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2. Trends on 3d Transition Metal Coordination on Monolayer MoS$_2$

Author

Liu, He, Silva, Walner Costa, de Souza, Leonardo Santana Gonçalves, Veiga, Amanda Garcez, Seixas, Leandro, Fujisawa, Kazunori, Kahn, Ethan, Zhang, Tianyi, Zhang, Fu, Yu, Zhuohang, Thompson, Katherine, Lei, Yu, de Matos, Christiano J. S., Rocco, Maria Luiza M., Terrones, Mauricio, and Grasseschi, Daniel

Subjects
Condensed Matter - Materials Science, Physics - Applied Physics
Abstract

Two-dimensional materials (2DM) have attracted much interest due to their distinct optical, electronic, and catalytic properties. These properties can be by tuned a range of methods including substitutional doping or, as recently demonstrated, by surface functionalization with single atoms, increasing even further 2DM portfolio. Here we theoretically and experimentally describe the coordination reaction between MoS$_2$ monolayers with 3d transition metals (TMs), exploring the nature and the trend of MoS$_2$-TMs interaction. Density Functional Theory calculations, X-Ray Photoelectron Spectroscopy (XPS), and Photoluminescence (PL) point to the formation of MoS$_2$-TM coordination complexes, where the adsorption energy trend for 3d TM resembles the crystal-field (CF) stabilization energy for weak-field complexes. Pearson's theory for hard-soft acid-base and Ligand-field theory were applied to discuss the periodic trends on 3d TM coordination on the MoS$_2$ surface. We found that softer acids with higher ligand field stabilization energy, such as Ni$^{2+}$, tend to form bonds with more covalent character with MoS$_2$, which can be considered a soft base. On the other hand, harder acids, such as Cr$^{3+}$, tend to form bonds with more ionic character. Additionally, we studied the trends in charge transfer and doping observed in the XPS and PL results, where metals such as Ni led to an n-type of doping, while Cu functionalization results in p-type doping. Therefore, the formation of coordination complexes on TMD's surface is demonstrated to be a promising and effective way to control and to understand the nature of the single-atom functionalization of TMD., Comment: 27 pages, 8 figures, Support Information after references section

Published
2021

5. Structural, optical and catalytic properties of ZnO-SiO2 colored powders with the visible light-driven activity

Author

Nazarkovsky, Michael, Czech, Bożena, Żmudka, Alicja, Bogatyrov, Viktor M., Artiushenko, Olena, Zaitsev, Vladimir, Saint-Pierre, Tatiana D., Rocha, Rafael C., Kai, Jiang, Xing, Yutao, Gonçalves, Wellington D.G., Veiga, Amanda G., Rocco, Maria Luiza M., Safeer, Syed Hamza, Galaburda, Mariia V., Carozo, Victor, Aucélio, Ricardo Q., Caraballo-Vivas, Richard J., Oranska, Olena I., and Dupont, Jairton

Published
2021
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6. Inducing molecular orientation in solution-processed thin films of fluorene-bithiophene-based copolymer : thermal annealing vs. solvent additive

Author

Pereira, Cassia Ferreira Coutinho, Borges, Bruno G. A. L., Sousa, Karlison R. A., Holakoei, Soheila, Roman, Lucimara S., Araujo, Moyses, Cremona, Marco, Koehler, Marlus, Marchiori, Cleber, Rocco, Maria Luiza M., Pereira, Cassia Ferreira Coutinho, Borges, Bruno G. A. L., Sousa, Karlison R. A., Holakoei, Soheila, Roman, Lucimara S., Araujo, Moyses, Cremona, Marco, Koehler, Marlus, Marchiori, Cleber, and Rocco, Maria Luiza M.

