Organic Transformations on Metal Nanoparticles: Controlling Activity, Stability, and Recyclability by Support and Solvent Interactions

Abstract

The different mechanisms by which the support and the solvent can influence the catalytic properties of a metal nanoparticle (NP) are reviewed. The use of a support not only significantly facilitates the recycling of NPs but also has many additional advantages varying from enhanced stabilization of the NP dispersion to the alteration of the electronic properties of the metal, shape selectivity effects, and even active participation in the reaction mechanism. The correct choice of solvent, on the other hand, can drastically influence properties such as the morphology of the particles and, in the case of alloys, determine the composition of the NPs. Judicious solvent selection also enhances recyclability and stability, and in some cases, the solvent plays a cocatalytic role. Despite the many beneficial effects of combining metal NPs with the correct support or solvent, many processes are not well understood. Further research should be conducted on elucidating the general mechanisms behind the support-NP or solvent-NP interactions.

Glycerol as Suitable Solvent for the Synthesis of Metallic Species and Catalysis

“…In the case of the synthesis of MNPs under “wet” conditions,48 the solvent plays a non‐innocent role with regard to the intrinsic structure and as well as to self‐organisations of MNPs in the liquid phase. However few systematic studies have been reported on the interactions between nanoparticles and solvents 49. As well‐established, nanometric objects tend to agglomerate in the absence of agents providing electrostatic, steric, and/or ligand coordination support, because small particles represent mostly non‐equilibrium systems 50.…”

Metal–Organic Framework Supported Palladium Nanoparticles: Applications and Mechanisms

“…Unfortunately, Pd NPs have high surface energy and surface‐to‐volume ratio, so they are thermally unstable, tend to aggregate, and/or convert into different nanocrystal structures under the reaction/pretreatment process, resulting in the deterioration of the reactivity. Consequently, how to control the morphology, size, and dispersion of Pd NPs is the key factor in obtaining high and stable activity . To achieve this purpose, various porous materials such as zeolites, meso‐porous aluminosilicates, activated carbon (AC), silica, and metal–organic frameworks (MOFs) have been explored as the supporter to acquire small and stable Pd NPs with particular shapes .…”

Active hydrogenation Rh nanocatalysts protected by new self-assembled supramolecular complexes of cyclodextrins and surfactants in water

“…[4][5] Recently, nanometer-sized metallic particles have been developed as relevant catalysts for performing green organic transformation processes because of their outstanding intrinsic properties, combining the advantages of homogeneous and heterogeneous catalysts. [6][7][8][9] Besides their pertinent activities owing to a high number of surface-exposed metal atoms and their original selectivities regarding to their unique surface structures and combined they could also provide improved recovery potentialities, which constitute sine qua non conditions for eco-responsible applications. 11 Thus, the use of colloidal metallic particles finely dispersed in water constitutes one of the most effective and sustainable approaches to achieve the targeted recycling objective, through a biphasic water-substrate catalytic process.…”