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Noncloggingly Sieving Sub‑6 nm Nanoparticles of Noble Metals into Conductive Mesoporous Foams with Biological Nanofibrils

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journal contribution
posted on 16.12.2019, 20:03 by Zengbin Wang, Jie Xu, Penggang Wang, Yue Zhang, Jun You, Chaoxu Li
Porous metal foams have been one of the most sought-after materials owing to their combination of bulk metallic characteristics (e.g., thermal/electrical conductivity and ductility) and nanometric size-effect properties (e.g., catalytic reactivity, plasmonic behavior, and high surface area). Traditional sol–gel approaches, though one of the most frequently used method to produce mesoporous metal foams, were hindered for scalable production and wide applications because of its tedious multistep procedure, time-consuming gelation time, and polydisperse pore sizes. Herein, by depositing biological nanofibrils (chitin, cellulose, and silk) on commercial filtration membranes, we report a facile approach to sieve and recycle sub-6 nm nanoparticles of noble metals (Au and Pt) via nonclogging filtration into three-dimensional (3D) networks with interconnected mesopores. The porous networks could withstand air-drying, in contrast to freezing/supercritical drying conventionally used for mesoporous foams preparation. This approach was also applicable to both mesoporous monometallic (Au, Pt) and bimetallic (Au–Pt) foams. Moreover, the resultant mesoporous metallic foams show high porosity up to 90%, homogeneous mesoporous structure, and metallic conductivity up to 104 S/cm. Thus, this rapid and scalable sieving procedure not only offers a possibility of sieving noncloggingly for efficient recovery of metal nanoparticles but also starts a pathway to produce conductive and flexible mesoporous foams applicable in broad fields such as continuous flow catalysis and smart actuating.