Structural Evolution of Activated Carbon Fiber during Physical Activation

Abstract

PAN-based precursor fibers were subjected to chemical-free physical activation after undergoing a continuous stabilization process. The manufactured activated carbon fibers were analyzed for structural changes based on activation temperature through surface area, pore size distribution, and Raman spectroscopy. With an increase in activation temperature, a phenomenon of pore opening, and the formation of smaller pores were observed, alongside a rising trend in surface area. Notably, at 950 ℃, the highest values for surface area and pore volume were observed. Additionally, the pore size distribution indicated that over 50 % of the pores were micropores with a size of 2 nm or smaller. Furthermore, the ID/IG ratio was at its lowest, confirming the well-developed graphitic structure at the atomic scale at this temperature. However, beyond an activation temperature of 950 ℃, a sharp decrease in both surface area and the proportion of micropores was observed. The ID/IG also exhibited a significant increase, indicating an excessive level of physical activation, resulting in structural deterioration beyond a certain temperature threshold.