Design a promising electro-catalyst for oxygen reduction reaction in fuel cells based on transition metal doped in BN monolayer

Hsu C.-Y.; Ulloa N.; Naranjo Vargas E.M.; Saraswat S.K.; Saeed S.M.; Vargas-Portugal S.K.; Majdi H.S.; Lagum A.A. · International Journal of Hydrogen Energy (2024) · DOI: 10.1016/j.ijhydene.2023.08.085

Resumen

The kinetic of the oxygen reduction reaction (ORR) at the cathodes of polymer-electrolyte-membrane fuel cells (PEMFCs) has been demonstrated to be slow, which is one of the pivotal issues in developing PEMFCs. Within the current piece of research, by performing first-principles calculations, we introduce a Co-doped vacancy BN nanosheet (Co-HBN) as an efficacious noble metal-free electro-catalyst for the ORR process (ORRP) in fuel cells. The results demonstrate a rise in the energies of adsorption (or adhesion) onto the Co–N active site of these electrocatalysts in the order of O < OH < OOH < O2 < H2O2 < H2O on this electrocatalyst and there is a consistent change in the adsorption energies (Eads)for all oxygen-containing intermediates (OCIs). Based on the small and large thermodynamic driving force for the generation of H2O2 and for reducing OOH into O∗ (or to 2OH∗), respectively, the four-electron route was more favorable in comparison with the 2e− route. Furthermore, with the largest value of ΔG for Co-HBN electrocatalyst, the final reduction step (OH∗ + H+ + e− → H2O + ∗) has been regarded as the rate-limiting step. The d-band center of Co was considerably distant from the Fermi level. The greater gap between the frontier orbitals suggested that the electrocatalyst is not conducive to the adsorption of OCIs, which shows that the onset potential is larger and ORR is high.

Instituciones: Universidad Tecnológica de los Andes