Abstract
The proton exchange membrane fuel cell (PEMFC) as an attractive clean power source can promise a carbon-neutral future, but the widespread adoption of PEMFCs requires a substantial reduction in the usage of the costly platinum group metal (PGM) catalysts. Ultrafine nanocatalysts are essential to provide sufficient catalytic sites at a reduced PGM loading, but are fundamentally less stable and prone to substantial size growth in long-term operations. Here we report the design of a graphene-nanopocket-encaged platinum cobalt (PtCo@Gnp) nanocatalyst with good electrochemical accessibility and exceptional durability under a demanding ultralow PGM loading (0.070 mgPGM cm–2) due to the non-contacting enclosure of graphene nanopockets. The PtCo@Gnp delivers a state-of-the-art mass activity of 1.21 A mgPGM–1, a rated power of 13.2 W mgPGM–1 and a mass activity retention of 73% after an accelerated durability test. With the greatly improved rated power and durability, we project a 6.8 gPGM loading for a 90 kW PEMFC vehicle, which approaches that used in a typical catalytic converter.
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All data that support the findings of this study are available in the main text, figures and Supplementary Information files. Further data enquiries can be addressed to the corresponding authors upon reasonable request.
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Acknowledgements
Y.H., X.D., Z.Z., Z.L., A.Z., W.X. and B.P. acknowledge the Office of Naval Research (ONR) grant N00014-18-1-2155. Y.H., Z.Z., Z.L. and A.Z. acknowledge the Defense University Research Instrumentation Program (DURIP) grant N00014-18-1-2271. X.Y. and X.P. acknowledge the DOE, Office of Basic Energy Sciences, Division of Materials Sciences and Engineering grant DE-SC0014430. We acknowledge the use of facilities and instrumentation at the UC Irvine Materials Research Institute (IMRI), which is supported in part by the National Science Foundation through the UC Irvine Materials Research Science and Engineering Center (DMR-2011967). We also acknowledge assistance in additional electron microscopy characterizations by C. Wang and L. Han (UC Irvine). C. Wang, L. Han and H.L.X. acknowledge National Science Foundation grant CHE-1900401 and the TEM resources of the Center for Functional Nanomaterials (CFN), which is a US DOE Office of Science User Facility at Brookhaven National Laboratory under contract no. DE-SC0012704.
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For the experimental design and execution, the synthesis of the electrocatalysts, structural characterization, MEA fabrication and electrochemical testing were carried out by Z.Z., Z.L., A.Z., W.X. and B.P., the S/TEM and EDS characterizations by X.Y. and Z.Z. Supervision was carried out by Y.H. (conceptualization, project design, syntheses and evaluation of the catalysts), X.P. (STEM and EELS) and H.L.X. (additional EM studies). The original draft was written by Z.Z., X.D. and Y.H., and edited by Z.Z., Z.L., X.D. and Y.H.
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Patent application filed on the catalyst development as US Provisional Application no. 63/222,293 by the UCLA inventors: Y.H., X.D., Z.Z. and Z.L.; the remaining authors declare no competing interests.
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Zhao, Z., Liu, Z., Zhang, A. et al. Graphene-nanopocket-encaged PtCo nanocatalysts for highly durable fuel cell operation under demanding ultralow-Pt-loading conditions. Nat. Nanotechnol. 17, 968–975 (2022). https://doi.org/10.1038/s41565-022-01170-9
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DOI: https://doi.org/10.1038/s41565-022-01170-9
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