Solvent-Adoptable Polymer Ni/NiCo Alloy Nanochains: Highly Active and Versatile Catalysts for Various Organic Reactions in both Aqueous and Nonaqueous Media

Abstract

The synthesis of solvent-adoptable monometallic Ni and NiCo alloy nanochains by a one-pot solution phase reduction method in the presence of poly(4-vinylphenol) (PVPh) is demonstrated. The elemental compositions of the as-prepared alloys are determined by inductively coupled plasma optical emission spectroscopy (ICP-OES) and energy-dispersive X-ray spectroscopy (EDS), which are matching well with the target compositions. The morphology analysis by TEM and FESEM confirms that the nanochains are made up of organized spherical monometallic Ni or bimetallic NiCo alloy nanoparticles (NPs). However, there is no nanochain formation when the alloy is prepared without the polymer PVPh. A possible mechanism for the formation of such NiCo alloy nanochains is discussed. The X-ray diffraction and selected area electron diffraction patterns reveal that the Ni/NiCo alloys are polycrystalline with fcc structure. The obtained Ni or NiCo alloy nanostructures are ferromagnetic with very high coercivity. The polymer Ni/NiCo alloy nanochains are dispersible in both water and organic media that makes them versatile enough to use as catalysts in the reactions carried out in both types of media. The catalytic activities of these Ni/NiCo alloy nanochains are extremely high in the borohydride reduction of p-nitrophenol in water. In organic solvents, these nanochains can act as efficient catalysts, under ligand-free condition, for the C-S cross-coupling reactions of various aryl iodides and aryl thiols for obtaining the corresponding cross-coupled products in good to excellent yield up to 96%. The NiCo nanochain also successfully catalyzes the C-O cross-coupling reaction in organic medium. A possible mechanism for NiCo alloy nanochain-catalyzed cross-coupling reaction is proposed.

Ni–Co alloy nanostructures anchored on mesoporous silica nanoparticles for non-enzymatic glucose sensor applications

“…3b) exhibited the characteristic diffraction peaks at 45.96 , 51.18 and 76.50 which are ascribed to the (111), (200) and (220) planes of the face centred crystalline cubic (fcc) structure, respectively. 44,45 The crystallite sizes of Ni and the Ni-Co nanoparticles in MSN/Ni and MSN/ Ni-Co composite, respectively, were calculated from the (111) reection plane and were found to be 5 nm using Scherrer's formula; these ndings are identical to the observed TEM images. 3c), which resemble the lattice parameters of both Co (3.544Å) and Ni (3.523Å) (JCDPS 15-0806, Co; 04-0850, Ni).…”

FACILE AND LARGE-SCALE FABRICATION OF Ni NANOCHAINS BY A CHEMICAL REDUCTION METHOD WITH THE ASSISTANCE OF EXTERNAL MAGNETIC FIELD

“…It is worth noting that the yields of the products can reach above 96%. Compared with the wet chemical method to prepare Ni nanochains reported recently, 17,18,21 in which a large amount of organic solvent and surfactant is required, our approach presented here is facile and cost e®ective, which is very suitable for large-scale production of these chain-like nanostructures. Figure 1(b) indicates these nanochains are composed of Ni nanoparticles with an average diameter of about 140 nm, which array along almost the same direction.…”

PtNi nanoparticles embedded in porous silica microspheres as highly active catalysts for p-nitrophenol hydrogenation to p-aminophenol

“…The improvement of catalytic activities can be attributed to electronic effect (downshift of the dband center on PtNi alloy) and geometric effect (the unique structures of PtNi alloys), which can facilitate the relaying of electrons to p-nitrophenol from borohydride ions and endow more activity sites available for the adsorption of reactant molecules. 9,49,50 In addition, PtNi embedded into the surface of mesoporous microspheres, which can expose nanocatalysts directly to the reactants and increase its catalytic efficiency correspondingly.…”