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Dr. Diogo Santos
Center of Physics and Engineering of Advanced Materials

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0 Chemical Engineering
0 Electrocatalysis
0 Electrochemical Engineering
0 Fuel Cells
0 electrolysis

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Fuel Cells
electrolysis
Electrocatalysis
Electrochemical Engineering

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Short Biography

Diogo M.F. Santos currently works as an Associate Researcher in the Center of Physics and Engineering of Advanced Materials (CeFEMA) of Instituto Superior Técnico (IST, Universidade de Lisboa) studying electrodes and membranes for application in direct liquid fuel cells. D.M.F. Santos was born in Torres Vedras, Portugal, in 1977 and graduated in chemical engineering at IST in 2001. He received a M.Sc. degree in 2006 and a Ph.D. degree in electrochemistry in 2009. His Ph.D. thesis was devoted to the development of the direct borohydride fuel cell. He did a 3-year post-doc in Chemical Engineering in FEUP (Porto University) and IST studying new electrocatalytic materials for hydrogen production by alkaline water electrolysis. Afterwards he did a 2-year post-doc in Materials Science & Engineering developing cathodes for direct borohydride fuel cells in IST and CICECO (Aveiro University). As an Investigador FCT in CeFEMA (2015-2020) he developed low-cost electrocatalysts for application in low-temperature fuel cells. D.M.F. Santos has authored over 100 journal papers and 90 conference proceedings. His current h index is 29 (SCOPUS). He has presented more than 50 oral communications and 60 posters in international conferences. He is a member of several renowned international societies and serves as a reviewer for over 80 different scientific journals. His main research interests are related to electrochemical energy conversion and storage.

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Review
Published: 29 May 2021 in Energies
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Environmental issues make the quest for better and cleaner energy sources a priority. Worldwide, researchers and companies are continuously working on this matter, taking one of two approaches: either finding new energy sources or improving the efficiency of existing ones. Hydrogen is a well-known energy carrier due to its high energy content, but a somewhat elusive one for being a gas with low molecular weight. This review examines the current electrolysis processes for obtaining hydrogen, with an emphasis on alkaline water electrolysis. This process is far from being new, but research shows that there is still plenty of room for improvement. The efficiency of an electrolyzer mainly relates to the overpotential and resistances in the cell. This work shows that the path to better electrolyzer efficiency is through the optimization of the cell components and operating conditions. Following a brief introduction to the thermodynamics and kinetics of water electrolysis, the most recent developments on several parameters (e.g., electrocatalysts, electrolyte composition, separator, interelectrode distance) are highlighted.

ACS Style

Ana Santos; Maria-João Cebola; Diogo Santos. Towards the Hydrogen Economy—A Review of the Parameters That Influence the Efficiency of Alkaline Water Electrolyzers. Energies 2021, 14, 3193 .

AMA Style

Ana Santos, Maria-João Cebola, Diogo Santos. Towards the Hydrogen Economy—A Review of the Parameters That Influence the Efficiency of Alkaline Water Electrolyzers. Energies. 2021; 14 (11):3193.

Chicago/Turabian Style

Ana Santos; Maria-João Cebola; Diogo Santos. 2021. "Towards the Hydrogen Economy—A Review of the Parameters That Influence the Efficiency of Alkaline Water Electrolyzers." Energies 14, no. 11: 3193.

Journal article
Published: 29 May 2021 in Nanomaterials
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The synthesis of palladium-based trimetallic catalysts via a facile and scalable synthesis procedure was shown to yield highly promising materials for borohydride-based fuel cells, which are attractive for use in compact environments. This, thereby, provides a route to more environmentally friendly energy storage and generation systems. Carbon-supported trimetallic catalysts were herein prepared by three different routes: using a NaBH4-ethylene glycol complex (PdAuNi/CSBEG), a NaBH4-2-propanol complex (PdAuNi/CSBIPA), and a three-step route (PdAuNi/C3-step). Notably, PdAuNi/CSBIPA yielded highly dispersed trimetallic alloy particles, as determined by XRD, EDX, ICP-OES, XPS, and TEM. The activity of the catalysts for borohydride oxidation reaction was assessed by cyclic voltammetry and RDE-based procedures, with results referenced to a Pd/C catalyst. A number of exchanged electrons close to eight was obtained for PdAuNi/C3-step and PdAuNi/CSBIPA (7.4 and 7.1, respectively), while the others, PdAuNi/CSBEG and Pd/CSBIPA, presented lower values, 2.8 and 1.2, respectively. A direct borohydride-peroxide fuel cell employing PdAuNi/CSBIPA catalyst in the anode attained a power density of 47.5 mW cm−2 at room temperature, while the elevation of temperature to 75 °C led to an approximately four-fold increase in power density to 175 mW cm−2. Trimetallic catalysts prepared via this synthesis route have significant potential for future development.

