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Nanotechnology in Americas

A special issue of Molecules (ISSN 1420-3049). This special issue belongs to the section "Nanochemistry".

Deadline for manuscript submissions: closed (31 December 2023) | Viewed by 8225

Special Issue Editors


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Guest Editor
Colegio de Ciencias e Ingenerias, Universidad of San Francisco de Quito, Quito 107910, Ecuador
Interests: remediation; safety; target; sensing
Special Issues, Collections and Topics in MDPI journals

Special Issue Information

Dear Colleagues,

Nanotechnology includes the control of matter at the nanoscale, where unique phenomena and unusual properties enable novel applications. Nanotechnology applications are very broad, such as textile, renewable energy, biomedical, healthcare, environment, electronics, optics, agriculture, food science, manufacturing, and industrial. Nanoprocessing, nanofabrication, and nanomaterials have been key to enabling the development of nanotechnologies. These nanomaterials have unique properties due to their size, and are composed of organic and inorganic materials from natural or synthetic sources. As nanotechnology efforts continue to evolve, their geographical polarization becomes broader. For this reason, this Special Issue is dedicated to the current status of nanotechnology in the Americas, including all the different efforts in specific areas. The objective is to highlight and acknowledge the advances and challenges in the region of the Americas. Original research articles, reviews, or communications within the scope of nanotechnology and from researchers based at any university or scientific institution in the Americas are welcome. 

Prof. Dr. Frank Alexis
Dr. Si Amar Dahoumane
Guest Editors

Manuscript Submission Information

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Keywords

  • nanoscience
  • nanotechnology
  • nanomaterials
  • nanoprocessing
  • nanofabrication

Published Papers (4 papers)

