Nanostructured graphitic carbons have widespread applications. However, the synthesis of such materials with a high surface area is still a great challenge. In this study, we demonstrate a new approach for improving the surface area. Graphitic carbon nanocages (CNCs) are prepared by spray pyrolysis of ethanol with dissolved iron carbonyl at high temperature. Ammonium thiocyanate is added to form iron sulfide as a less active catalyst and a template with less carbon dissolution and precipitation than single-phase Fe. This addition leads to an apparent reduction in cage size from 60 to 40 nm and wall thickness from 5–10 nm to 2–4 nm and a significant increase in surface area from 227 to 550 m2 g−1 at 800 °C. As an example of a potential application, the CNCs with a thin wall and high surface area are demonstrated to be a superb material for supporting the Pt catalyst used in low-temperature fuel cells. It is suggested that the present approach may be integrated with previous methods for improving the surface area of graphitic carbons and their performance in many areas of interest.