E. Chavira

Synthesis by Microwaves of Bimetallic Nano-Rhodium-Palladium

An improved acrylamide sol-gel technique using a microwave oven in order to synthesize bimetallic Rh-Pd particles is reported and discussed. The synthesis of Pd and Rh nanoparticles was carried out separately. The polymerization to form the gel of both Rh and Pd was carried out at 80°C under constant agitations. The method chosen to prepare the Rh and Pd xerogels involved the decomposition of both gels. The process begins by steadily increasing the temperature of the gel inside a microwave oven (from 80°C to 170°C). In order to eliminate the by-products generated during the sol-gel reaction, a heat treatment at a temperature of 1000°C for 2 h in inert atmosphere was carried out. After the heat treatment, the particle size increased from 50 nm to 200 nm, producing the bimetallic Rh-Pd clusters. It can be concluded that the reported microwave-assisted, sol-gel method was able to obtain nano-bimetallic Rh-Pd particles with an average size of 75 nm.

Nanostructure Obtained by Sol-gel Acrylamide Polymerization in Y-V-O System

The Y-V-O system was prepared by sol-gel acrylamide polymerization. Y2O3 and V2O5 were separately dissolved in HNO3 with distilled water. Ethylenediamine-tetraacetic acid was used as a chelating agent to isolate Y and V cations. Then, the two solutions were mixed and NH4OH was used to adjust the pH to 3.4. To this solution we added acrylamide, C7H10N2, and a chemical initiator C8H18N6·2HCl at 80C to accomplish the polymerization. This process took 8 min. The obtained gel was dried at 200C for 12h; it results in a porous foam material (xerogel).

Synthesis of rhodium nano-particles by sol-gel processing

M. Ugalde, E. Chavira, M. T. Ochoa-Lara, C. Quintanar, F. Espinosa-Magaña, R. Lopez-Juárez, A. Tejeda, C. Flores, I. A. Figueroa 1. Centro de Investigación en Materiales Avanzados, S.C., Laboratorio Nacional de Nanotecnología, Ave. Miguel de Cervantes #120, C.P. 31109, Chihuahua, Chih., MÉXICO 2. Instituto de Investigaciones en Materiales, Universidad Nacional Autónoma de México, A. P. 70-360, 04510 México, D. F., MÉXICO 3. Facultad de Ciencias, Universidad 3000 Circuito Exterior S/N, C.P. 04510 Ciudad Universitaria, MÉXICO.