² g⁻¹ (4.5-fold), directly enhancing ion-accessible sites and nearly order-of-magnitude capacitance increase, critical for high-energy-density supercapacitors. • • Optimal electrodes retain 92% capacitance at a 25-fold current increase (5 mA cm⁻²), demonstrating superior rate capability essential for power delivery applications. • • Long-term cycling stability: 99% capacitance retention after 10,000 cycles, ensuring device longevity and reducing replacement costs in industrial applications. • • Annealing promotes deoxygenation and higher sp2/sp3 ratio, improving electrical conductivity and electrochemical activity, as confirmed by spectroscopy, enabling more efficient charge transfer.