Petrified Hollow Fiber Membranes with Hierarchical Pores

Porous oxide hollow fiber membranes are broadly useful for filtration and chemical separation. They are traditionally formed by phase inversion-sintering above 1200 °C, which is expensive limiting their large-scale applications. Inspired by the natural wood petrification process, we report fabrication of porous oxide hollow fiber membranes via petrification of polymer hollow fiber templates at a much lower temperature (600 °C). These novel petrified hollow fiber membranes reproduce the asymmetric macropore structure of their polymer hollow fiber templates, thereby allowing rejection of macromolecular solutes without a secondary coating layer. They have a unique hierarchical micro-/meso-/macroporous structure with simultaneous high surface area and large pore volume. The findings of this work pave the way for wider applications of porous oxide membranes. More broadly, they allow simple and inexpensive control of the geometry of hierarchically porous oxides.