Influence of Pre-oxidization on the Surface Condition, Pore Structure and Capacitance Performance of Activated Carbon Derived from Coal Gasification Fine Slag

The re-utilization of Coal Gasification Fine Slag (CGFS) is essential for sustainable waste management, reducing pollution and optimizing resource utilization. Converting CGFS into high-value Activated Carbon (CGFS-AC) is a key strategy for utilizing Coal Gasification Slag (CGS). Due to the dense carbon structure formed at high gasification temperatures, activation is challenging. The pre-oxidation process can introduce oxygen-containing groups on the residual carbon surface, which is an effective approach to change the surface condition and to promote the pore development of Activated Carbon (AC). The experimental results show that the specific surface area and pore volume of oxidized activated carbon increase significantly. The O–C=O groups enhancing pore formation, while C=O groups may inhibit it. The oxygen-containing groups modify surface polarity and acidity, facilitating KOH activation. The ACs prepared by De-ashing Carbon-Rich Particle (D-CRP) after pre-oxidation show a unique pore structure that promoting charge transfer in charge-discharge process. The 15   wt% HNO 3 pre-oxidized sample (15% NA-CRP-AC) achieves a high specific capacitance of 403.2   F/g at 0.5   A/g, excellent rate capability, and outstanding cycle stability, making it a promising supercapacitor electrode material.