Search

The optical, electronic, and vibrational properties of quaternary CdxZnyOγSδ (CdZnOS) semiconductor nanoparticles grown on mordenite-type zeolite (MOR) were studied using infrared, Raman, photoluminescence in emission and excitation modes, and cathodoluminescence spectroscopy. Semiconductor–mordenite (CdZnOS-MOR) composites were prepared utilizing low-cost and scalable methods: 1) Ion-exchange with as-synthesized sodium-mordenite and 2) a one-pot direct synthesis of zinc/cadmium-mordenite using a modified sol–gel technique, which were followed by sulfidation under a flow of H2S. The results of our vibrational studies have revealed the characteristic signals for the zinc-blende-type phase of the quaternary nanoparticles. From our photoluminescence analysis, the CdZnOS-MOR nanocomposites exhibits an up-conversion phenomenon, which is strongly related to the quantum confinement effect, while a high energy cathodoluminescence response established that the diversity of the transitions in this up-conversion process is associated to the wide distribution of size and stoichiometry of the nanoparticles. The luminescent, photoluminescent, and cathodoluminescent properties make the nanocomposite a promising photoactive material for application in photocatalysis.

Photocatalysts based on silver or gold metallic and CdS semiconductor nanoparticles embedded on a mordenite matrix (M-CdS/MOR), was successfully synthesized and tested to obtain glucuronic acid by photoconversion of glucose. The M-CdS/MOR photocatalyst exhibited a synergistic interaction between the plasmonic behavior from metallic nanoparticles and the photoactive properties of semiconductor nanoparticles, which leads to the photoconversion of the glucose (38% in 60 min). The reaction mechanisms are presented and discussed.

A highly efficient photocatalyst based on Ag-metal and CdZnSO-semiconductor nanoparticles, grown on a zeolitic matrix, was successfully synthesized by a solvent- and template-free procedure, and tested on the photodegradation of recalcitrant disperse orange 30 dye. The Ag-CdZnSO/ZM nanocomposite showed great synergistic interaction between the surface plasmon resonance of the Ag nanoparticles, the photoactive properties of CdZnSO nanoparticles, and the catalytic properties of the zeolitic, which leads to the degradation of the dye (99.5% in 90 min, from optical absorbance). The reaction mechanisms are presented and discussed. Also, the small amount of acetone required as sensitizer was eliminated during the process.

Atomic, electronic, and compositional structure of quaternary CdxZnySδOγ semiconductor nanoparticles grown on synthesized mordenite-type zeolite (MOR) is discussed in this work. Semiconductor–MOR composites were synthesized using two different methods: by Cd2+-Zn2+-ion exchange with synthesized sodium-mordenite, and by direct synthesis of zinc/cadmium-mordenite through a variant of the sol–gel technique, both followed by sulfidation treatment in H2S flow. We show that CdxZnySδOγ semiconductor nanoparticles grow strongly bonded, revealing a core–shell-type arrangement with a wide-open (a = 8.33 A) cubic fcc structure, and constrained by the MOR surface structure. Because of the core–shell-type nanoparticles and their observed structural and optical properties, these photoactive composites are promising candidates for applications in the fields of photocatalysis and optoelectronics.

"Successful synthesis of metal–, semiconductor–, and metal/semiconductor–mordenite nanocomposites, using geothermal solid waste as precursor is reported. Powders of nanostructured composites, consisting of metal and/or semiconductor nanoparticles grown on a mordenite-type zeolitic matrix surface, were synthesized by a one-step solvent-free and organic template-free process. The developed methodology is capable of controlling and tuning the final properties of composites from their synthesis and is also reproducible and repeatable. For comparison and demonstration of the application of the final products, dye photocatalysis degradation tests were done using commercial TiO 2 as reference (degradation reached ∼ 75% in 215 min, k = 0.004 min − 1 ), [M]–S–MOR samples revealed better performance ( ≥ 95% in 100 min, k = 0.009 min − 1 ). All Rights Reserved © 2016 Universidad Nacional Autónoma de México, Centro de Ciencias Aplicadas y Desarrollo Tecnológico. This is an open access item distributed under the Creative Commons CC License BY-NC-ND 4.0."

The antimicrobial activity of silver nanoparticles (AgNPs) is currently used as an alternative disinfectant with diverse applications, ranging from decontamination of aquatic environments to disinfection of medical devices and instrumentation. However, incorporation of AgNPs to the environment causes collateral damage that should be avoided. In this work, a novel Ag-based nanocomposite (CEOBACTER) was successfully synthetized. It showed excellent antimicrobial properties without the spread of AgNPs into the environment. The complete CEOBACTER antimicrobial characterization protocol is presented herein. It is straightforward and reproducible and could be considered for the systematic characterization of antimicrobial nanomaterials. CEOBACTER showed minimal bactericidal concentration of 3 μg/ml, bactericidal action time of 2 hours and re-use capacity of at least five times against E. coli cultures. The bactericidal mechanism is the release of Ag ions. CEOBACTER displays potent bactericidal properties, long lifetime, high stability and re-use capacity, and it does not dissolve in the solution. These characteristics point to its potential use as a bactericidal agent for decontamination of aqueous environments.