Abstract

A deep understanding of the factors influencing the morphology of thin films based on conjugated polymers is essential to boost their performance in optoelectronic devices. Herein, we investigated the electronic structure and morphology of thin films of the copolymer poly(9,9-dioctyl-fluorenyl-co-bithiophene) (F8T2) in its pristine form as well as samples processed with the solvent additive 1,8-diiodooctane (DIO) or post-processed through thermal annealing treatment. Measurements were carried out using angle-resolved S K-edge NEXAFS (near-edge X-ray absorption fine structure) in total electron yield (TEY) and fluorescence yield (FY) detection modes. Two main transitions were observed at the S 1s NEXAFS spectra: S 1s -> pi* and S 1s -> sigma* (S-C). The observed dichroism pointed to a face-on orientation of the conjugated backbone, which was significantly increased for F8T2 films processed with DIO. Resonant Auger decay spectra were obtained and analyzed using the core-hole clock (CHC) method. An enhancement in the charge transfer process was observed for thermally annealed films, especially for samples processed with DIO, corresponding to an increase in film ordering. Furthermore, the investigated films were characterized using X-ray photoelectron spectroscopy, attesting to the presence of the thiophene unit in the samples and demonstrating that some of its sulfur atoms were positively polarized in the F8T2 films. All these experimental findings were compared with molecular dynamics (MD) simulations of film evaporation with and without DIO. The use of MD, together with mathematical modeling, was able to explain the major effects found in the experiments, including the polarization of sulfur atoms. The simultaneous use of powerful spectroscopic techniques and theoretical methods shed light on key aspects linking film morphology with fabrication procedures.

Published
2024
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9. Inducing molecular orientation in solution-processed thin films of fluorene-bithiophene-based copolymer: thermal annealing vs. solvent additive

Author

Coutinho Pereira, Cassia Ferreira, primary, Borges, Bruno G. A. L., additional, Sousa, Karlison R. A., additional, Holakoei, Soheila, additional, Roman, Lucimara S., additional, Araujo, C. Moyses, additional, Cremona, Marco, additional, Koehler, Marlus, additional, Marchiori, Cleber F. N., additional, and Rocco, Maria Luiza M., additional

Published
2024
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18. Site‐selective Mono‐ and Bifunctionalization of Graphene Oxide: Screening Nanocatalysts for Organophosphate Degradation.

Author

Santos, Yane H., Martinez, André H. G., Veiga, Amanda Garcez, Rocco, Maria Luiza M., Zarbin, Aldo J. G., and Orth, Elisa S.

Subjects
NANOPARTICLES, GRAPHENE oxide, SULFHYDRYL group, CARBOXYLIC acids, CHEMICAL warfare, FENITROTHION
Abstract

Targeted multiple functionalization is a promising tool for developing nanocatalysts for the degradation of toxic organophosphates, present in many agrochemicals and chemical warfare. Herein, we functionalized graphene oxide with two different functional groups (thiol and imidazole), focused on two distinct anchoring sites: epoxide and carboxylic acids. The mono‐ and bifunctionalized materials showed pronounced catalytic activity in the degradation of a toxic organophosphate. This was attributed to cooperative multiple catalyses by the reactive imidazole/thiol groups and neighbouring groups (carboxylate/hydroxyl) on the nanocatalyst backbone. The best nanocatalyst was monofunctionalized via epoxides, which showed the lowest degree of functionalization and highest amount of carboxylic acids. In this case, it could benefit from a bifunctional nucleophilic and general base catalysis involving the thiol and carboxylate groups, respectively. The bifunctionalization strategy via both epoxide and carboxylic acids showed to be better than the analogue bifunctionalized solely via the carboxylic acids, evidencing the importance of the spatial distribution of the anchoring sites. Overall, the functionalization strategy varies the positioning and availability of reactive groups which directly affects the catalytic outcome. [ABSTRACT FROM AUTHOR]

Published
2024
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20. Generalization of the post-collision interaction effect from gas-phase to solid-state systems demonstrated in thiophene and its polymers

