Aqueous-based synthesis of ruthenium–selenium catalyst for oxygen reduction reaction

Abstract

Carbon-supported Se/Ru(Se) catalysts of a broad range of composition were synthesized via a reduction procedure in which a mixture of RuCl₃, SeO₂ and Black Pearl carbon was treated with NaBH₄ in basic media at room temperature. Physical characterization of the catalyst was performed by X-ray diffraction, energy dispersive X-ray spectroscopy and by high resolution transmission electron microscopy. The effect of NaOH addition during the reduction by NaBH₄ and the impact of a post-reduction thermal treatment at 500 °C were interrogated. The activity of the catalyst towards the oxygen reduction reaction was studied by the use of a rotating disk electrode. It was found that the half-wave potential for the oxygen reduction reaction was about 0.78 V vs. RHE. The Se-to-Ru ratio and metal loading on carbon were optimized for the oxygen reduction reaction and the optimized catalyst was tested at the cathode of a polymer electrolyte fuel cell. The stability of the Se/Ru(Se) catalyst was evaluated by electrochemical cycling and by leaching the catalyst in 0.5 M H₂SO₄ at 80 °C.