Integrated Metal–Air Battery and Selective Electrolytic Leaching Cell for the Preparation of Nanoporous Metals

Abstract

Electrolytic cells are used in various electrochemical applications to drive nonspontaneous chemical reactions through electrical energy supply. A typical application in nanofabrication involves the synthesis of nanoporous materials by selective electrolytic leaching, during which an electrical bias voltage is used to drive the removal of sacrificial elements. Here we report on an electrolytic cell configuration that can do the selective leaching work without the need of external electrical energy, taking advantage of two phenomena: On one hand, during the “spontaneous” discharge of a metal–air battery, materials are removed from the anode; on the other hand, during nanofabrication by “nonspontaneous” selective leaching, sacrificial elements are removed from the starting material. We integrate these two processes in such a way that both “battery discharging” and “selective leaching” occur simultaneously. Here we have demonstrated the concept through the fabrication of nanoporous Au by selective leaching of Ag from Au/Ag parent materials in a nonoxidizing aqueous solution, a process that absolutely requires an electrical energy to drive the removal of Ag. In our integrated cell configuration, no external electrical energy was used. This new concept can be extended to the fabrication of a broad range of nanoporous materials under mild conditions, including the use of pure water as electrolyte as demonstrated in this work.