Author

Velasquez, Nicolas, Travnikova, Oksana, Guillemin, Renaud, Ismail, Iyas, Journel, Loic, Martins, Jessica B., Koulentianos, Dimitris, Céolin, Denis, Fillaud, Laure, Rocco, Maria Luiza M., Püttner, Ralph, Piancastelli, Maria Novella, Simon, Marc, Sheinerman, Sergei, Gerchikov, Leonid, Marchenko, Tatiana, Velasquez, Nicolas, Travnikova, Oksana, Guillemin, Renaud, Ismail, Iyas, Journel, Loic, Martins, Jessica B., Koulentianos, Dimitris, Céolin, Denis, Fillaud, Laure, Rocco, Maria Luiza M., Püttner, Ralph, Piancastelli, Maria Novella, Simon, Marc, Sheinerman, Sergei, Gerchikov, Leonid, and Marchenko, Tatiana

Abstract

We demonstrate experimentally and theoretically the presence of the post-collision interaction (PCI) effect in sulfur KL2,3L2,3 Auger electron spectra measured in the gas-phase thiophene and in solid-state organic polymers: polythiophene (PT) and poly(3-hexylthiophene-2,5-diyl), commonly known as P3HT. PCI manifests itself through a distortion and a blueshift of the normal Auger S KL2,3L2,3 spectrum when S 1s ionization occurs close to the ionization threshold. Our investigation shows that the PCI-induced shift of the Auger spectra is stronger in the solid-state polymers than in the gas-phase organic molecule. Theoretical modeling within the framework of the eikonal approximation provides good agreement with the experimental observations. In a solid medium, two effects influence the interaction between the photoelectron and the Auger electron. In detail, stronger PCI in the polymers is attributed to the photoelectron scattering in the solid, which overcompensates the polarization screening of electron charges which causes a reduction of the interaction. Our paper demonstrates the general nature of the PCI effect occurring in different media.

Published
2023
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22. Generalization of the post-collision interaction effect from gas-phase to solid-state systems demonstrated in thiophene and its polymers

Author

Velasquez, Nicolas, primary, Travnikova, Oksana, additional, Guillemin, Renaud, additional, Ismail, Iyas, additional, Journel, Loïc, additional, Martins, Jessica B., additional, Koulentianos, Dimitris, additional, Céolin, Denis, additional, Fillaud, Laure, additional, Rocco, Maria Luiza M., additional, Püttner, Ralph, additional, Piancastelli, Maria Novella, additional, Simon, Marc, additional, Sheinerman, Sergei, additional, Gerchikov, Leonid, additional, and Marchenko, Tatiana, additional

Published
2023
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23. On the energy gap determination of organic optoelectronic materials : the case of porphyrin derivatives

Author

Aderne, Rian E., Borges, Bruno Gabriel A. L., Avila, Harold C., von Kieseritzky, Fredrik, Hellberg, Jonas, Koehler, Marlus, Cremona, Marco, Roman, Lucimara S., Araujo, Moyses, Rocco, Maria Luiza M., Marchiori, Cleber F. N., Aderne, Rian E., Borges, Bruno Gabriel A. L., Avila, Harold C., von Kieseritzky, Fredrik, Hellberg, Jonas, Koehler, Marlus, Cremona, Marco, Roman, Lucimara S., Araujo, Moyses, Rocco, Maria Luiza M., and Marchiori, Cleber F. N.

Abstract

The correct determination of the ionization potential (IP) and electron affinity (EA) as well as the energy gap is essential to properly characterize a series of key phenomena related to the applications of organic semiconductors. For example, energy offsets play an essential role in charge separation in organic photovoltaics. Yet there has been a lot of confusion involving the real physical meaning behind those quantities. Experimentally the energy gap can be measured by direct techniques such as UV-Vis absorption, or indirect techniques such as cyclic voltammetry (CV). Another spectroscopic method is the Reflection Electron Energy Loss Spectroscopy (REELS). Regarding data correlation, there is little consensus on how the REELS' energy gap can be interpreted in light of the energies obtained from other methodologies such as CV, UV-Vis, or photoemission. In addition, even data acquired using those traditional techniques has been misinterpreted or applied to derive conclusions beyond the limits imposed by the physics of the measurement. A similar situation also happens when different theoretical approaches are used to assess the energy gap or employed to explain outcomes from experiments. By using a set of porphyrin derivatives as model molecules, we discuss some key aspects of those important issues. The peculiar properties of these porphyrins demonstrate that even straightforward measurements or calculations performed in a group of very similar molecules need a careful interpretation of the outcomes. Differences up to 660 meV (similar to 190 meV) are found comparing REELS (electrochemical) measurements with UV-Vis energy gaps, for instance. From the theoretical point of view, a reasonable agreement with electrochemical measurements of the IP, EA, and the gap of the porphyrins is only obtained when the calculations involve the full thermodynamics of the redox processes. The purpose of this work is to shed light on the differences and similarities of those aforementi

