Composition control of alloy nanoparticles consisting of bulk-immiscible Au and Rh metals an ionic liquid/metal sputtering technique for improving their electrocatalytic activity.

AuRh bimetallic alloy nanoparticles (NPs) were successfully prepared by simultaneous sputtering of Au and Rh in a room-temperature ionic liquid (RTIL) of ,-diethyl--methyl--(2-methoxyethyl) ammonium tetrafluoroborate (DEME-BF). Bimetallic AuRh alloy NPs of 1-2 nm in size were formed in the RTIL. The alloy composition was controllable by changing the surface areas of Au and Rh plates used as sputtering targets.