All-Solid-State Confinement Synthesis of PtFe Alloy Anchored on N-Doped Carbon for Acidic Oxygen Reduction.

Pt-based alloy catalysts have been established as highly active and robust oxygen reduction reaction (ORR) electrocatalysts in the practical proton exchange membrane fuel cell (PEMFC). Nevertheless, fabricating such catalysts with low Pt loading via low-cost, solvent-free, and size-controllable synthetic protocols remains an open space to be explored. Herein, we combined an all-solid-state synthesis of ZIF-8 precursor with a direct confined pyrolysis for the uniform anchoring of PtFe alloy nanoparticles on nitrogen-doped carbon derived from ZIF-8 (PtFe/NC). The resulting PtFe/NC catalyst with only 1.59 wt % Pt exhibits a remarkable half-wave potential of 0.897 V and a mass activity of 2.34 A mgPt-1 (@0.90 V, iR-free), outperforming commercial 20 wt % Pt/C (0.14 A mgPt-1) by a factor of 17. We have confirmed that Fe doping can effectively restrict the growth of Pt particles. Meanwhile, integrating Fe atoms into the Pt lattice results in a 3.6% lattice compression, which correspondingly downshifts the d-band center and optimizes the adsorption strength toward reaction intermediates, thereby facilitating oxygen release and significantly enhances the catalytic activity.