Figure 4

SEM images, XRD patterns, and thermogravimetric analysis. SEM images of the graphitic hollow carbon sphere (a) before and (b) after sulfur impregnation. (c) The XRD patterns of the mixture of the graphitic hollow carbon and sulfur before and after the heat treatment at 155°C in vacuum, and (d) the TGA recorded for the sulfur-impregnated graphitic hollow carbon in N₂ atmosphere at a heating rate of 10°C/min.