Replacing scarce and expensive platinum (Pt) with metal–nitrogen–carbon (M–N–C) catalysts for the oxygen reduction reaction in proton exchange membrane fuel cells has largely been impeded by the low oxygen reduction reaction activity of M–N–C due to low active site density and site utilization. Herein, we overcome these limits by implementing chemical vapour deposition to synthesize Fe–N–C by flowing iron chloride vapour over a Zn–N–C substrate at 750 °C, leading to high-temperature trans-metalation of Zn–N4 sites into Fe–N4 sites. Characterization by multiple techniques shows that all Fe–N4 sites formed via this approach are gas-phase and electrochemically accessible. As a result, the Fe–N–C catalyst has an active site density of 1.92 × 1020 sites per gram with 100% site utilization. This catalyst delivers an unprecedented oxygen reduction reaction activity of 33 mA cm−2 at 0.90 V (iR-corrected; i, current; R, resistance) in a H2–O2 proton exchange membrane fuel cell at 1.0 bar and 80 °C.
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The data supporting the findings of this study are available within this Article and its Supplementary Information. Additional data are available from the corresponding authors upon reasonable request. Source data are provided with this paper.
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This work was supported by the DOE under award number DE-EE0008416 (Q.J.) and DE-EE0008075 (H.X.). We acknowledge the support from the DOE, Energy Efficiency and Renewable Energy, Hydrogen and Fuel Cell Technologies Office through the Electrocatalysis Consortium (ElectroCat) and the DOE programme and technology managers, D. Papageorgopoulos, D. Peterson and N. Garland. The ex situ XAS experiments at the Zn K edge were performed at the Advanced Photon Source, a DOE Office of Science User Facility operated for the DOE Office of Science by Argonne National Laboratory under contract no. DE-AC02-06CH11357. The operation of the Materials Research Collaborative Access Team at the Advanced Photon Source is supported by the DOE and the Materials Research Collaborative Access Team member institutions. The rest of the XAS data were collected at beamlines 6-BM, 7-BM and 8-ID (ISS) of the National Synchrotron Light Source II, a DOE Office of Science User Facility operated for the DOE Office of Science by Brookhaven National Laboratory under contract no. DE-SC0012704. AC-STEM was conducted at the Center for Nanophase Materials Sciences located at Oak Ridge National Laboratory, which is a DOE Office of Science User Facility. The submitted manuscript was created, in part, by UChicago Argonne, Operator of Argonne National Laboratory (‘Argonne’), a DOE Office of Science laboratory, operated under contract no. DE-AC02-06CH11357.
L.J., S.M. and Q.J. have filed a full patent application (no. PCT/US2020/058362) based on the results of this manuscript. The inventors are Q.J., L.J., and S.M. The application is currently pending. The CVD method for the synthesis of M–N–C catalysts is covered by this patent application. The remaining authors declare no competing interests.
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Jiao, L., Li, J., Richard, L.L. et al. Chemical vapour deposition of Fe–N–C oxygen reduction catalysts with full utilization of dense Fe–N4 sites. Nat. Mater. (2021). https://doi.org/10.1038/s41563-021-01030-2