Solid-solution alloy nanoparticles of a combination of immiscible Au and Ru with a large gap of reduction potential and their enhanced oxygen evolution reaction performance

Au and Ru are elements that are immiscible in the bulk state and have the largest gap in reduction potential among noble metals. Here, for the first time, Au(x)Ru(1–x) solid-solution alloy nanoparticles (NPs) were successfully synthesized over the whole composition range through a chemical reduction method. Powder X-ray diffraction and scanning transmission electron microscopy coupled with energy-dispersive X-ray spectroscopy showed that Au and Ru atoms are homogeneously mixed at the atomic level. We investigated the catalytic performance of Au(x)Ru(1–x) NPs for the oxygen evolution reaction, for which Ru is well known to be one of the best monometallic catalysts, and we found that even alloying with a small amount of Au could significantly enhance the catalytic performance.