Plasma-enabled synthesis of ordered PtFe alloy nanoparticles encapsulated with ultrathin N-doped carbon shells for efficient methanol electrooxidation

Methanol oxidation reaction (MOR), the key reaction for clean energy generation in fuel cells, is kinetically sluggish and short-lasting because of insufficient catalytic activity and stability of the common Pt-based electrocatalysts. Ordered Pt alloy structures which promise to surmount these issues, are challenging and impractical to fabricate using common high-temperature annealing. To address the urgent need for simple and rapid synthesis methods for such alloys, here we report the versatile plasma-assisted thermal annealing synthesis of a robust electrocatalyst with PtFe alloys supported on N-doped carbon nanotubes (denoted as PtFe@NCNT-P). Benefiting from the reactive plasma-specific effects, the PtFe@NCNT-P electrocatalyst features ultrafine PtFe alloy nanoparticles (mean size ~ 2.88 nm, ordered degree ~ 87.07%) and ultrathin N-doped carbon (NC) shells (0.3–0.7 nm), leading to the excellent catalytic activity and stability toward MOR. The catalyst shows the specific and mass activities of 3.99 mA/cm² and 2,148.5 mA/mg, which are 7.82 and 7.41 times higher than those for commercial Pt/C (0.51 mA/cm², 290 mA/mg), and 2.18 and 2.59 times higher compared to the plasma-untreated PtFe@NCNT (1.83 mA/cm², 829.5 mA/mg), respectively. The PtFe@NCNT-P further exhibits extraordinary stability during the long-term chronoamperometry test and 1,000-cycle cyclic voltammetry scanning, much better compared to PtFe@NCNT samples even after the longer thermal annealing. These findings show great potential of the plasma-enabled synthesis of high-performance carbon-supported metallic electrocatalysts for the emerging clean energy technologies.