Electronic Enhancement Engineering by Atomic Fe–N₄ Sites for Highly-Efficient PEMFCs: Tailored Electric-Thermal Field on Pt Surface

Lowering noble-metal Pt usage and simultaneously enhancing electrocatalytic oxygen reduction reaction (ORR) activity and stability of Pt-based ORR electrocatalysts is the key to realize the large-scale application of fuel cells. Here, an effective strategy is developed to reduce Pt usage through the strong electron interaction between uniform Pt nanoparticles (≈4.0 nm) and abundant atomically dispersed Fe–N₄ sites modified on an ordered mesoporous carbon (OMC) surface for efficiently enhancing ORR performance. Density functional theory (DFT) calculations show that the strong electron interactions between Pt and Fe–N₄ sites decrease the d-band center of Pt in Pt@Fe–N–OMC-2 by 0.21 eV relative to that of as-prepared Pt@OMC, indicating the weakened O₂ adsorption and accelerated desorption of oxygenated species on Pt sites. In situ Raman spectra demonstrate that the introduction of Fe–N₄ moieties promotes the O–OH dissociation process. Finite element method simulations reveal that the electric and thermal field of the embedded Pt nanoparticle surface is enhanced through modifying Fe–N₄ sites on the OMC surface, accelerating the accumulation of ORR-related species (O₂, H⁺, and H₂O), which is conductive to electrocatalyzing the ORR. This innovative approach not only illustrates the synergistic mechanism between Pt and Fe–N₄ sites, but also simultaneously provides new avenues to design advanced electrocatalysts for fuel cells. © 2023 Wiley-VCH GmbH.