Functionalization of electrospun ceramic nanofibre membranes with noble-metal nanostructures for catalytic applications

This article reports a simple method for functionalizing the surface of TiO₂ (both anatase and rutile) and ZrO₂ nanofibre membranes with Pt, Pd, and Rh nanoparticles. The TiO₂ membranes were prepared in the form of nonwoven mats by electrospinning with a solution containing both poly(vinyl pyrrolidone) and titanium tetraisopropoxide, followed by calcination in air to generate anatase (at 510 °C) or rutile (at 800 °C). The ZrO₂ membranes were fabricated with a solution of poly(vinyl pyrrolidone) and zirconium acetylacetonate, followed by calcination in air at 550 °C to yield the tetragonal phase. The fibre mats were then immersed in a polyol reduction bath to coat the surface of the nanofibres with Pt, Pd, or Rh nanoparticles of 2-5 nm in size. In addition, the ceramic fibres decorated with Pt nanoparticles could serve as a substrate to grow Pt nanowires ∼7 nm in diameter with lengths up to 125 nm. We subsequently demonstrated the use of Pd-coated anatase fibre membranes as a catalytic system for cross-coupling reactions in a continuous flow reactor. Contrary to the conventional setup for an organic synthesis, a continuous flow system has advantages such as short reaction time and no need for separation. The membrane-based catalytic system can also be fully regenerated for reuse.