Triggering Synergistic Electronic Effect via Electron‐Directed Transfer within Pt_NPs‐Fe/NC Oxygen Reduction Catalyst for Zinc‐Air Batteries

Rationally tuning Fe-N-C catalysts with synergistic nanoparticles for efficient oxygen reduction reaction (ORR) still remains challenging. Here, a nitrogen-doped carbon-supported bimetallic catalyst (Pt_NPs-Fe/NC), combining atomically dispersed Fe-N-C sites with Pt nanoparticles, is synthesized. Experimental results reveal a directional electron transfer between Pt nanoparticles and Fe sites, which induces an electron synergistic effect, effectively modulating the electron density around the Fe sites. The modulation significantly enhances the ORR catalytic activity of Pt_NPs-Fe/NC. As a result, Pt_NPs-Fe/NC displays a half-wave potential of 0.901 V (versus RHE) and a Tafel slope of 59 mV dec^-1, surpassing the performance of commercial Pt/C and demonstrating accelerated reaction kinetics. In the meantime, Pt_NPs-Fe/NC maintains excellent durability in terms of stability as well. When assembled into liquid zinc-air batteries (ZABs), Pt_NPs-Fe/NC delivers a peak power density of 201.48 mW cm^-2 and a specific capacity of 809 mAh g^-1. Additionally, Pt_NPs-Fe/NC-based flexible ZABs display outstanding discharge performance and cycling stability. This work highlights the effectiveness of multiscale catalytic sites in advancing ORR catalyst performance and provides valuable insights into the construction strategies of catalysts for energy storage applications.