Bi-Continuous Nanoporous Structure Formation via Compound Decomposition

Abstract

During a dealloying process, reactive components in an alloy are selectively dissolved, leaving behind a bi-continuous porous structure composed of the remaining more noble constituents. This morphology has attracted attention in a variety of applications such as catalysis, actuation and sensing. Here, we show that similar morphologies evolve by selective dissolution of ionic and covalent compounds. Examples discussed in the work include chemical reduction of CuSO4(5H2O) to nanoporous (NP) Cu, electrochemical reduction of AgCl to NP Ag, and thermal decomposition of PbCO3 to NP PbO. These NP structures have tunable ligament size and porosity, and retain the parent compound's 3-dimensional shape and size. Since the chemical decomposition route requires no demanding alloy preparation it can serve as a convenient alternative for the manufacture of NP media for a wide spectrum of materials. Our work also unveils a fascinating hidden side of many common chemical reactions and elucidates a universal correlation between selective dissolution and the formation of self-organized bi-continuous structures.