3.2. Preparation of N-Doped Porous Carbon

The tobacco straw powder, melamine, and solid K₂CO₃ were added proportionally to the mortar (1:x:2) and then sufficiently ground to form a homogeneous mixture. After that, the mixture was transferred to a corundum container with a lid, heated at 800 °C for 100 min in a tube at a ramp rate of 10 °C/min under argon protection, and then naturally cooled. The collected sample was added to a beaker with 1 M HCl and stirred for 30 min to remove the excess activator and other by-products, such as inorganic salts. Finally, the filtered product was washed thoroughly with distilled water and dried at 120 °C for 12 h. The prepared product was noted as N-YACx, where x denotes the mass ratio of tobacco straw powder to melamine (x = 0.5, 2, 2). In addition, as a comparison, the product prepared without the addition of melamine was named YAC.