Nanoporous Palladium–Silver Surface Alloys as Efficient and pH-Universal Catalysts for the Hydrogen Evolution Reaction

Developing electrocatalysts that are more efficient and robust than platinum for pH-universal hydrogen evolution reaction (HER) is crucial for scalable and sustainable hydrogen production through electrochemical water splitting. Here we report platinum-free bimetallic surface alloys of palladium and silver, which spontaneously form on self-supported three-dimensional nanoporous Pd–Ag–Al electrodes during the selective etching process, as high-performance HER catalysts in both basic and acidic media. As a consequence of Ag weakening moderately the hydrogen bonding energy of nearby surface Pd atoms to improve HER intrinsic activity and interconnective metal skeleton facilitating electron transfer, nanoporous Pd–Ag–Al electrodes exhibit low onset overpotential and ultralow Tafel slopes (∼26 and ∼56 mV dec–1) and overpotentials (∼63 and ∼108 mV) at 200 mA cm–2 in 0.5 M H2SO4 and 1 M KOH electrolytes, respectively, with long-term cycling stability. The catalytic properties make them attractive alternatives to Pt-based catalysts toward highly efficient HER.