Freezing-Mediated Synthesis and Applications of Porous Metals

Abstract

Porous metals combine the physicochemical properties of metals and structural features of porous materials, which are characterized as a special class of materials promising in various fields such as tissue engineering, energy storage and conversion, electronics, and sensing. Among diverse fabrication approaches, freezing-mediated synthesis (e.g., freeze-casting and freeze-thawing) stands out due to its strong controllability over meso-to-macroscales as well as environmental friendliness. Many efforts have been made in the past few decades, yielding a library of porous metals featuring different building blocks (feature size and dimension), morphologies, and compositions by identifying and optimizing synthetic parameters. However, a deep understanding of the ice–matter interactions is limited, which becomes more pronounced when the processed system transforms from micrometer to nanometer size. Therefore, an overview and deep analysis for the freezing-mediated fabrication of porous metals are essential. This review first introduces the history of freezing-mediated synthesis of porous metals, followed by the fundamentals of the freezing process and design strategies. Afterward, the freezing-mediated fabrication of porous metals is summarized from the aspect of their building blocks, followed by the application explorations of those special-structure metals. Finally, the challenges and opportunities are concluded to guide future research in designing advanced porous metals by freezing-based approaches.