title: pH controlled adsorption of water-soluble ruthenium clusters onto carbon nanotubes and nanofiber surfaces.
abstract: Supported catalysts were prepared from water-soluble molecular clusters by pH controlled impregnations in order to probe the interactions occurring between the supports and the clusters and to maximize them. The PZC of different nano-carbon solids (nanotubes and nanofibers) was determined. The EpHL method of measuring the PZC could be successfully extended for the first time to these nano-carbon supports. When impregnating these nano-carbons with water-soluble Ru clusters by varying the pH, we found that two adsorption mechanisms were taking place. We postulate that interactions in the form of π-bond coordination or reactions with higher reactivity zones of the carbon surface occur at all pH values. Electrostatic interactions coexist with the latter and play a determining role, allowing or hindering maximal adsorption. Our water-impregnated samples exhibit smaller and better distributed nanoparticles in comparison to an organic-solvent-impregnated sample. Sintering of the particles at higher activation temperature led to nanoparticles with a bimodal size distribution on the nanofibers. The bimodal size distribution is a strong indication of two different adsorption mechanisms. The obtained Ru/nano-C catalysts present a valuable activity and selectivity in the hydrogenation of lactose into lactitol.
authors.affiliation: Université catholique de Louvain, Institut de la Matière Condensée et des Nanosciences (IMCN), Place Louis Pasteur 1, B-1348 Louvain-la-Neuve, Belgium. sophie.hermans@uclouvain.be.
authors.forename: Nathalie
authors.initials: N
authors.lastname: Mager
authors.affiliation: Utrecht University, Inorganic Chemistry and Catalysis, Debye Institute for Nanomaterials Science, Universiteitsweg 99, 3584 CG Utrecht, The Netherlands.
authors.forename: Wouter S
authors.identifier: http://orcid.org/0000-0001-8590-564X
authors.initials: WS
authors.lastname: Lamme
authors.affiliation: Université catholique de Louvain, Institut de la Matière Condensée et des Nanosciences (IMCN), Place Louis Pasteur 1, B-1348 Louvain-la-Neuve, Belgium. sophie.hermans@uclouvain.be.
authors.forename: Samuel
authors.initials: S
authors.lastname: Carlier
authors.affiliation: Université catholique de Louvain, Institut de la Matière Condensée et des Nanosciences (IMCN), Place Louis Pasteur 1, B-1348 Louvain-la-Neuve, Belgium. sophie.hermans@uclouvain.be.
authors.forename: Sophie
authors.identifier: http://orcid.org/0000-0003-4715-7964
authors.initials: S
authors.lastname: Hermans