Ismail Abidat
University of Poitiers, France
Title: Highly Active and Stable Heteroatoms-Doped Supported Spinel Nanoparticles as Bi-functional Oxygen Electrocatalysts
Biography
Biography: Ismail Abidat
Abstract
Rechargeable alkali Metal-air batteries are one of the most promising energy storage systems due to its extremely high theoretical energy density. However, its development requires the design of effective and robust bi-functional electrocatalysts that act as air electrode for oxygen evolution (OER) and oxygen reduction (ORR) reactions. Especially, reduction of overpotentials, promotion of reaction kinetics and long term reliability under repeated OER and ORR cycles are some of the main features of an optimal high-performance electrocatalyst. In this context, composite electrode materials have been recently synthesized by coupling heteroatom-doped graphene like materials with spinel-type transition metal oxides. This combination leads to the formation of oxide-carbon heterointerfaces able to enhance the electrocatalytic activity of materials towards OER and ORR as well as their stability. Therefore, in the present work, we have synthesized nanocomposite catalysts made of Co3O4 nanoparticles deposited onto various nitrogen-doped as well as onto nitrogen and sulfur dual-doped graphene oxide materials as non-noble bifunctional electrocatalyst using an original microwave heating method. The heteroatoms-doped graphene materials were prepared using hydrothermal and thermal methods in order to control ratio and nature of Nitrogen functionalities. The crystallinity of the nanocomposites was confirmed by X-ray diffraction (XRD). Transmission electron microscopy (TEM) allowed investigating morphological characteristics. Rotating Ring disk (RRDE) measurements revealed that the value of the reversibility criterion could be tuned depending on the chemical nature of the heteroatom-doped graphene-like material and on the morphostructural properties of the different catalysts. We also investigated the stability of the Co3O4/N,S-RGO in harsh conditions of repeated OER and OER cycles. In 6 M KOH at 10 mA cm-2 (12 h per cycle) in OER and 8 mA cm-2 (8 h per cycle) in ORR, no loss in activity was detected after 200 h (Figure 1). The obtained results show that the synthesized nanocomposites are promising air electrode candidates for metal-air batteries.
