Carbon-encapsulated PtPd alloy electrocatalysts on single-walled carbon nanotubes for durable polymer electrolyte fuel cells

Abstract

Highly crystalline single-walled carbon nanotubes were employed as robust supports for carbon-encapsulated PtPd alloy electrocatalysts synthesized via a rapid, industrially scalable solution plasma method, enhancing long-term durability under frequent start-up/shut-down conditions. Electrochemical evaluation of PtPd@C/SWCNT as a cathode catalyst in a polymer electrolyte fuel cell (PEFC) membrane electrode assembly (MEA) demonstrated superior durability compared to commercial Pt/C and monometallic Pt@C/SWCNT under an accelerated durability test. PtPd@C/SWCNT maintained high performance for 5000 potential cycles and retained over 50% of its electrochemically active surface area (ECSA) after 10 000 cycles under the accelerated durability test of high-potential triangular pulses (1.0–1.5 V) simulating harsh conditions encountered during actual start-up/shut-down operations. Carbon encapsulation effectively inhibited nanoparticle agglomeration and suppressed the oxidation of the SWCNT support in close proximity to the nanoparticles during the durability test of 30 000 cycles. Raman spectroscopy confirmed the excellent corrosion resistance and maintained the crystallinity of the SWCNT support. The negligible thickness change observed in the PtPd@C/SWCNT cathode layer further highlights the benefit of the SWCNT support and carbon encapsulation in maintaining structural integrity under severe operating conditions. XPS analysis indicated a more stable, reduced state of Pt in PtPd@C/SWCNT compared to that of Pt/C. These results highlight the synergistic effects of the SWCNT support and carbon encapsulation in improving both catalyst stability and support durability for prolonged PEFC operation, particularly under demanding heavy-duty vehicle (HDV) conditions.