Fig. 4 shows scanning electron micrographs of the porous carbon fibers. A photograph of the cross-section of a fiber ∼100 μm in diameter can be seen in Fig. 4a. The pore diameter ranged from submicrometers to ∼2 μm as seen in the enlarged cross-section in Fig. 4b. Fig. 4c shows that elongated thin pores were well aligned parallel to the fiber axis. This appears to be a unique porous structure.