Figure 3

SEM images of heat-treated electrospun fibers under different conditions. (A) 550°C, N₂; (B) 550°C, NH₃; (C) 600°C, N₂; (D) 600°C, NH₃; (E) 650°C, N₂; and (F) 650°C, NH₃. The EDS of heat-treated fibers at 550°C in NH₃(G) show the composite fibers without calcination.