On Metal Segregation of Bimetallic Nanocatalysts Prepared by a One-Pot Method in Microemulsions

• Published in: Catalysts 2017-02, Vol.7 (12), p.68
• Main Authors: Tojo, Concha, Buceta, David, López-Quintela, Manuel
• Format: Article
• Language: English
• Subjects: bimetallic nanoparticles; Catalysts; Chemical reactions; microemulsion; nanocatalysts; one-pot method; simulation
• ISSN: 2073-4344; 2073-4344
• DOI: 10.3390/catal7020068

A comparative study on different bimetallic nanocatalysts prepared from microemulsions using a one-pot method has been carried out. The analysis of experimental observations, complemented by simulation studies, provides detailed insight into the factors affecting nanoparticle architecture: (1) The metal segregation in a bimetallic nanocatalysts is the result of the combination of three main kinetic parameters: the reduction rate of metal precursors (related to reduction standard potentials), the material intermicellar exchange rate (determined by microemulsion composition), and the metal precursors concentration; (2) A minimum difference between the reduction standard potentials of the two metals of 0.20 V is needed to obtain a core-shell structure. For values Δε0 smaller than 0.20 V the obtaining of alloys cannot be avoided, neither by changing the microemulsion nor by increasing metal concentration; (3) As a rule, the higher the film flexibility around the micelles, the higher the degree of mixture in the nanocatalyst; (4) A minimum concentration of metal precursors is required to get a core-shell structure. This minimum concentration depends on the microemulsion flexibility and on the difference in reduction rates.