Title : Polyoxometalates as electrocatalysts for rechargeable metal air batteries
Abstract:
Metal-air batteries (MABs) are promising electrochemical energy conversion and storage devices due to having high energy density, while being safer than most batteries. They are composed of a pure metal anode and use air in the cathode, making them significantly lighter and cheaper than other models. By using bifunctional electrocatalysts, MABs can be rechargeable. In that case, atmospheric O2 is reduced in the cathode during discharge by the well-known oxygen reduction reaction (ORR), while the metal is oxidized to its ionic form. During the charge, the ions are reduced back to their metallic form, and the oxygen evolution reaction (OER) takes place at the positive electrode. Thus, efficient and lower-cost bifunctional electrocatalysts are required for the oxygen electrode to ensure good performance and commercial availability of MABs. Polyoxometalates (POMs), due to their unique structure and properties, have recently shown promise for energy storage and conversion applications. The present study analyses the potential application of POMs as cathodes for MABs, as cheap alternatives to noble metal-based electrocatalysts, further considering their contribution to facing the challenges of upgrading modern energy systems into more sustainable ones. Composites of different POMs with reduced graphene oxide (POM/rGO) were synthesized and characterized in terms of their structure, surface functional groups, surface morphology, and atomic composition. Fundamental studies were carried out for five transition-metal-based POMs containing manganese, iron, cobalt, nickel, and copper, all coordinated with rGO to ascertain their viability as catalysts for the OER and ORR. Finally, laboratory-scale MABs were built and tested to maximize their power density, testing each POM to determine the most active ones. This work paves the way for using low-cost POMs as cathode electrocatalysts for rechargeable MABs, enabling the development of these devices for efficient energy storage.
Audience take away:
- The audience will deepen their understanding of electrochemical methods and novel electrocatalytic materials.
- This research shows promising results in using POMs for electrochemical conversion and storage devices.
- The work could lead to further studies on this class of materials in the field of electrochemistry or to further research on other applications for POMs.
- The study shows POMs as viable alternatives to high-cost noble-metal based electrocatalysts.
