Synthesis of Platinum–Ruthenium Nanoparticles under Supercritical CO₂ and their Confinement in Carbon Nanotubes: Hydrogenation Applications

Abstract

Bimetallic platinum–ruthenium nanoparticles stabilised by pyridine‐ and monophosphine‐based ligands were prepared either in supercritical CO2 or in THF. TEM analyses evidenced a tendency of the nanoparticles prepared in supercritical CO2 to agglomerate. Both types of bimetallic nanoparticles were further confined into functionalised multiwalled carbon nanotubes. Upon confinement, PtRu nanoparticles stabilised by phosphine ligands appeared more agglomerated than those stabilised by the pyridine ligand. These materials were applied to cinnamaldehyde hydrogenation. Confined PtRu nanoparticles showed higher catalytic activity and selectivity than unsupported nanoparticles.

Untangling the Role of the Capping Agent in Nanocatalysis: Recent Advances and Perspectives

“…The creation of a confined space with high local reactant concentration and geometrical constraints directing the adsorption geometry is responsible of the high activity and selectivity of PtRu NPs inside multiwalled carbon nanotubes (MWCNTs) in the hydrogenation of cynnamaldehyde [80]. Analogously, diphenyl sulphide ligands on Pd/TiO 2 surface generate an appropriate ensemble which accommodates alkynes, but prevents the adsorption of alkenes, thus promoting the selective hydrogenation of acetylene to ethylene [81].…”

Remarkable Confinement Effect of Nanofiber in Carbon Nanotubes for Dehydrogenative Coupling of Alcohols with α‐Diaminobenzene: A Route for the Synthesis of Benzimidazoles

“…In addition, the effective confinement of Pd, Pt, Fe, Ru NPs were also observed in different organic reactions . Hetero‐bimetallic Pt−Ru NPs inside CNTs showed remarkable effect in the hydrogenation of cinnamaldehyde ,…”

Chemical reactions confined within carbon nanotubes

“…92 The early studies on palladium nanoparticles within GNF exhibited a slight shift towards the selective reduction of the CQC bond to produce hydrocinnamaldehyde. 46,47 Along with these remarkable changes to selectivity, almost all confined catalysts described showed enhanced activity as a consequence of nanoscale confinement. 45 This highlights a common challenge in the field, as direct systematic comparison across different carbon nanotubes is extremely difficult, if not impossible, due to the inherently inhomogeneous morphology and surface functionalisation of these nanostructures.…”