Hydrogen Oxidation and Oxygen Reduction Reactions on an OsRu-Based Electrocatalyst Synthesized by Microwave Irradiation.

Ángela Selva-Ochoa,Lorena Magallón-Cacho,Edgar Borja-Arco,Javier Su-Gallegos,Pathiyammattom Joseph Sebastian

doi:10.3390/ma14195692

Abstract

This work presents an OsRu-based electrocatalyst synthesis, by a rapid and efficient method through microwave irradiation. The outstanding electrocatalyst shows a dual catalytic activity, demonstrating both: hydrogen oxidation and oxygen reduction reactions. The material is structural and morphologically characterized by FT-IR, X-ray diffraction, EDS, and SEM, indicating nanoparticulated Os and Ru metallic phases with a crystallite size of ∼6 nm, calculated by the Scherrer equation. The metal nanoparticles are apparently deposited on a carbonaceous sponge-like morphology structure. Its electrochemical characterization is performed in 0.5 M H2SO4 by the rotating disk electrode technique, employing cyclic and linear sweep voltammetry. Two different ink treatments have been studied to improve the obtained polarization curves. The material is also tested in the presence of methanol for the oxygen reduction reaction, showing an important resistance to this contaminant, making it viable for its use in direct methanol fuel cells (DMFCs) as a cathode and in polymer electrolyte fuel cells (PEMFCs) as an anode as much as a cathode.

Highlights

The results show that the OsRu electrocatalyst has a higher Ru amount than Os
The difference between the expected and experimental molar ratio could be a consequence of the Ru3 (CO)12 solubility in dichlorobenzene, which is greater than the Os3 (CO)12 one
A bimetallic OsRu-based electrocatalyst was synthesized by microwave irradiation, resulting in a nanometric glomerular structure able to perform the hydrogen oxidation reaction (HOR) and/or the oxygen reduction reaction (ORR), showing an improved catalytic activity towards these reactions in comparison to its bimetallic homologue reported in the literature

Summary

Introduction

A PEMFC is an efficient and environmentally friendly power device that converts chemical energy into electrical energy through two electrochemical reactions: the hydrogen oxidation reaction (HOR) at the anode and the oxygen reduction reaction (ORR) at the cathode. Both electrochemical reactions are usually promoted by electrocatalyst materials composed of metal nanoparticles supported on carbon, whose activity becomes crucial for cell operation. Whereas for the ORR, the sluggish kinetics lead to high overpotentials, giving as result exchange current densities three to four orders of magnitude lower compared to the anodic reaction (j0 ≈ 10−3 –10−4 mA cm−2 ) [2,3]. The synthesis of new electrocatalysts with dual activity as both anode and cathode in a PEMFC, to decrease

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Conclusion