Pd2+-exchanged graphite oxide and chemically derived graphenes therefrom were employed as supports for Pd nanoparticles. The influence of catalyst preparation, carbon functionalization, and catalyst morphology on the catalytic activity in the Suzuki−Miyaura coupling reactions was investigated. The catalysts were characterized by means of spectroscopy (FT-IR, solid-state 13C NMR, AAS, XPS), X-ray scattering (WAXS), surface area analysis (BET, methylene blue adsorption), and electron microscopy (TEM, ESEM). In contrast to the conventional Pd/C catalyst, graphite oxide and graphene-based catalysts gave much higher activities with turnover frequencies exceeding 39 000 h−1, accompanied by very low palladium leaching (<1 ppm).

Palladium Nanoparticles on Graphite Oxide and Its Functionalized Graphene Derivatives as Highly Active Catalysts for the Suzuki−Miyaura Coupling Reaction

X-ray photoelectron spectroscopy: Towards reliable binding energy referencing

Functionalization of atomically thin nanomaterials enables the tailoring of their chemical, optical and electronic properties. Exfoliated black phosphorus (BP)-a layered two-dimensional semiconductor-exhibits favourable charge-carrier mobility, tunable bandgap and highly anisotropic properties, but it is chemically reactive and degrades rapidly in ambient conditions. Here we show that covalent aryl diazonium functionalization suppresses the chemical degradation of exfoliated BP even after three weeks of ambient exposure. This chemical modification scheme spontaneously forms phosphorus-carbon bonds, has a reaction rate sensitive to the aryl diazonium substituent and alters the electronic properties of exfoliated BP, ultimately yielding a strong, tunable p-type doping that simultaneously improves the field-effect transistor mobility and on/off current ratio. This chemical functionalization pathway controllably modifies the properties of exfoliated BP, and thus improves its prospects for nanoelectronic applications.

Covalent functionalization and passivation of exfoliated black phosphorus via aryl diazonium chemistry

The present invention relates to a novel process for the preparation of a reusable heterogeneous nanopalladium (0) catalysts, which is a eco-friendly and economical process employing re-usable heterogeneous catalyst in place of soluble palladium catalysts for preparing coupling products by C—C bond formation reaction of haloarenes that include unreactive chloroarenes in the presence of base. The use of heterogeneous nanopalladium catalyst precludes the presence of palladium in traces with the product.

Layered double hydroxides supported nanopalladium catalysts for Heck-, Suzuki, Sonogashira-, and Stille type coupling reactions of haloarenes

This paper describes a simple and versatile method for growing highly anisotropic nanostructures of Pd, single-crystal nanobars bounded by {100} facets and single-crystal nanorods with their side surfaces enclosed by {100} and {110} facets. According to thermodynamic arguments, Pd atoms should nucleate and grow in a solution phase to form cuboctahedrons of spherical shape with their surfaces bounded by a mix of {111} and {100} facets. Anisotropic nanostructures can only form under kinetically controlled conditions, while the cubic symmetry is broken. In the present system, we found that one-dimensional growth could be induced and maintained through an interplay of the following processes: (i) speedy reduction of the precursor to ensure prompt addition of atoms to the seed; (ii) chemisorption of bromide on the seed to promote the formation of {100} and {110} facets; and (iii) localized oxidative etching on one specific face of the seed to initiate preferential growth on this face. Experimentally, the anisotropic growth can be achieved by varying the type and concentration of reducing agent, as well as by adjusting the reaction temperature. This methodology developed for Pd has also been extended to both Au and Pt. As expected for a kinetically controlled product, the anisotropic nanostructure evolved into the thermodynamically favored shape during an aging process.

Royal G. Albridge

Papers

Photoelectron spectroscopy of coordination compounds. II. Palladium complexes

Measured binding energy shifts of "3p" and "3d" electrons in arsenic compounds

Binding energy of the "2p" electrons of silicon in various compounds

.pi.-Bond feedback interpreted from the binding energy of the "2p" electrons of phosphorus

Photoelectron spectroscopy of coordination compounds. Triphenylphosphine and its complexes