ACS Style

Ahmed ElSheikh; Gordana Backović; Raisa Oliveira; César Sequeira; James McGregor; Biljana Šljukić; Diogo Santos. Carbon-Supported Trimetallic Catalysts (PdAuNi/C) for Borohydride Oxidation Reaction. Nanomaterials 2021, 11, 1441 .

AMA Style

Ahmed ElSheikh, Gordana Backović, Raisa Oliveira, César Sequeira, James McGregor, Biljana Šljukić, Diogo Santos. Carbon-Supported Trimetallic Catalysts (PdAuNi/C) for Borohydride Oxidation Reaction. Nanomaterials. 2021; 11 (6):1441.

Chicago/Turabian Style

Ahmed ElSheikh; Gordana Backović; Raisa Oliveira; César Sequeira; James McGregor; Biljana Šljukić; Diogo Santos. 2021. "Carbon-Supported Trimetallic Catalysts (PdAuNi/C) for Borohydride Oxidation Reaction." Nanomaterials 11, no. 6: 1441.

Journal article
Published: 25 May 2021 in Journal of Molecular Liquids
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Natural montmorillonite (Mt) is modified with cetyltrimethylammonium bromide (CTAB) for obtaining an organoclay. The physicochemical properties of Mt and CTAB-modified Mt ([email protected]) are characterized by Fourier transform infrared spectroscopy, X-ray diffraction, scanning electron microscopy coupled with energy-dispersive X-ray spectroscopy, nitrogen sorption, and thermogravimetric/differential thermal analysis. The [email protected] is used as an adsorbent for the removal of orange G anionic dye from aqueous solutions. The adsorption process is examined as a function of adsorbent amount, contact time, temperature, pH, and initial dye concentration. The kinetic study indicates that the adsorption equilibrium of orange G dye onto [email protected] is reached after 30 min and fits well to a pseudo-second-order kinetic model. Also, the adsorption isotherm data is best fitted by a Langmuir model, with the maximum adsorption capacity calculated using the non-linear form of the Langmuir isotherm being 167 mg g−1 at 298 K. The statistical physics model shows that the OG dye could be adsorbed with a non-parallel orientation on the surface of [email protected] Finally, [email protected] is successfully employed for the treatment of a real wastewater sample from the textile industry. Molecular dynamics simulations are performed to investigate, on one hand, the structural properties of CTAB intercalated into the 2:1 layered Mt and coated on its external surface, and on the other hand, to provide atomic-level insight on the adsorptive characteristics of orange G dye on [email protected]

ACS Style

Hassan Ouachtak; Anouar El Guerdaoui; Redouane Haounati; Siham Akhouairi; Rachid El Haouti; Naima Hafid; Abdelaziz Ait Addi; Biljana Šljukić; Diogo M.F. Santos; Mohamed Labd Taha. Highly efficient and fast batch adsorption of orange G dye from polluted water using superb organo-montmorillonite: Experimental study and molecular dynamics investigation. Journal of Molecular Liquids 2021, 335, 116560 .

AMA Style

Hassan Ouachtak, Anouar El Guerdaoui, Redouane Haounati, Siham Akhouairi, Rachid El Haouti, Naima Hafid, Abdelaziz Ait Addi, Biljana Šljukić, Diogo M.F. Santos, Mohamed Labd Taha. Highly efficient and fast batch adsorption of orange G dye from polluted water using superb organo-montmorillonite: Experimental study and molecular dynamics investigation. Journal of Molecular Liquids. 2021; 335 ():116560.

Chicago/Turabian Style

Hassan Ouachtak; Anouar El Guerdaoui; Redouane Haounati; Siham Akhouairi; Rachid El Haouti; Naima Hafid; Abdelaziz Ait Addi; Biljana Šljukić; Diogo M.F. Santos; Mohamed Labd Taha. 2021. "Highly efficient and fast batch adsorption of orange G dye from polluted water using superb organo-montmorillonite: Experimental study and molecular dynamics investigation." Journal of Molecular Liquids 335, no. : 116560.

