Dynamics of non-metal-regulated FeCo bimetal microenvironment on oxygen reduction reaction activity and intrinsic mechanism

The change in the coordination environment of the active sites of a fuel cell cathode catalyst provides a new modulation strategy for stimulating the catalyst’s oxygen reduction reaction activity. The thermodynamic and electronic properties of the FeCoN₅A and FeCoN₆A catalyst structures with nonmetallic A-doped (A = B, N, O, P, and S) coordination were calculated and analyzed based on density functional theory. The modulation order of G_*OH by different A-doped FeCo bimetal pairs (BMPs) was as follows: S > P > O > N/C > B. There was a dynamic distribution of charges in the coordination environment during the adsorption of OH, which resulted in inversely proportional relationship with the charge transfer between the adsorbate OH, active site, first coordination layer, and second coordination layer in turn. Descriptors of the orbital energy levels of neighboring nonmetal atoms were constructed based on the p-electron number and electronegativity of the doped nonmetal A. The change of the orbital energy levels of the first coordination atom during the adsorption process caused the structure to exhibit different adsorption energies. This study provides new insights on the non-metallic modulation of the M-N-C coordination environment to improve the oxygen reduction reaction activity.