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Research

15 pages, 5694 KiB  
Article
Hydrothermal Synthesis of Bismuth Ferrite Hollow Spheres with Enhanced Visible-Light Photocatalytic Activity
by Thomas Cadenbach, Valeria Sanchez, Daniela Chiquito Ríos, Alexis Debut, Karla Vizuete and Maria J. Benitez
Molecules 2023, 28(13), 5079; https://0-doi-org.brum.beds.ac.uk/10.3390/molecules28135079 - 29 Jun 2023
Viewed by 1229
Abstract
In recent years, semiconductor hollow spheres have gained much attention due to their unique combination of morphological, chemical, and physico-chemical properties. In this work, we report for the first time the synthesis of BiFeO3 hollow spheres by a facile hydrothermal treatment method. [...] Read more.
In recent years, semiconductor hollow spheres have gained much attention due to their unique combination of morphological, chemical, and physico-chemical properties. In this work, we report for the first time the synthesis of BiFeO3 hollow spheres by a facile hydrothermal treatment method. The mechanism of formation of pure phase BiFeO3 hollow spheres is investigated systematically by variation of synthetic parameters such as temperature and time, ratio and amount of precursors, pressure, and calcination procedures. The samples were characterized by X-ray powder diffraction, scanning electron microscopy, energy dispersive X-ray spectroscopy, and UV-vis diffuse reflectance spectroscopy. We observe that the purity and morphology of the synthesized materials are very sensitive to synthesis parameters. In general, the chemically and morphologically very robust hollow spheres have diameters in the range of 200 nm to 2 μm and a wall thickness of 50–200 nm. The synthesized BiFeO3 hollow spheres were applied as catalysts in the photodegradation of the model pollutant Rhodamine B under visible-light irradiation. Notably, the photocatalyst demonstrated exceptionally high removal efficiencies leading to complete degradation of the dye in less than 150 min at neutral pH. The superior efficiencies of the synthesized material are attributed to the unique features of hollow spheres. The active species in the photocatalytic process have been identified by trapping experiments. Full article
(This article belongs to the Special Issue Nanotechnology in Americas)
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19 pages, 6848 KiB  
Article
One-Pot Graphene Supported Pt3Cu Nanoparticles—From Theory towards an Effective Molecular Oxygen Reduction Reaction Catalyst
by Carlos Daniel Galindo-Uribe, Gerald Geudtner, Patrizia Calaminici and Omar Solorza-Feria
Molecules 2023, 28(13), 5072; https://0-doi-org.brum.beds.ac.uk/10.3390/molecules28135072 - 28 Jun 2023
Viewed by 1196
Abstract
In this work, recent research progresses in the formation of Pt3Cu nanoparticles onto the surface of graphene are described, and the obtained results are contrasted with previously published theoretical studies. To form these nanoparticles, tetrabutylammonium hexachloroplatinate, and copper acetylacetonate are used [...] Read more.
In this work, recent research progresses in the formation of Pt3Cu nanoparticles onto the surface of graphene are described, and the obtained results are contrasted with previously published theoretical studies. To form these nanoparticles, tetrabutylammonium hexachloroplatinate, and copper acetylacetonate are used as platinum and copper precursors, respectively. Oleylamine is used as a reductor and a solvent. The obtained catalyst is characterized via X-ray diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscopy (SEM), and energy dispersive spectroscopy X-ray (EDS). To assess the catalytic activity, the graphene-supported Pt3Cu material is tested with cyclic voltammetry, “CO stripping”, and oxygen reduction reaction potentiodynamic curves to find the nature and the intrinsic electrochemical activity of the material. It can be observed that the tetrabutylammonium cation plays a critical role in anchoring and supporting nanoparticles over graphene, from which a broad discussion about the true nature of the anchoring mechanism was derived. The growth mechanism of the nanoparticles on the surface of graphene was observed, supporting the conducted theoretical models. With this study, a reliable, versatile, and efficient synthesis of nanocatalysts is presented, demonstrating the potentiality of Pt3Cu/graphene as an effective cathode catalyst. This study demonstrates the importance of reliable ab inito theoretical results as a useful source of information for the synthesis of the Pt3Cu alloy system. Full article
(This article belongs to the Special Issue Nanotechnology in Americas)
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16 pages, 2500 KiB  
Article
Endo-Exoglucanase Synergism for Cellulose Nanofibril Production Assessment and Characterization
by Ricardo Gonzalo Ramírez Brenes, Lívia da Silva Chaves, Ninoska Bojorge and Nei Pereira, Jr.
Molecules 2023, 28(3), 948; https://0-doi-org.brum.beds.ac.uk/10.3390/molecules28030948 - 18 Jan 2023
Viewed by 1779
Abstract
A study to produce cellulose nanofibrils (CNF) from kraft cellulose pulp was conducted using a centroid simplex mixture design. The enzyme blend contains 69% endoglucanase and 31% exoglucanase. The central composite rotational design (CCRD) optimized the CNF production process by achieving a higher [...] Read more.
A study to produce cellulose nanofibrils (CNF) from kraft cellulose pulp was conducted using a centroid simplex mixture design. The enzyme blend contains 69% endoglucanase and 31% exoglucanase. The central composite rotational design (CCRD) optimized the CNF production process by achieving a higher crystallinity index. It thus corresponded to a solid loading of 15 g/L and an enzyme loading of 0.974. Using the Segal formula, the crystallinity index (CrI) of the CNF was determined by X-ray diffraction to be 80.87%. The average diameter of the CNF prepared by enzymatic hydrolysis was 550–600 nm, while the one produced by enzymatic hydrolysis and with ultrasonic dispersion was 250–300 nm. Finally, synergistic interactions between the enzymes involved in nanocellulose production were demonstrated, with Colby factor values greater than one. Full article
(This article belongs to the Special Issue Nanotechnology in Americas)
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21 pages, 4501 KiB  
Article
Functionalization and Evaluation of Inorganic Adsorbents for the Removal of Cadmium in Wastewater
by Ana Lucía Campaña, Amaimen Guillén, Ricardo Rivas, Veronica Akle, Juan C. Cruz and Johann F. Osma
Molecules 2021, 26(14), 4150; https://0-doi-org.brum.beds.ac.uk/10.3390/molecules26144150 - 08 Jul 2021
Cited by 6 | Viewed by 2847
Abstract
This study presents the feasibility of using various functionalized substrates, Fe3O4 nanoparticles (NPs) and Al2O3 spheres, for the removal of Cd from aqueous solution. To improve the materials’ affinity to Cd, we explored four different surface modifications, [...] Read more.
This study presents the feasibility of using various functionalized substrates, Fe3O4 nanoparticles (NPs) and Al2O3 spheres, for the removal of Cd from aqueous solution. To improve the materials’ affinity to Cd, we explored four different surface modifications, namely (3-Aminopropyl) triethoxysilane (APTES), L-Cysteine (Cys) and 3-(triethoxysilyl) propylsuccinic anhydride (CAS). Particles were characterized by FTIR, FIB-SEM and DLS and studied for their ability to remove metal ions. Modified NPs with APTES proved to be effective for Cd removal with efficiencies of up to 94%, and retention ratios up to 0.49 mg of Cd per g of NPs. Batch adsorption experiments investigated the influence of pH, contact time, and adsorbent dose on Cd adsorption. Additionally, the recyclability of the adsorbent and its potential phytotoxicity and animal toxicity effects were explored. The Langmuir, Freundlich, pseudo-first-order and pseudo-second-order models were applied to describe the behavior of the Cd adsorption processes. The adsorption and desorption results showed that Fe3O4 NPs modified with APTES are promising low-cost platforms with low phytotoxicity for highly efficient heavy metal removal in wastewater. Full article
(This article belongs to the Special Issue Nanotechnology in Americas)
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