Nitrogen-Containing Carbon-Encapsulated Platinum Electrocatalysts Supported by Single-Walled Carbon Nanotubes for Polymer Electrolyte Fuel Cells.

Platinum (Pt)-based electrocatalysts are widely regarded as the preferred choice for oxygen reduction reaction (ORR) in Polymer Electrolyte Fuel Cell (PEFC). However, their low stability remains a critical challenge. To overcome this problem, high-crystallinity and high-purity single-walled carbon nanotubes (SWCNTs), fabricated by the enhanced direct injection pyrolysis synthesis (e-DIPS) method, are utilized as support with a nitrogen introducing treatment applied to produce nitrogen-containing SWCNT (N-SWCNT). Platinum electrocatalysts encapsulated by amorphous-carbon shell are synthesized on nitrogen-containing single-walled carbon nanotubes (Pt/N-SWCNT) using a facile and industrially favorable solution plasma (SP) method. High-resolution transmission electron microscopy observations indicate that Pt nanoparticles in Pt/N-SWCNT are encapsulated within nitrogen-containing carbon shells. As the cathodic catalyst of membrane electrode assembly (MEA) in a single cell, the Pt/N-SWCNT-MEA shows a decrease of only 20.8% in maximum power density after 16 000 cycles of the accelerated durability test (ADT). After the high-voltage acceleration (1.0-1.5 V), Pt/N-SWCNT-MEA exhibits a lower loss of 39.5%, compared to 48.3% for Pt/SWCNT-MEA and 93.2% for commercial Pt/C in maximum power density. These results indicate that nitrogen-containing carbon shells and SWCNTs as supports contribute to enhancing the stability and activity of the catalyst, thereby leading to the excellent performance of the PEFC.