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Author: Verónica Savignano
Lives & Webinars Program: first month.
During the month of June, five technical webinars were held on the Zoom platform, with live transmission via B-MRS’s Facebook platform, within the Live & Webinars program, organized by B-MRS in partnership with instrumentation companies.
By the end of August, 12 more webinars will be offered. The program includes a variety of subjects, from fundamentals and applications of techniques widely used by the Materials research community, to the presentation of state-of-the-art research instruments and digital tools for teaching in the field of Materials.
The already held online seminars had audiences of up to 500 participants. “We are happy to see that many people, especially young people, are using this pandemic time to gain knowledge and for self-improvement,” says Professor Mônica Cotta, president of B-MRS, who has participated in all the seminars.
Programming, information and registration (free): https://www.sbpmat.org.br/en/lives-webinars/
Watch the past webinars recordings:
- “Micro-XRF aplicado a Ciências dos Materiais” (Essencis and Bruker). See here.
- “Microscopias FTIR, Raman e Eletrônica de Transmissão para Análise de Materiais” (Thermo Fisher). See here.
- “Técnicas de magnetometria para a pesquisa em nanopartículas magnéticas” (Quantum Design). See here.
- “3D optical profilometry for material science applications” (Sensofar and Analítica). See here.
- “Crossbeam laser – Enabling New Microscopy Workflows Through Gentle Large-Volume Material Removal” (Zeiss). See here.
Featured paper: Nanocontainers for intelligent anticorrosion coatings.
Traditional coatings are often effective in protecting steel structures from corrosion by providing a physical barrier that prevents contact between the substrate and corrosive elements. However, when wear generates cracks or pores in these coatings, the substrates are exposed and eventually corrode.
A scientific team from the Brazilian Federal University of Paraná (UFPR) developed a nanotechnology-based coating that offers active protection against corrosion. When the coating shows a flaw, exposing the substrate to corrosive elements, two anti-corrosion mechanisms are activated without human intervention. The coating has very special additives to carry out this intelligent procedure: nanocontainers capable of storing a compound that inhibits corrosion (molybdate) and release it, on demand, in the presence of corrosive elements.
UFPR’s nanocontainers are structures of nanometric dimensions that appear in the form of overlapping two-dimensional sheets (lamellae), separated by a space of a few angstroms. It is in this interlamellar space that molybdate is stored. When a nanoreservoir comes into contact with corrosive environments, such as the sodium chloride (NaCl) solution used in the UFPR experiments, a negative ion exchange reaction occurs: molybdate anions leave the interlamellar space and chloride anions occupy these spaces. In this exchange, the molybdate is free to form a protective film on the exposed substrate surface, while the corrosive anions are “trapped” in the nanoreservoir.
“The main contribution of the work is related to the active corrosion protection of steel. While traditional coatings provide only barrier protection, that is, passive protection, the intelligent coating developed in this work promotes active protection, releasing the molybdate corrosion inhibitor from the lamellar nanoreservoir on demand, through an anion exchange mechanism,” summarizes Débora Abrantes Nunes Leal, doctoral student of the Graduate Program in Materials Engineering and Science at UFPR and corresponding author of the article reporting the research, recently published in ACS Applied Materials & Interfaces. “In addition to releasing the inhibitor in a controlled manner, the lamellar nanoreservoir also “captures” the chloride anions, acting as a trap for these species and, therefore, also contributes to reducing the corrosive environment,” concludes the doctoral student.
Industrial scale use
Produced by means of a quick and simple process and using low-cost, abundant raw materials with low environmental impacts, such as zinc, UFPR’s nanocontainers have the potential for large-scale manufacturing process. When used as coatings additives, as in the UFPR research, nanocontainers could increase the useful life of steel structures found in atmospheres with high concentrations of corrosive compounds, such as, for example, marine atmospheres or close to chemical plants.
According to Débora, there is already a market, mainly in Europe, still incipient, of intelligent coatings to combat corrosion for the aeronautical and petrochemical industries. However, these coatings use as reservoirs of anticorrosive compounds, mainly polymeric microcapsules or double lamellar hydroxides, which are more complex to manufacture, costly and have a greater environmental impact than the lamellar hydroxyses used in UFPR’s nanocontainers . According to the authors of the article, these materials had never been used to store and release corrosion inhibitors before this work, neither in industry nor in the scientific literature.
All the work reported in the article of ACS Applied Materials and Interfaces was carried out by Débora Abrantes Nunes Leal within her still-in-progress doctoral thesis, which started in 2017. The research is guided by Professor Cláudia Marino (advisor), who is an expert in corrosion and protection of materials, and by Professor Fernando Wypych (co-advisor), whose expertise is the synthesis and characterization of lamellar materials. The work received funding from the Brazilian agencies Capes, CNPq and Finep.
Currently, the research on nanocontainers continues, and the authors indicate that they will soon present new results, including those related to the use of other corrosion inhibitors.
[Paper: Zinc-Layered Hydroxide Salt Intercalated with Molybdate Anions as a New Smart Nanocontainer for Active Corrosion Protection of Carbon Steel. Débora Abrantes Leal, Fernando Wypych, and Cláudia Eliana Bruno Marino. ACS Appl. Mater. Interfaces 2020, 12, 17, 19823–19833. https://doi.org/10.1021/acsami.0c02378.]
