Synthesis of N‐Doped Co With the Addition of Mn and Its Bifunctional Electrocatalyst for Oxygen Reduction and Evolution in Anion Exchange Membrane‐Unitized Regenerative Fuel Cells

Co‐based bifunctional electrocatalysts were synthesized, and their performance was evaluated for bifunctional oxygen reduction reactions and oxygen evolution reactions in anion exchange membrane‐unitized regenerative fuel cells (AEM‐URFC). The crystalline structures of these catalysts were confirmed by X‐ray diffraction analysis. The surface morphology and surface elemental components revealed the homogeneous presence of Co, Mn, O, and N on the surfaces. The chemical and electronic states of Co, Co 3 O 4 , N─Co, Co 0.9 Mn 0.1 , Co 0.9 Mn 0.1 O x , and N‐doped Co 0.9 Mn 0.1 were examined through X‐ray photoelectron spectroscopy. The electrochemical bifunctional activity was analyzed using a three‐electrode rotating disk setup, and the smallest bifunctional index (BI) of approximately 0.689 V and the highest Brunauer–Emmett–Teller‐normalized specific activity were achieved (45.1 μA cm −2 at 0.8 V and 1099 μA cm −2 at 1.65 V) for N─Co 0.9 Mn 0.1 among the cobalt‐based catalysts. Furthermore, it exhibited a current density of 140 mA cm −2 at 0.5 V in fuel cell mode and 97.5 mA cm −2 at 2.2 V in water electrolyzer mode in AEM‐URFCs. N─Co 0.9 Mn 0.1 showed the highest catalytic performance due to its optimized high surface area, lower charge transfer resistance, and conducting N‐doped metal catalysts.