Synergy between Intermetallic Pt Alloy and Porous Co–N₄ Carbon Nanofibers Enables Durable Fuel Cells with Low Mass Transport Resistance

Abstract

The complex chemical environments and strictly limited mass transport in the catalytic layer (CL) of proton exchange membrane fuel cells (PEMFCs) seriously hinder their performance. In this study, a one-dimensional atomically dispersed Co–N4/C porous carbon nanofiber (Co–N–PCNF) supported intermetallic L10-PtCo nanoparticle is developed as an advanced PEMFC cathode via electrospinning. Thanks to the suitable pore structure and homogeneous ionomer distribution, this unique CL exhibits an excellent pressure-independent oxygen transport resistance (R O2 PI = 0.0321 s cm–1) and favorable ionomer-catalyst contact (92% dry proton accessibility) in an H2–air fuel cell. It also reveals a high initial mass activity (0.61 A mgPt –1) and extraordinary durability with MA retention of 99 and 73% after 50,000 and 100,000 cycles, respectively, exceeding the U.S. DOE 2025 targets and representing one of the most durable fuel cell catalysts ever reported. Density function theory calculations reveal that the rapid migration and decomposition of H2O2 from the Co–N4 site to L10-PtCo is the key to the accelerated oxygen reduction kinetics and the stronger binding between Co–N–PCNF and L10-PtCo compared to carbon support accounts for the much improved stability.

Engineering a High-Loading Sub-4 nm Intermetallic Platinum–Cobalt Alloy on Atomically Dispersed Cobalt–Nitrogen–Carbon for Efficient Oxygen Reduction in Fuel Cells

“…In addition, PtCo–CoNC showed a main scattering peak at ∼2.1 Å, attributed to the existence of Co–Pt/Co–Co bonds, and a shoulder peak at ∼1.4 Å, correlated with the contribution of Co–N bonds, which fitted with the Co–Co, Co–Pt, and Co–N scattering paths (Figure S15 and Table S4). Additionally, as illustrated in Figure S16, the WT analysis of Co was closely related to the EXAFS results, where the k value of a single maximum intensity was found to be lower than that of the Co foil because the Co atom coordinated with surrounding N atoms, forming a Co–N coordination structure.…”

Unraveling a volcanic relationship of Co/N/C@PtxCo catalysts toward oxygen electro-reduction

“…46,47 What should be emphasized is that the excessively decreased d band center will inversely lead to weak adsorption, not conducive to the ORR kinetics. 46,48 This may be one of the reasons for the low ORR activity of Co/N/C@Pt 1.12 Co and Co/N/C@Pt 1.55 Co catalysts (see the Pt 4f XPS spectra of other catalysts in Fig. S24–S26†).…”

“…S27–S30†). 48–50 The contents of pyrrolic and pyridinic N were plotted vs. Pt/Co ratios and are shown in Fig. 4d and e.…”

Ultradurable Pt-Based Catalysts for Oxygen Reduction Electrocatalysis

“…Therefore, the composites of carbon and metal oxides become potential candidates for promising sup- Compared with traditional carbon supports, supports embedded with single atoms are more appealing as stable supports to load Pt-based materials. The introduction of single atoms into carbon materials can not only provide a strong interaction between the supports and active metals, but also optimize the adsorption behavior of active Pt-based catalysts, enhancing the ORR performance [99][100][101]. To this end, Shao's group improved the durability of Pt nanoparticles by using the Fe-and N-codoped carbon (Fe-N-C) [102].…”