Plasma-enabled synthesis of ordered PtFe alloy nanoparticles encapsulated with ultrathin N-doped carbon shells for efficient methanol electrooxidation
Xuxu Sun, Zhijian Mao, Ruiqi Wang, Xiaohu Pi, Changle Chen, Junbo Zhong, Qi Wang, Kostya Ostrikov
Abstract
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.