Published
2022
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24. Electron delocalisation in conjugated sulfur heterocycles probed by resonant Auger spectroscopy

Author

Martins, Jessica B., de Moura, Carlos E., V, Goldsztejn, Gildas, Travnikova, Oksana, Guillemin, Renaud, Ismail, Iyas, Journel, Loic, Koulentianos, Dimitrios, Barbatti, Mario, Lago, Alexsandre F., Ceolin, Denis, Rocco, Maria Luiza M., Püttner, Ralph, Piancastelli, Maria Novella, Simon, Marc, Marchenko, Tatiana, Martins, Jessica B., de Moura, Carlos E., V, Goldsztejn, Gildas, Travnikova, Oksana, Guillemin, Renaud, Ismail, Iyas, Journel, Loic, Koulentianos, Dimitrios, Barbatti, Mario, Lago, Alexsandre F., Ceolin, Denis, Rocco, Maria Luiza M., Püttner, Ralph, Piancastelli, Maria Novella, Simon, Marc, and Marchenko, Tatiana

Abstract

We propose a novel approach for an indirect probing of conjugation and hyperconjugation in core-excited molecules using resonant Auger spectroscopy. Our work demonstrates that the changes in the electronic structure of thiophene (C4H4S) and thiazole (C3H3NS), occurring in the process of resonant sulfur K-shell excitation and Auger decay, affect the stabilisation energy resulting from pi-conjugation and hyperconjugation. The variations in the stabilisation energy manifest themselves in the resonant S KL2,3L2,3 Auger spectra of thiophene and thiazole. The comparison of the results obtained for the conjugated molecules and for thiolane (C4H8S), the saturated analogue of thiophene, has been performed. The experimental observations are interpreted using high-level quantum-mechanical calculations and the natural bond orbital analysis.

Published
2022
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26. Enhancement of conductivity and transmittance of graphene oxide/PEDOT:PSS electrodes and the evaluation of charge transfer dynamics.

Author

das Neves, Matheus Felipe Fagundes, Damasceno, João Paulo Vita, Holakoei, Soheila, Rocco, Maria Luiza M., Zarbin, Aldo José Gorgatti, De Oliveira, Camilla Karla Brites Queiroz Martins, and Roman, Lucimara Stolz

Subjects
ETHYLENE glycol, X-ray absorption near edge structure, RESONANT ultrasound spectroscopy, CHARGE transfer, AUGER effect
Abstract

Poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate), PEDOT:PSS, is a polymeric composite that can substitute indium tin oxide (ITO), enabling ITO-free organic devices. However, PEDOT:PSS films have conductivities two orders of magnitude lower than ITO due to the presence of PSS, an insulator polymer added to provide water dispersion to PEDOT. To enhance the electrical performance of the films and overcome the insulator limitations, we prepared thin films of graphene oxide (GO) and PEDOT:PSS composites. The dried films were then treated with ethylene glycol (EG). An increment of two orders of magnitude in conductivity values was observed, as well as an increase in transmittance at the visible region. Also, GO:PEDOT:PSS thin films became more hydrophobic due to the partial removal of PSS. The mass ratio that is equal to 0.058 of GO/PEDOT provides higher electrical conductivity due to higher chain orientation of PEDOT as seen in the near edge X-ray absorption fine structure and resonant Auger spectroscopy measurements. The electrical transport follows the Mott Variable Range Hopping model for low temperature, showing that the conduction occurs in three dimensions. The solvent treatment increases the characteristic conductivity and decreases the activation hopping energy, with the characteristic temperature remaining almost unchanged. It indicates that the EG treatment promotes a decrease in charge transfer time and resistivity. [ABSTRACT FROM AUTHOR]

