Halloysite nanotubes sponges with skeletons made of electrospun nanofibers as innovative dye adsorbent and catalyst support

Naturally existing Halloysite nanotubes (HNTs) are promising dye adsorbent and catalyst support; however, to directly use the HNTs powder encounters a practical problem related to separation and regeneration. In this work, highly porous HNTs sponges (with weight ratios of nanofibers-to-HNTs being 1:2, 1:4, 1:6, and 1:8) were prepared via a facile while innovative approach (i.e., homogenizing the HNTs-PVA-nanofibers suspension, fast freezing, freeze drying, and thermal stabilization). In these sponges, short electrospun polyacrylonitrile and polyimide nanofibers acted as skeletons, supported HNTs, and provided mechanical elasticity and stability, while poly(vinyl alcohol) was utilized as binding agent. The HNTs sponges with nanofibers-to-HNTs weight ratio of 1:8 had low density (43.4 mg/cm(3)), high porosity (97.9%), large BET surface area (25.0m(2)/g), excellent mechanical elasticity, good thermal stability, and high HNTs loading amount (88.9%), and they demonstrated high performances as novel dye adsorbent and catalyst support. This work would not only provide a novel approach for the preparation of HNTs sponges but also expand the applications of three-dimensional sponges/structures made of short electrospun nanofibers.