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.