Gold (Au)-based electrocatalysts used for hydrogen production via water electrolysis exhibit high chemical stability but low hydrogen evolution reaction (HER) activity. Alloying them with nickel (Ni) can improve their HER activity. A recent study investigated the HER activity and surface properties of AuNi alloy prepared on single crystal Au surfaces, revealing the atomic structural changes and surface sites responsible for enhanced HER activity of AuNi/Au catalyst during electrolysis.