Nanometer-thick defective graphene films decorated with oriented ruthenium nanoparticles. Higher activity of 101 vs 002 plane for silane-alcohol coupling and hydrogen transfer reduction

Abstract

Pyrolysis of ammonium alginate films containing Ru(NH3)6Cl3 leads to the formation of Ru nanoparticles (NPs) supported on defective graphene films. The procedure allows controlling the preferential facet orientation of small Ru NPs (5–20 nm), either 002 when the pyrolysis is carried out under Ar atmosphere or the 002 and 101 planes for pyrolysis in the presence of H2. Ru is a metal difficult to prepare in preferential facet orientation compared to noble metals due to its higher reactivity and smaller particle size. Theoretical calculations substantiated the inhibition of Ru(002) growth by H2 adsorption, with restructuration to Ru(002–101) NPs. The defective graphene films of about 15 nm thickness containing one of the two types of Ru NPs (150 ng/cm2) exhibit distinctive catalytic activity for the dehydrogenative coupling of silanes and alcohols and hydrogen transfer reduction of cyclohexanone. Comparison of turnover frequencies indicates that the 101 facet is more efficient than the 002 plane. Overall, this study illustrates that pyrolysis conditions can control the preferential crystallographic orientation of the growing Ru NPs and the relative catalytic activity of their specific crystallographic planes.