Rational Strain Engineering in Delafossite Oxides for Highly Efficient Hydrogen Evolution Catalysis in Acidic Media

Abstract

The rational design of hydrogen evolution reaction (HER) electrocatalysts which are competitive with platinum is an outstanding challenge to make power-to-gas technologies economically viable. Here, we introduce the delafossites PdCrO${}_2$, PdCoO${}_2$ and PtCoO${}_2$ as a new family of electrocatalysts for the HER in acidic media. We show that in PdCoO${}_2$ the inherently strained Pd metal sublattice acts as a pseudomorphic template for the growth of a strained (by +2.3%) Pd rich capping layer under reductive conditions. The surface modification continuously improves the electrocatalytic activity by simultaneously increasing the exchange current density j${}_0$ from 2 to 5 mA/cm${}_{geo}^2$ and by reducing the Tafel slope down to 38 mV/decade, leading to overpotentials ${\eta }_{10}$ < 15 mV for 10 mA/cm${}_{geo}^2$, superior to bulk platinum. The greatly improved activity is attributed to the in-situ stabilization of a $\beta$-palladium hydride phase with drastically 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 for rational surface and property engineering through the strain-stabilized formation of catalytically active phases.

References in corpus (4)

• Evidence for hydrodynamic electron flow in PdCoO${}_2$
• The properties of ultrapure delafossite metals
• Unconventional aspects of electronic transport in delafossite oxides
• Inter-planar coupling dependent magnetoresistivity in high purity layered metals

Cited by in corpus (6)

• Surface-Confined Two-Dimensional Crystal Growth on a Monolayer
• Emergent magnetism with continuous control in the ultrahigh conductivity layered oxide PdCoO2
• Adsorbate-induced formation of a surface-polarity-driven nonperiodic superstructure
• Anomalous Hall effect in electrolytically reduced PdCoO${}_2$ thin films
• Dichotomy of electron-phonon interactions in the delafossite PdCoO${}_2$: From weak bulk to polaronic surface coupling
• Layer-Resolved Many-Electron Interactions in Delafossite PdCoO2 from Standing-Wave Photoemission Spectroscopy