Herein, the "push effect" strategy combined with "triple-phase-boundary" (TPB) engineering was innovatively employed to target the single Fe−N 4 sites in an iron porphyrinbased metal−organic framework, with axially coordinated 4octylpyridine groups on Fe−N 4 (named as PCN-224 (Fe)-1). The amphiphilic 4-octylpyridine groups donate sufficient electrons toward Fe−N 4 by the Fe−N(pyridine) coordination bond and simultaneously provide effective TBP reactive sites by the hydrophobic octyl terminals, resulting in enhanced ORR activity of the PCN-224 (Fe)-1 in hydrophobic octyl terminals, with an E 1/2 of 0.81 V and complete 4-electron selectivity. Furthermore, TPB engineering is utilized to construct the PCN-224 (Fe)-1based Zn−air battery with a maximum power density of 98 mW cm −2 , demonstrating great practical application potential for molecule-based ORR catalysts. Meanwhile, the "push effect" mechanism on ORR is revealed by electron paramagnetic resonance, in situ UV−vis spectroelectrochemical analysis, and density functional theory.
Currently, the rarity and high cost of platinum (Pt)‐based electrocatalysts seriously limit their commercial application in fuel cells cathode. Decorating Pt with atomically dispersed metal–nitrogen sites possibly offers an effective pathway to synergy tailor their catalytic activity and stability. Here active and stable oxygen reduction reaction (ORR) electrocatalysts (Pt3Ni@Ni–N4–C) by in situ loading Pt3Ni nanocages with Pt skin on single‐atom nickel–nitrogen (Ni–N4) embedded carbon supports are designed and constructed. The Pt3Ni@Ni–N4–C exhibits excellent mass activity (MA) of 1.92 A mgPt−1 and specific activity of 2.65 mA cmPt−2, together with superior durability of 10 mV decay in half‐wave potential and only 2.1% loss in MA after 30 000 cycles. Theoretical calculations demonstrate that Ni–N4 sites significant redistribute of electrons and make them transfer from both the adjacent carbon and Pt atoms to the Ni–N4. The resultant electron accumulation region successfully anchored Pt3Ni, that not only improves structural stability of the Pt3Ni, but importantly makes the surface Pt more positive to weaken the adsorption of *OH to enhance ORR activity. This strategy lays the groundwork for the development of super effective and durable Pt‐based ORR catalysts.
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