Si–CN for the oxygen reduction reaction in alkaline media, the effect of synthesis temperature

Abstract

The electrocatalytic properties of silicon-doped carbon nanotubes (Si–CN) for oxygen reduction reaction (ORR) in alkaline media are reported. The Si-CNs were obtained by a modified chemical vapor deposition method. The Si–CN showed good activity towards ORR since most of the process was carried out efficiently by the four-electron transfer pathway, and it exhibited a low Tafel slope of 84.28 mV dec−1 indicating that the material has a good kinetic activation response for ORR. This favorable response was attributed to 0.29 at. % silicon intercalated in the carbon lattice enhancing electrons transport at neighboring silicon sites. In addition, its mechanical robustness and thermodynamic stability influenced by the synthesis temperature contributed favorably to the energetic activation of Si–CN to the adsorption and reduction of oxygen. Therefore, Si–CN could be considered a potential metal-free and low-cost material for the ORR in alkaline fuel cells.