Transformation of Single Ag Nanowires into Super‐Large AgAu Elliptic Rings via a Water/Oil Interface‐Oriented Asymmetrical Etching

Abstract Nanoring as one of fascinating geometries exhibits unique size‐dependent physical and chemical properties endowed by its circular feature. However, to the best of our knowledge, super‐large elliptical nanorings cannot be fabricated by the existing techniques. Herein, we successfully fabricated super‐large elliptical AgAu nanorings creatively by splitting single Ag nanowires along their longitudinal axes involving oil/water interfacial self‐assembly of Ag nanowires and the galvanic replacement between interfacial Ag nanowires and AuCl₄⁻ located in the water phase. The formation of AgAu nanoring is mainly attributed to the local nanomasking of Au atoms and asymmetrical etching on interfacial Ag nanowire. Additionally, as‐prepared super‐large elliptical AgAu nanorings with rough surfaces exhibit enhanced catalytic performance towards the reduction of p‐nitrophenol due to the combination of the compositional and structural effects. This strategy, without doubt, provides a convenient way for precisely carving nanoparticles, and has the potential for processing other metallic or non‐metallic nanoparticles.