Ruthenium catalyst on carbon nanofiber support layers for use in silicon-based structured microreactors, Part I: Preparation and characterization

The preparation and characterization of ruthenium catalytic nanoparticles on carbon nanofiber (CNF) support layers via homogeneous deposition precipitation (HDP) and pulsed laser deposition (PLD) is presented. Prior to ruthenium deposition the CNF layers were functionalized via liquid phase oxidation treatment using nitric acid at 90 °C. This acid treatment not only effectively removed accessible CNF-growth catalyst, but also resulted in the formation of oxygen containing functional groups on the external surface of CNFs. A variety of characterization techniques, viz. TEM, XRD, XRF, XPS, and point-of-zero-charge (PZC) measurements were used to analyze the influence of the oxidation pretreatment on physico-chemical properties of CNF layers qualitatively and quantitatively. HDP yielded a very sharp size distribution (∼85% of the particles had a diameter of 1.0–1.5 nm), whereas PLD had a less narrow distribution (the diameter of ∼75% of the particles was 1–3 nm). Both methods yielded a ruthenium loading of 2.3 ± 0.1 wt.%, and in particular HDP showed uniform anchoring of particles throughout the thickness of the CNF layer. Using optimal conditions, the space in a silicon-based microreactor channel was efficiently filled with open, entangled CNF layer, which were used as anchor points for Ru using HDP and PL