Embedded PdFe@N-carbon nanoframes for oxygen reduction in acidic fuel cells

Carbon-supported metal nanoparticles are widely used as electrocatalysts in polymer electrolyte membrane fuel cells (PEMFCs), but still suffer from deactivation because of metal leaching and sintering at high temperature. Herein, we propose a novel and scalable metal coordination-polymer strategy for the facile synthesis of bimetallic PdFe nanoparticles embedded nitrogen-doped carbon (PdFe@N-C) nanoframes as a Mott-Schottky electrocatalyst to efficiently catalyze the oxygen reduction reaction (ORR) in PEMFCs. The metal coordination-polymer is formed through metal ions (Pd and Fe) mediated self-polymerization of 1-naphthylamine (NA), which allows alloy nanoparticles to bind tightly with N-carbon nanoframes after pyrolysis. It is found that PdFe nanoparticles with very small particle-size are uniformly embedded in the porous N-carbon nanoframes and physically separated from each other by the carbon matrix. Profited from the unique structure and composition merits, the half-wave potential of the developed PdFe@N-C nanoframes towards ORR is positively shifted by 30 and 50 mV compared to those of Pd@N-C and Pd/C, respectively. Importantly, the PdFe@N-C nanoframes derived acidic PEMFC delivers a high-power density of 0.91 W cm⁻² together with remarkable operational stability after 10 h discharging. Such good performances make the metal-NA coordination-polymer an attractive precursor to design and synthesize high-performance electrocatalysts for fuel cells.