Controlled synthesis of highly dispersed and nano-sized Ru catalysts supported on carbonaceous materials via supercritical fluid deposition

Abstract

Highly dispersed Ru nanoparticles (NPs) supported on carbonaceous materials were fabricated by supercritical fluid deposition technology and characterized by various methods including high-resolution transmission electron microscopy (HRTEM), and X-ray photoelectron spectroscopy (XPS). The mean particle size was controlled in the range from 0.42 to 3.66 nm by changing the carbonaceous support or the pretreatment method of the supports. Ru NPs supported on carbon nanotubes (CNTs) presented smaller particle size, higher dispersion and catalytic activity than those on activated carbon (AC). The interactions between Ru precursors and different carbonaceous supports were characterized by hydrogen temperature programmed reduction (TPR). The ultrasonication-assisted nitric acid oxidation pretreatment method for CNTs is favorable for the dispersion of Ru NPs. The appropriate ultrasound time and the dosage of nitric acid are the prerequisites of its good performance. The optimized pretreatment conditions are ultrasound time 20 min and nitric acid dosage 1/14 (the mass ratio of CNTs to HNO₃).