Fe–N–C Boosts the Stability of Supported Platinum Nanoparticles for Fuel Cells

Abstract

The poor durability of Pt-based nanoparticles dispersed on carbon black is the challenge for the application of long-life polymer electrolyte fuel cells. Recent work suggests that Fe- and N-codoped carbon (Fe–N–C) might be a better support than conventional high-surface-area carbon. In this work, we find that the electrochemical surface area retention of Pt/Fe–N–C is much better than that of commercial Pt/C during potential cycling in both acidic and basic media. In situ inductively coupled plasma mass spectrometry studies indicate that the Pt dissolution rate of Pt/Fe–N–C is 3 times smaller than that of Pt/C during cycling. Density functional theory calculations further illustrate that the Fe–N–C substrate can provide strong and stable support to the Pt nanoparticles and alleviate the oxide formation by adjusting the electronic structure. The strong metal–substrate interaction, together with a lower metal dissolution rate and highly stable support, may be the reason for the significantly enhanced stability of Pt/Fe–N–C. This finding highlights the importance of carbon support selection to achieve a more durable Pt-based electrocatalyst for fuel cells.

A General and Scalable Approach to Sulfur-Doped Mono-/Bi-/Trimetallic Nanoparticles Confined in Mesoporous Carbon

“…Porous carbon supported metal nanoparticles are among the most studied catalysts, which have been employed in various heterogeneous catalytic reactions. − It has been well proven that supporting metal nanoparticles on the porous carbon materials with high surface area can significantly enhance the catalytic efficiency. However, catalyst deactivation often occurs due to the thermodynamical instability of metal nanoparticles and their weak interaction with carbon supports, − which represent the major obstacles for practical applications.…”

Inactive Metallic Particles Inhibit the Demetalization of Single-Atom Iron During Oxygen Reduction for Durable Fuel Cell Operation

“…As shown in Fig. 1d and 1e, the integrated negative of the projected crystal orbital Hamilton population (-ICOHP) increased from 2.517 to 2.644 after Pt loading, corresponding to a higher Fe-N bond strength 25,26 . The result proposed that the Pt particle increased the electron density at the FeN4 position, preferentially enlarging the bonding component and consequently strengthening the Fe-N bond 12 .…”

“…The larger N implied a higher electron density at the Fe center, corresponding to a lower Fe valence 12,27 . The higher -ICOHP corresponded to a stronger Fe-N bond 25,26 . The observed positive correlation strongly supported that the metallic particles, as electron donors, increased the electron density at the FeN4 position and strengthened the Fe-N bond.…”

“…Therefore, the above experiments confirmed that the inactive Pt particles inhibited the dissolution of single-atom Fe and significantly boosted the catalyst durability. Previously, Shao et al proposed that the FeN4 site inhibited the dissolution of Pt in a Pt@FeN4 catalyst 26 . The focus was on the stability promotion of the FeN4 site on Pt particles, different from the viewpoint proposed in this study.…”

Single-atom catalysts for electrochemical applications

“…90 More strategies tend to combine Pt-based alloys and single-atom catalysts synergistically to achieve an efficient ORR under acid conditions. [91][92][93] As for ORR, the majority of the electrochemical ORR proceeds through a direct four-electron transfer pathway by reducing O 2 to OH-or H 2 O as final products in a basic or acidic solution. However, the rest of the electrochemical ORR proceeds with twoelectron transfer by reducing O 2 to H 2 O 2 .…”