Activity Restoration of Pt-Ni Octahedron via Phase Recovery for Anion Exchange Membrane-Unitized Regenerative Fuel Cells

Abstract

Unitized regenerative fuel cells (URFCs) offer a cost-effective solution for energy conversion by functioning as both fuel cells and electrolyzers. Anion-exchange membrane-based URFCs (AEM-URFCs) require bifunctional electrocatalysts, such as Pt-Ir alloys, for the oxygen evolution reaction (water electrolysis mode) and oxygen reduction reaction (fuel cell mode). However, the low stability of Pt in alkaline media and the high cost of Ir remain challenges for the widespread application of these URFCs. In this study, a Pt-Ni octahedral alloy is synthesized to replace Ir with Ni as the oxygen evolution reaction catalyst. The alloying effect of Pt-Ni inhibits the dissolution of Pt and transforms PtOx to metallic Pt via a recovery process, thereby providing a new operational strategy for improving the durability of AEM-URFCs. Remarkably, the performance of the AEM-URFC single cell is maintained over ten cycles after the recovery process, demonstrating the viability of this approach for long-term operations. These findings pave the way for broader applications and advancements of AEM-URFCs. This study unveils the underlying mechanism of Pt-Ni octahedron activity restoration as a new strategy to enhance durability for anion exchange membrane-based unitized regenerative fuel cells (AEM-URFCs). An alkaline electrolyte induces nickel oxide passivation on (111) facet of Pt-Ni octahedron to reduce the dissolution of Pt, demonstrating the stable operation of AEM-URFCs single cell over 10 cycles with the recovery process.image