Microwave-Assisted Polyol Synthesis of Pt/Pd and Pt/Rh Bimetallic Nanoparticles in Polymer Solutions Prepared by Batch and Continuous-Flow Processing

Abstract

Colloidal dispersions of Pt/Pd and Pt/Rh bimetallic nanoparticles have been synthesized by a microwave-assisted polyol method using ethylene glycol and glycerol as a solvent in the presence of poly­(N-vinyl-2-pyrrolidone) (PVP). The structure of bimetallic nanoparticles has been investigated by means of high-resolution transmission electron microscopy (HRTEM), energy-dispersive X-ray spectroscopy (EDS) elemental mapping, and extended X-ray absorption fine structure (EXAFS). The effectiveness of the batch and continuous-flow processing was demonstrated for the preparation of various bimetallic nanoparticles under multimode or single-mode microwave irradiation. In the single-mode microwave-assisted continuous-flow processing in contrast to the batch processing, the well-dispersed colloidal bimetallic nanoparticles were successfully produced at the boiling temperature of solvent. EXAFS analysis indicated that, in the case of Pt/Pd (1/1) and Pt/Rh (1/1) bimetallic nanoparticles prepared using both batch and continuous-flow processing, the distribution of different metallic species in a particle tended to be a “cluster-in-cluster” structure.

Microwave-Promoted Continuous Flow Systems in Nanoparticle Synthesis—A Perspective

“…TEM images for the Pt/Pd (1/1) NPs and corresponding size distributions in diameter prepared by single-mode MW irradiation in EG through (d) batch-type method and (e) flow-type method. Adapted with permission from Figures 5 and 7 in ref (d and e). Copyright 2018 American Chemical Society.…”

“…This type of nanoparticles consists of two distinct parts named as core and shell. The application of the above-mentioned nanoparticles has the main role to play in choosing the compounds that will be utilized as a shell in these nanomaterials. − In the microwave/flow reactor system, Cong et al reduced salts including H 2 PtCl 6 ·6H 2 O, PdCl 2 , RhCl 3 .3H 2 O by making use of polyol synthesis technique to prepare Pt/Rh and Pt/Pd as core/shell nanostructures in glycerol (Gly.) and ethylene glycol (EG) respectively.…”

Nitrile hydrogenation to secondary amines under ambient conditions over palladium–platinum random alloy nanoparticles

“…Additionally, the Pd K-and Pt L 3 -edge FT EXAFS spectra, which provide information about local coordination structure, depended on how much of the second element was introduced (Figure 3c,d). The split peaks at 2-3 Å in the Pd K-and Pt L 3 -edge spectra were attributed to the heteroatomic Pd-Pt bond, 40,41 which indicates that the PdPt nanoparticles had an alloy structure. In Xray diffraction analysis of PdPt nanoparticles with various metal compositions (Figure S14), diffraction patterns attributed to a facecentered cubic structure were observed for all samples, which is consistent with the results of STEM-EDXS analysis (Figure 2a).…”

Synthesis of cobalt, palladium, and rhenium nanoparticles

“…Similarly, Pd-Ru bimetallic NPs were synthesized by mixing RuCl 3 and K 2 PdCl 4 precursors, adding the reductant solution containing PVP on a monomer basis in triethylene glycol (TEG), and heating the solution at 200 °C in a microflow reactor [151]. Cong et al [152] synthesized Pt-Pd bimetallic NPs through a microwave-assisted polyol technique, in which the mixture of metallic ions and PVP were loaded in a single-mode 300 W microwave apparatus, and then heated to 471 K in EG for about 2-3 min. The same process could be applied in a continuous-flow reactor system for large-scale production.…”