The rational design of hydrogen evolution reaction electrocatalysts that can compete with platinum is an outstanding challenge in the process of designing viable power-to-gas technologies. Here, we introduce delafossites as a family of hydrogen evolution reaction electrocatalysts in acidic media. We show that, in PdCoO2, the inherently strained Pd metal sublattice acts as a pseudomorphic template for the growth of a tensile-strained Pd-rich capping layer under reductive conditions. The surface modification ranges up to 400 nm and continuously improves the electrocatalytic activity by simultaneously increasing the exchange current density and by reducing the Tafel slope down to 38 mV dec−1, leading to overpotentials η10 < 15 mV. The improved activity is attributed to the operando stabilization of a β-PdHx phase with enhanced surface catalytic properties with respect to pure or nanostructured palladium. These findings illustrate how operando-induced electrodissolution can be used as a top-down design concept through the strain-stabilized formation of catalytically active phases.
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We gratefully acknowledge P. Schützendübe and M. Wieland for the XPS measurements, and E. Frau and P. Iyengar for the introduction to and assistance with the SECM measurements. Y. Eren Suyolcu, A. Bandarenka, N. Vargas-Barbosa, and especially R. Merkle are acknowledged for fruitful discussions. We further acknowledge C. Hohmann (NIM) for creating the figure in the table of contents. E.A.-L. acknowledges support from the SNF Ambizione Energy programme and the research programme of FOM, which is financially supported by the Netherlands Organisation for Scientific Research (NWO). S.Z. and C.S. acknowledge financial support from the German Research Foundation (DFG) under the priority programme SPP 1613 (DFG SCHE 634/12-2). B.V.L. acknowledges the Cluster of Excellence e-conversion. F.P., E.A.-L., B.V.L. and A.F.i.M. thank the MPS-EPFL Center for financial and logistic support.
The authors declare no competing interests.
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Podjaski, F., Weber, D., Zhang, S. et al. Rational strain engineering in delafossite oxides for highly efficient hydrogen evolution catalysis in acidic media. Nat Catal 3, 55–63 (2020). https://doi.org/10.1038/s41929-019-0400-x
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