Defect stabilized Fe atom on porous BN sheet as a potential electrocatalyst for oxygen reduction reaction: A first-principles investigation

The slow kinetics of the cathodic oxygen reduction reduction (ORR) remain a significant issue in the development of polymer electrolyte membrane fuel cells (FCs). In this study, Fe-doped porous BN (p-BN) nanosheet is proposed as an efficient and noble-metal free electrocatalyst for the ORR process in FCs using first-principles calculations. The calculated formation energies show that the Fe atom is more stable on the p-BN with a boron vacancy than one with a nitrogen vacancy. The ORR process on this electrocatalyst begins with the cleavage of the O-O bond of chemisorbed O-2, followed by the hydrogenation of the separated O atoms to produce two water molecules. The rate-determining step in the ORR process is the formation of the second H2O molecule with an energy barrier of 1.12 eV. As a result, ORR prefers a direct four-electron route on the Fe-doped p-BN catalyst. Our findings can help in the design and manufacturing of novel electrocatalysts for ORR in FCs.