Fabrication of hollow metallic copper particles using a standard electrode potential difference

Hollow metallic particles have a lower density than their bulk counterparts with an equivalent apparent volume; therefore, they are expected to be applied in fields requiring low density and large surface area materials. This study proposes a method for synthesizing hollow metallic Cu particles in an aqueous solution. An aqueous suspension of hollow metallic Cu particles was prepared by placing metallic Zn particles in an aqueous Cu acetate solution. Based on the displacement plating related to the standard electrode potential difference between Cu and Zn, Cu²⁺ ions were reduced to metallic Cu by receiving electrons from metallic Zn, while metallic Zn dissolved into the aqueous solution. Consequently, metallic Cu with a shell-like shape formed near the surface of the original metallic Zn particles before Zn dissolution, yielding hollow metallic Cu particles. Thus, this study revealed that the Cu acetate concentration should be appropriately controlled to fabricate hollow particles. Moreover, the developed method can easily fabricate hollow metallic particles in one step without adding external reducing agents.