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 degrees 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 degrees C.

Se-modified Ru nanoparticles as ORR catalysts – Part 1: Synthesis and analysis by RRDE and in PEFCs

“…The performance of the catalysts observed in the polarization plots also followed this ranking, with the Se/Ru(aq) catalyst showing the highest performance. To the best of our knowledge, these performances are higher than those described for Se/Ru-type catalysts in previous reports [30,31,37]. The Ru black catalyst performed better overall than would have been expected based on the RRDE experiments, and even showed slightly better performance than the Se/Ru catalysts at voltages higher than 0.55 V. The Ru black may benefit from H 2 crossover from the anode during the fuel cell test, or the lower water activity in the fuel cell compared to the aqueous electrolyte, which would contribute to a more reduced state of the catalyst.…”

“…The former comparison to Ru is important for fundamental understanding, and the latter comparison to Pt is necessary to define the conditions of technological relevance for Ru-based catalysts. The performances of MEAs prepared with this new Se/Ru catalyst in H 2 -air fuel cell tests [30,31,37] and DMFC tests [30,31,35] are also higher than those described in previous reports.…”

Carbon‐Supported, Selenium‐Modified Ruthenium–Molybdenum Catalysts for Oxygen Reduction in Acidic Media

“…[19] Details of the synthesis procedures have been reported elsewhere; [31] herein, the key steps are briefly described. …”

“…[19,31] The catalysts produced in this manner showed high ORR activities compared to other Ru-based chalcogenide catalysts. Furthermore, we found that incorporating small amounts of elemental Mo into these catalysts considerably increased their stability.…”

Positive Effect of Heat Treatment on Carbon-Supported CoS Nanocatalysts for Oxygen Reduction Reaction

“…The half-wave potential is also enhanced from 0.64 V for the as-prepared sample to 0.71 V for CoS-400, and then reduced to 0.51 V for CoS-450. The value of 0.71 V is the highest value among non-precious metal chalcogenides [3,11] and very close to 0.77 V for RuSex/C [20]. At 2500 rpm, in comparison, jR (HO2 − oxidation) is much smaller than jD (oxygen reduction), meaning that H2O was the main product of ORR catalyzed by the prepared catalysts.…”