(Português) Processo seletivo para mestrado e doutorado em Física no PPGF/UFRN.
Sorry, this entry is only available in Brazilian Portuguese.
B-MRS Newsletter. Year 7, issue 5.
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(Português) Inscrições para mestrado e doutorado em Materiais e Nanotecnologia na PUC-Rio.
Sorry, this entry is only available in Brazilian Portuguese.
(Português) Processo seletivo para mestrado em Física de Materiais na UFOP.
Sorry, this entry is only available in Brazilian Portuguese.
(Português) Processo seletivo para mestrado e doutorado em Materiais na UNESP – Ilha Solteira.
Sorry, this entry is only available in Brazilian Portuguese.
Featured paper: Catalyzing hydrogen production.
[Paper: NiMo–NiCu Inexpensive Composite with High Activity for Hydrogen Evolution Reaction. Hugo L. S. Santos, Patricia G. Corradini, Marina Medina, Jeferson A. Dias, and Lucia H. Mascaro. ACS Appl. Mater. Interfaces. 2020, 12, 15, 17492–17501. https://doi.org/10.1021/acsami.0c00262]
Hydrogen, whose combustion does not generate polluting emissions, is currently recognized as the most promising alternative to fossil fuels. However, there are still challenges in the sustainable production of this fuel, such as the development of a production process that is at the same time clean, economical and efficient.
Water electrolysis is one of the processes that can fit in these conditions. As the name implies, the process consists of the division of the water molecule, based on the action of an electric current. As a result, this simple reaction produces hydrogen gas and oxygen gas. However, to become a viable industrial process, water electrolysis needs catalysts that accelerate hydrogen production without significantly increasing its costs.
A work by a scientific team from the Brazilian Federal University of São Carlos (UFSCar), recently reported in an article in ACS Applied Materials & Interfaces, brings a contribution to overcome this challenge. “The main contribution of our work is to obtain a catalyst with significant performance improvement for the production of hydrogen from water electrolysis,” summarizes Lucia Helena Mascaro, professor at UFSCar and corresponding author of the paper.
The new catalyst is a film that can be deposited on the surface of the electrode used in the electrolysis process, which is why it is called an electrocatalyst. The electron transfer occurs in this negatively charged electrode, which causes hydrogen to detach from the water molecule.
While some electrocatalysts are made with noble metals, such as platinum, the Brazilian team looked for a material based on more abundant and economical elements, but which had good electrocatalytic activity and durability. The final option was for a metallic alloy composed of nickel (Ni), molybdenum (Mo) and copper (Cu), which presented two defined regions (phases), NiMo and NiCu, both with crystalline structures, composing a composite material.
“The NiMo-NiCu material showed excellent electrocatalytic activity, robustness, low toxicity, wide availability and economic viability for the hydrogen release reaction, called hydrogen evolution reaction. This material was easily obtained by electroplating, which is a simple, inexpensive and scalable technique, on a carbon steel substrate, without the need for any other treatment,” says Mascaro.
The main secret of the good performance of the film as an electrocatalyst is dependent on surface roughness, caused by the presence of copper. In relative terms, the NiMo-NiCua film presented roughness more than thirty times greater than the NiMo film, which is widely used to catalyze the release of hydrogen in water electrolysis.
In fact, the topography of a rough surface provides many more opportunities for the water molecule to come in contact with the catalyst and then the electron transfer that generates hydrogen release occurs. “The increase in the film’s roughness implies the formation of a greater amount of hydrogen for the same geometric area of the catalyst,” explains Professor Mascaro. “In addition, the NiMo-NiCu composite showed high stability during prolonged electrolysis,” she adds.
In search of the most suitable material
The genesis of the research dates back to 2012, when Professor Lucia Helena Mascaro and her team from at the Interdisciplinary Laboratory of Electrochemistry and Ceramics (LIEC) set out to find a material that would improve the efficiency of hydrogen production by water hydrolysis, and that could be produced through electrodeposition – a fast and viable process at an industrial scale, in which Professor Mascaro and her group have extensive expertise.
After developing some coatings with nickel and iron alloys, and making a thorough review of the scientific literature, the group came to the conclusion that a nickel, molybdenum and copper (Ni-Mo-Cu) alloy would be promising in terms of electrocatalytic activity and robustness, says the scientist. The UFSCar team then decided to add copper to the Ni-Mo alloy.
After defining the material, the team immersed in studying the conditions of the electroplating process. In fact, a key point for electrodeposition to generate the expected results is to correctly define the composition of the solution in which the process occurs. In this solution, also known as “electrodeposition bath,” the metals that will be deposited in the form of salts are found.
Thus, the team produced films with different concentrations of copper, characterized all of them and verified the performance of each one as an electrocatalyst in the release of hydrogen. At the end of the study, the researchers were able to safely determine which of the “recipe” had been the most successful.
The work was mainly carried out within Hugo Leandro Sousa Dos Santos’s master’s dissertation, supervised by Professor Mascaro and defended in 2018 in the Graduate Program in Chemistry at UFSCar. The research was funded by FAPESP, including through the Functional Materials Development Center (CMDF), CAPES and CNPq, and involved two UFSCar laboratories, LIEC and the Laboratory of Synthesis and Formulation Ceramic (LaFSCer), of the Materials Engineering Department.
(Português) Novos University Chapters da SBPMat na UFPR e UFCAT.
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