Synthesis of Pd–Ag Alloy Nanoframes Comprised of Hollow Ridges by Templating With Ag Nanocubes

Noble‐metal nanoframes are attractive for catalytic applications due to their open structures and large specific surface areas. However, traditional nanoframes are known to suffer from poor structural robustness because of their ultrathin ridges. Here, we address this issue by developing a new class of nanoframes characterized by relatively thick but hollow ridges. Our demonstration is based upon Pd and a typical synthesis involves the one‐shot injection of PdBr ₂ powder suspension into an aqueous mixture containing Ag nanocubes, ascorbic acid, poly(vinyl pyrrolidone), and KBr held at 75°C. The poor solubility of PdBr ₂ in water enables slow release of Pd ^(II) and thus a steady reduction rate for controlling the deposition of Pd atoms. During the synthesis, the side faces of Ag nanocubes are continuously carved away through galvanic replacement, accompanied by the deposition of Pd atoms on the corners and edges for the generation of cage cubes—cubes with through holes across the opposite faces. At a later stage, the Ag remaining in the ridges is etched away, leading to the formation of hollow ridges with a final composition of Pd ₁ Ag ₂ . The Pd–Ag alloy nanoframes exhibited good structural robustness during 1 h of chronoamperometric test toward formic acid oxidation reaction.