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Improving Pd–N–C fuel cell electrocatalysts through fluorination-driven rearrangements of local coordination environment

Abstract

The local coordination environment around catalytically active sites plays a vital role in tuning the activity of electrocatalysts made of carbon-supported metal nanoparticles. However, the rational design of electrocatalysts with improved performance by controlling this environment is hampered by synthetic limitations and insufficient mechanistic understanding of how the catalytic phase forms. Here we show that introducing F atoms into Pd/N–C catalysts modifies the environment around the Pd and improves both activity and durability for the ethanol oxidation reaction and the oxygen reduction reaction. Our data suggest that F atom introduction creates a more N-rich Pd surface, which is favourable for catalysis. Durability is enhanced by inhibition of Pd migration and decreased carbon corrosion. A direct ethanol fuel cell that uses the Pd/N–C catalyst with F atoms introduced for both the ethanol oxidation reaction and oxygen reduction reaction achieves a maximum power density of 0.57 W cm−2 and more than 5,900 hours of operation. Pd/C catalysts containing other heteroatoms (P, S, B) can also be improved through the addition of F atoms.

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Fig. 1: Schematic illustration of the fluorination-driven rearrangement of the LCE.
Fig. 2: Structural characterization by Fourier-transform infrared spectra, Raman spectra, electrical conductivity and ultraviolet photoelectron spectroscopy (UPS).
Fig. 3: Morphology and atomic structure of Pd/X–F catalysts.
Fig. 4: Spectroscopic analyses by XAS.
Fig. 5: Electrochemical ORR and EOR performance.
Fig. 6: Direct ethanol fuel cell tests and stability.
Fig. 7: DFT calculations.

Data availability

The authors declare that all data supporting the findings of this study are available within the paper and Supplementary Information files. Source data are provided with this paper.

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Acknowledgements

This work was supported by a start-up grant from the University of Central Florida. J.C. acknowledges financial support from the Preeminent Postdoctoral Program (P3) at the University of Central Florida. The XPS test was supported by the US National Science Foundation (Division of Electrical, Communications and Cyber Systems, no. 1726636), hosted in the Materials Characterization Facility and Advanced Materials Processing and Analysis Center, Department of Materials Science and Engineering, College of Engineering and Computer Science, University of Central Florida. Z.F. acknowledges support from the US National Science Foundation (National Nanotechnology Coordinated Infrastructure, no. 2025489). Guofeng Wang and B.L. acknowledge support from the US National Science Foundation (Division of Chemical, Bioengineering, Environmental and Transport Systems, no. 1804534). Computational resources were provided by the University of Pittsburgh Center for Research Computing as well as the Extreme Science and Engineering Discovery Environment, which is supported by National Science Foundation grant no. ACI-1053575. The use of the Advanced Photon Source at Argonne National Laboratory for XAS measurements at beamlines 5-BM and 12-BM was supported by the US Department of Energy under contract no. DE-AC02-06CH11357. DuPont-Northwestern-Dow Collaborative Access Team (DND-CAT) is supported through E. I. duPont de Nemours and Company, Northwestern University and the Dow Chemical Company. M.G. acknowledges support from the Guangdong Innovative and Entrepreneurial Research Team Program (grant no. 2019ZT08C044) and the Peacook Team Program supported by the Science, Technology and Innovation Commission of Shenzhen Municipality (KQTD20190929173815000).

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Contributions

Y.Y. led the project and proposed the concept. J.C. designed and performed most of the experiments and analysed most of the data. Guanzhi Wang performed the X-ray diffraction, XPS and UPS characterizations. W.Z. performed the NMR test. Q.W., Y.Z. and M.G. carried out the electron microscopy analysis. M.O. and N.O. performed the Raman tests. M.W., Q.M., H.Z. and Z.F. collected and analysed the XAS data. B.L. and Guofeng Wang performed the DFT calculations. J.C. and Y.Y. wrote the paper. All authors discussed the results and revised the paper together.

Corresponding authors

Correspondence to Meng Gu, Zhenxing Feng, Guofeng Wang or Yang Yang.

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Competing interests

The fluorinated fuel cell catalysts disclosed in this work have been filed as US Provisional Patent Application (Serial No. 63/260,768) with Y.Y. and J.C. as inventors. The status of the patent application is pending.

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Peer review information Nature Energy thanks Wenzhen Li and the other, anonymous, reviewer(s) for their contribution to the peer review of this work.

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Supplementary information

Supplementary Information

Supplementary Figs. 1–63, Tables 1–8, Notes 1–5 and references.

Supplementary Data 1

Source data for Supplementary Figs. 36a–c, 44d, 49, 50e, 51d, 55, 58j and 59c.

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Statistical source data.

Source Data Fig. 5

Statistical source data.

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Chang, J., Wang, G., Wang, M. et al. Improving Pd–N–C fuel cell electrocatalysts through fluorination-driven rearrangements of local coordination environment. Nat Energy 6, 1144–1153 (2021). https://doi.org/10.1038/s41560-021-00940-4

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