Palladium nanoparticles on carbon nanotubes as catalysts of cross-coupling reactions

Abstract

The macroscopic properties of composite nanotube-nanoparticle superstructures are determined by a complex interplay of structural parameters at the nanoscale. The catalytic performance of different carbon nanotube-palladium nanoparticle catalysts, where nanoparticles were formed either directly onto nanotubes or preformed prior to deposition on nanotubes using different types of surfactants, were tested 10 in cross-coupling reactions. The decoration of multi-walled carbon nanotubes with preformed thiolatestabilised palladium nanoparticles yielded the optimum catalyst, exhibiting high activity and stability towards carbon-carbon bond formation and excellent recyclability, retaining high activity from cycle to cycle. The type of carbon nanotube support has pronounced effects on the density of deposited nanoparticles, with more polarisable MWNT able to uptake the highest number of nanoparticles per unit 15 surface area as compared to other carbon nanostructures (MWNT>DWNT>SWNT~GNF). Microscopic investigation of the nanoscale morphology found that nanoparticles increase in size during catalysis. The extent of growth is dependent on the type of nanocarbon support, with wider MWNT possessing lower curvature and thus retarding the growth and coalescence of nanoparticles to a greater extent than other carbon nanostructures (SWNT>>DWNT>MWNT~GNF). The type of halogen X in the C-X bond 20 activated by palladium appears to influence the evolution of nanoparticles during catalysis, with X=Br having the greatest effect as compared to X=Cl or I. Overall, preformed thiolate-stabilised palladium nanoparticles deposited on MWNT from solution was found to possess the most functional catalytic properties, with optimum activity, stability and recyclability in a range of cross-coupling reactions.

Immobilizing Metal Nanoparticles on Single Wall Nanotubes. Effect of Surface Curvature

“…Thus, we would expect fine palladium nanoparticles on nanotubes with larger diameters. 29 To understand the better binding of Pd nanoparticles compared to Au nanoparticles to the CNTs surfaces, we have investigated their DOS spectra plotted in Figure 6. For Pd13, the peak in the DOS spectrum that originates from the dorbitals is in the interval 0.0 eV to −1.0 eV.…”

Palladium nanoparticles on β-cyclodextrin functionalised graphene nanosheets: a supramolecular based heterogeneous catalyst for C–C coupling reactions under green reaction conditions

“…[1][2][3][4][5][6][7][8][9][10] Although a plethora of methods and reagents have been developed by considering conventional catalytic conditions, until recently the utilization of green chemistry approaches has been of pivotal importance in the light of contemporary design of synthetic processes. [1][2][3][4][5][6][7][8][9][10] Although a plethora of methods and reagents have been developed by considering conventional catalytic conditions, until recently the utilization of green chemistry approaches has been of pivotal importance in the light of contemporary design of synthetic processes.…”

Palladium nanoparticles deposited on silanized halloysite nanotubes: synthesis, characterization and enhanced catalytic property

“…Precious metals nanoparticles on catalyst supports have attracted considerable interest because they have been used in a number of catalysis applications, including transformation of organic12345 and fuel cells67891011. Reports indicate that the catalytic performance could be greatly enhanced by nanotube supports.…”