Synthesis of Free-Standing Silver Foam via Oriented and Additive Nanojoining

Silver foams with high porosity and electrical conductivity have many potential applications in energy storage, catalysis, and fuel cells. However, its application is largely hindered by the low efficiency of complicated synthesis processes. In this work, a facile and rapid bottom-up fabrication of silver foams in an aqueous solution allowing large-scale production through oriented and additive nanojoining of silver nanoplate building blocks is reported. Self-assembling of as-grown silver nanoplates facilitates the oriented nanoscale joining to align the atomic lattice, and the local additive of silver promotes diffusion and interconnection at room temperature to realize a rapid synthesis process. The freeze-dried silver foam exhibits a porosity of 95.45%, an ultralow density of 61 mg·cm^-3, low thermal conductivity of 0.29 W·m^-1·K^-1, and high electrical conductivity of 8086 S·m^-1. This oriented and locally additive nanojoining process presents a new strategy to fabricate silver foams that may also inspire the fabrications of other metal foams.