Heterogeneous atoms-doped titanium carbide as a precious metal-free electrocatalyst for oxygen reduction reaction

Abstract

Developing precious metal-free electrocatalysts with both high and stable oxygen reduction reaction (ORR) electrochemical activity is still the key challenge in the wide application of clean energy, e.g. fuel cells or metal air batteries. Here, TiC based precious metal-free ORR catalyst has been studied by doping heterogeneous atoms. N-doping results in enhanced ORR performance of N/TiC, which was further elevated by introducing metal (e.g. Fe, Co) into TiC powders. Especially, the resultant Fe-N/TiC demonstrates the highest ORR activity among the prepared samples, which exhibits approximate 4e− pathway with a comparable electron-transfer number to the benchmark 20 wt%Pt/C, and much higher methanol tolerance than the latter in alkaline media. The high ORR performance of Fe-N/TiC composite could be ascribed to the cooperative effects of both N and metal doping, in which the N doping would lead to the change of electronic structure near the TiC surface and the formation of C-N active sites, and the metal species addition leads to the formation of a certain amount of Me-Nx active sites resulting in the further ORR activity enhancement. The reasonably high and stable electrochemical catalytic activity and the excellent methanol tolerance make the precious-metal free Fe-N/TiC composite a promising candidate cathode catalyst in ORR.