Electrocatalytic oxygen reduction reaction activity of KOH etched carbon films as metal-free cathodic catalysts for fuel cells

In this article, surface-modified graphite materials as cathodic catalysts are prepared by hot filament chemical vapor deposition and then chemically etched by KOH solution. Surface morphology, elemental composition, microstructure and surface chemical state of the modified graphite films are characterized by scanning electron microscopy, transmission electron microscopy, energy dispersive spectroscopy, Raman spectroscopy and X-ray photoelectron spectroscopy techniques. Results indicate that the surface of the pristine graphite can be refined to effectively improve the surface area by etching using the KOH solution with a moderate concentration. The graphite catalyst etched with 4.8 mg mL(-1) KOH solution shows a higher catalytic activity for the oxygen reduction reaction and a superior methanol tolerance than that of the un-etched and the other etched graphite catalysts. The stability of the etched graphite materials needs to be improved.