Control of Oxidative Etching Rate of Cu Nanocubes in Synthesis of CuRu Nanocages and Nanoframes

Cu is an ideal candidate for the sacrificial template to obtain hollow nanostructures because of its abundency and price compared with noble metals. However, the rapid oxidative etching rate of Cu is an obstacle when tailoring the morphology of hollow nanostructures. We use Cu nanocubes as a sacrificial template to obtain CuRu nanocages and nanoframes by controlling the oxidative etching rate of Cu nanocubes through the Ar flow rate. The oxidative etching of Cu nanocubes begins from the [110] direction and transforms from a cube (enclosed by six {200} facets) to a rhombicuboctahedron (enclosed by six {200}, eight {111}, and 12 {220} facets). The CuRu nanocages are obtained through the deposition of Ru atoms on all facets of the rhombicuboctahedron followed by diffusion or substitution into the surface to form alloyed CuRu layers from the slow oxidative-etched Cu nanocubes at an Ar flow rate of 20 mL/min. The CuRu nanoframes are obtained through the deposition of Ru atoms only on the {200} and {111} facets of the rhombicuboctahedron followed by diffusion or substitution into the surface to form alloyed CuRu layers from the fast oxidative-etched Cu nanocubes at an Ar flow rate of 10 mL/min.