Published
2019
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29. 3d transition metal coordination on monolayer MoS2: a facile doping method to functionalize surfaces

Author

Liu, He, primary, Silva, Walner Costa, additional, Santana Gonçalves de Souza, Leonardo, additional, Veiga, Amanda Garcez, additional, Seixas, Leandro, additional, Fujisawa, Kazunori, additional, Kahn, Ethan, additional, Zhang, Tianyi, additional, Zhang, Fu, additional, Yu, Zhuohang, additional, Thompson, Katherine, additional, Lei, Yu, additional, de Matos, Christiano J. S., additional, Rocco, Maria Luiza M., additional, Terrones, Mauricio, additional, and Grasseschi, Daniel, additional

Published
2022
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30. Electron delocalisation in conjugated sulfur heterocycles probed by resonant Auger spectroscopy

Author

Martins, Jessica B., primary, de Moura, Carlos E. V., additional, Goldsztejn, Gildas, additional, Travnikova, Oksana, additional, Guillemin, Renaud, additional, Ismail, Iyas, additional, Journel, Loïc, additional, Koulentianos, Dimitrios, additional, Barbatti, Mario, additional, Lago, Alexsandre F., additional, Céolin, Denis, additional, Rocco, Maria Luiza M., additional, Püttner, Ralph, additional, Piancastelli, Maria Novella, additional, Simon, Marc, additional, and Marchenko, Tatiana, additional

Published
2022
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31. On the energy gap determination of organic optoelectronic materials: the case of porphyrin derivatives

Author

Aderne, Rian E., primary, Borges, Bruno Gabriel A. L., additional, Ávila, Harold C., additional, von Kieseritzky, Fredrik, additional, Hellberg, Jonas, additional, Koehler, Marlus, additional, Cremona, Marco, additional, Roman, Lucimara S., additional, Araujo, C. Moyses, additional, Rocco, Maria Luiza M., additional, and Marchiori, Cleber F. N., additional

Published
2022
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34. Spectroscopic study of D1–A–D2–A terpolymer films for optoelectronic applications.

Author

Correa, Roger S., Santos, Bianca P. S., Ribeiro, Arthur C., da Silva, Luiz Alberto F., Péan, Emmanuel V., Davies, Matthew L., Marques, Maria de Fátima V., and Rocco, Maria Luiza M.

Abstract

Several strategies have been considered in search of more efficient organic materials for charge transfer in photovoltaic devices. Among them, the integration of donor–acceptor (D–A) functional units on a conjugated copolymer has been widely applied. In this framework, we evaluated four terpolymers made up of donor moieties derived from 9,9-dioctylfluorene and 9-(heptadecan-9-yl)-9H-carbazole combined with 2,1,3-benzothiadiazole, the acceptor moiety, in different monomer ratios and polymerization routes (block and random microstructures). The preferred molecular orientation and charge transfer dynamics of the polymeric films were assessed by near edge X-ray absorption fine structure spectroscopy (NEXAFS) and resonant Auger electron spectroscopy (RAES) around the sulfur K-edge. Charge transfer times (τCT) were estimated by the Core–Hole Clock (CHC) method. Films with a high degree of organization were identified for the block terpolymer and random terpolymers with uneven amounts of donor units, showing a preferred orientation of the benzothiadiazole (BT) molecular plane parallel to the substrate surface. The values of τCT measured for all terpolymers were higher than those for typical polymers used in photovoltaic devices, which is not desirable for this type of optoelectronic application, but this may be correlated to the strong acceptor character of BT, the unit probed. To investigate the effect of film formation on the excited state behavior, steady-state and time-resolved photoluminescence measurements were also conducted. X-ray photoelectron spectroscopy (XPS) was employed to characterize the surface chemical composition of the terpolymer films. Based on the spectroscopic data the block copolymer appears to be the most suitable for the desired application. [ABSTRACT FROM AUTHOR]

