Controlled pore structure and surface properties of petroleum pitch-based mesoporous carbon prepared using silica as a template

Petroleum pitch-based mesoporous carbons were synthesized using a colloidal silica templating method, and the effects of imprinting temperature, pitch-to-silica ratio, and H₂O₂ oxidative pretreatment on pore development and surface chemistry were systematically investigated. The imprinting process facilitated the infiltration and dispersion of silica particles within the softened pitch matrix, leading to the formation of interconnected mesoporous structures after carbonization and silica removal. The mesoporous carbons exhibited typical type-IV N₂ adsorption–desorption isotherms with H2-type hysteresis loops, indicating the presence of interconnected mesopores. Among the investigated conditions, the sample prepared at an imprinting temperature of 350 °C with a pitch-to-silica ratio of 1:2.4 showed the most developed mesoporous structure, exhibiting a specific surface area of 342 m² g⁻¹ and a total pore volume of 1.11 cm³ g⁻¹. H₂O₂ oxidative pretreatment introduced oxygen-containing functional groups onto the pitch surface, improving the interaction between pitch and hydrophilic silica particles. Moderate oxidation for 2 h further enhanced the specific surface area to 446 m² g⁻¹ and increased pore accessibility while maintaining structural stability. However, excessive oxidation caused structural degradation and reduced pore uniformity. XRD analysis revealed that all samples possessed low graphitic ordering characteristic of template-assisted mesoporous carbons, while XPS and FTIR analyses confirmed the introduction and partial retention of oxygen-containing functional groups after carbonization. The resulting mesoporous carbons exhibited high mesopore fractions exceeding 90% and pore sizes in the range of 15–25 nm, suggesting their structural suitability as catalyst supports for proton exchange membrane fuel cells (PEMFCs).