Efficient Metal-Free Oxygen Reduction in Alkaline Medium on High-Surface-Area Mesoporous Nitrogen-Doped Carbons Made from Ionic Liquids and Nucleobases

Abstract

Mesoporous nitrogen-doped carbon materials with high surface areas up to 1500 m² g⁻¹ were conveniently made by the carbonization of nucleobases dissolved in an all-organic ionic liquid (1-ethyl-3-methylimidazolium dicyanamide). Using hard templating with silica nanoparticles, this process yields high-surface-area nitrogen-doped carbon materials with nitrogen contents as high as 12 wt %, narrow mesopore size distribution of ca. 12 nm diameter, and local graphitic carbon structure. It is demonstrated that the resulting nitrogen-doped carbons show very high catalytic activity, even in the metal-free case in the oxygen reduction reaction (ORR) for fuel cells. Specifically, the as-prepared materials exhibit a low onset voltage for ORR in alkaline medium and a high methanol tolerance, compared with those of commercial 20 wt % Pt/C catalyst. We regard this as a first step toward an all-sustainable fuel cell, avoiding noble metals.