Published
2022
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39. An investigation on the effect of the monomer/catalyst ratio in the electronic properties of poly(3-hexylthiophene) using XPS, REELS and UPS techniques

Author

Silva Santos, Bianca Pedroso, primary, Rubio Arias, Jose Jonathan, additional, Albuquerque, Lais Schmidt, additional, da Veiga, Amanda Garcez, additional, de Melo Furtado, Jose Geraldo, additional, de Castro Ribeiro, Arthur, additional, da Silva, Luiz Alberto Ferreira, additional, Bendinelli, Elber Vidigal, additional, Rocco, Maria Luiza M., additional, Valaski, Rogério, additional, and Vieira Marques, Maria de Fátima, additional

Published
2019
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47. Cover Image, Volume 66, Issue 10

Author

Bregadiolli, Bruna A, primary, Ramanitra, Hasina H, additional, Ferreira, Rodrigo Marques, additional, Corcoles, Laura, additional, Gomes, Milton S, additional, Kang, Lauren, additional, Combe, Craig MS, additional, Silva, Hugo Santos, additional, Lavarda, Francisco C, additional, Bégué, Didier, additional, Dagron-Lartigau, Christine, additional, Rocco, Maria Luiza M, additional, Luscombe, Christine K, additional, Olivati, Clarissa A, additional, Graeff, Carlos FO, additional, and Hiorns, Roger C, additional

Published
2017
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48. Towards the synthesis of poly(azafulleroid)s: main chain fullerene oligomers for organic photovoltaic devices

Author

Bregadiolli, Bruna A, primary, Ramanitra, Hasina H, additional, Ferreira, Rodrigo Marques, additional, Corcoles, Laura, additional, Gomes, Milton S, additional, Kang, Lauren, additional, Combe, Craig MS, additional, Silva, Hugo Santos, additional, Lavarda, Francisco C, additional, Bégué, Didier, additional, Dagron‐Lartigau, Christine, additional, Rocco, Maria Luiza M, additional, Luscombe, Christine K, additional, Olivati, Clarissa A, additional, Graeff, Carlos FO, additional, and Hiorns, Roger C, additional

Published
2017
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50. Glycine maxmeal extracts as corrosion inhibitor for mild steel in sulphuric acid solution

Author

Lima, Klícia Carla de Santana de, Paiva, Victor Magno, Perrone, Daniel, Ripper, Beatriz, Simões, Grazieli, Rocco, Maria Luiza M., Veiga, Amanda Garcez da, and D’Elia, Eliane

Abstract

The soybean (Glycine Max) meal extracts inhibitory action, the aqueous extract by infusion (AE), its high molecular weight fraction (HMWF) and the aqueous extract by infusion of a commercially isolated soy protein (CIP) towards the mild steel corrosion in 0.5 mol L−1H2SO4was investigated by weight loss measurements, electrochemical impedance spectroscopy (EIS), and potentiodynamic polarization curves. Additionally, scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS) were used, respectively, to characterize morphologically and chemically the surface. The total content of proteins in the different extracts was determined by a quantitative method, the Biuret methods, as well as by two qualitative methods, the nuclear magnetic resonance (NMR) and sodium dodecyl sulfate-polyacrylamide gel electrophoresis analysis (SDS-PAGE). The AE, its HMWF and CIP extracts acted as good corrosion inhibitors, reaching inhibition efficiencies of 85.2%, 88.7% and 94.8% for 800 mg L−1, respectively, from the jcorrdata. The polarization curves show that these extracts act as mixed-type inhibitor with predominantly cathodic characteristics. The adsorption of components from AE, its HMWF, and CIP on the mild steel surface follows the Langmuir adsorption isotherm. The SEM results indicate that the surface was covered by the inhibitor and the XPS analyses confirm chemical interactions between the extracts components and the mild steel surface. The results obtained with HMWF from AE and CIP suggest that the proteins are probably responsible for the inhibitory action.

Published
2020
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