Journal article
Published: 14 May 2021 in Catalysts
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Three different carbon-supported metal (gold, platinum, nickel) nanoparticle (M/c-IL) electrocatalysts are prepared by template-free carbonization of the corresponding ionic liquids, namely [Hmim][AuCl4], [Hmim]2[PtCl4], and [C16mim]2[NiCl4], as confirmed by X-ray diffraction analysis, scanning electron microscopy coupled with energy-dispersive X-ray spectroscopy and Raman spectroscopy. The electrochemical investigation of borohydride oxidation reaction (BOR) at the three electrocatalysts by cyclic voltammetry reveals different behavior for each material. BOR is found to be a first-order reaction at the three electrocatalysts, with an apparent activation energy of 10.6 and 13.8 kJ mol−1 for Pt/c-IL and Au/c-IL electrocatalysts, respectively. A number of exchanged electrons of 5.0, 2.4, and 2.0 is obtained for BOR at Pt/c-IL, Au/c-IL, and Ni/c-IL electrodes, respectively. Direct borohydride-peroxide fuel cell (DBPFC) tests done at temperatures in the 25–65 °C range show ca. four times higher power density when using a Pt/c-IL anode than with an Au/c-IL anode. Peak power densities of 40.6 and 120.5 mW cm−2 are achieved at 25 and 65 °C, respectively, for DBPFC with a Pt/c-IL anode electrocatalyst.

ACS Style

Jadranka Milikić; Raisa Oliveira; Andres Tapia; Diogo Santos; Nikola Zdolšek; Tatjana Trtić-Petrović; Milan Vraneš; Biljana Šljukić. Ionic Liquid-Derived Carbon-Supported Metal Electrocatalysts as Anodes in Direct Borohydride-Peroxide Fuel Cells. Catalysts 2021, 11, 632 .

AMA Style

Jadranka Milikić, Raisa Oliveira, Andres Tapia, Diogo Santos, Nikola Zdolšek, Tatjana Trtić-Petrović, Milan Vraneš, Biljana Šljukić. Ionic Liquid-Derived Carbon-Supported Metal Electrocatalysts as Anodes in Direct Borohydride-Peroxide Fuel Cells. Catalysts. 2021; 11 (5):632.

Chicago/Turabian Style

Jadranka Milikić; Raisa Oliveira; Andres Tapia; Diogo Santos; Nikola Zdolšek; Tatjana Trtić-Petrović; Milan Vraneš; Biljana Šljukić. 2021. "Ionic Liquid-Derived Carbon-Supported Metal Electrocatalysts as Anodes in Direct Borohydride-Peroxide Fuel Cells." Catalysts 11, no. 5: 632.

Erratum
Published: 09 February 2021 in Journal of Alloys and Compounds
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ACS Style

Marta Martins; Biljana Šljukić; Önder Metin; Melike Sevim; César Sequeira; Tansel Sener; Diogo M.F. Santos. Corrigendum to “Bimetallic PdM (M: Fe, Ag, Au) alloy nanoparticles assembled on reduced graphene oxide as catalysts for direct borohydride fuel cells” [J. Alloy. Compd. 718 (2017) 204–214]. Journal of Alloys and Compounds 2021, 863, 159018 .

AMA Style

Marta Martins, Biljana Šljukić, Önder Metin, Melike Sevim, César Sequeira, Tansel Sener, Diogo M.F. Santos. Corrigendum to “Bimetallic PdM (M: Fe, Ag, Au) alloy nanoparticles assembled on reduced graphene oxide as catalysts for direct borohydride fuel cells” [J. Alloy. Compd. 718 (2017) 204–214]. Journal of Alloys and Compounds. 2021; 863 ():159018.

Chicago/Turabian Style

Marta Martins; Biljana Šljukić; Önder Metin; Melike Sevim; César Sequeira; Tansel Sener; Diogo M.F. Santos. 2021. "Corrigendum to “Bimetallic PdM (M: Fe, Ag, Au) alloy nanoparticles assembled on reduced graphene oxide as catalysts for direct borohydride fuel cells” [J. Alloy. Compd. 718 (2017) 204–214]." Journal of Alloys and Compounds 863, no. : 159018.

Journal article
Published: 28 December 2020 in Materials
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Bimetallic cobalt (Co)-based coatings were prepared by a facile, fast, and low-cost electroless deposition on a copper substrate (CoFe, CoMn, CoMo) and characterized by scanning electron microscopy with energy dispersive X-ray spectroscopy and X-ray diffraction analysis. Prepared coatings were thoroughly examined for hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) in alkaline solution (1 M potassium hydroxide, KOH) and their activity compared to that of Co and Ni coatings. All five coatings showed activity for both reactions, where CoMo and Co showed the highest activity for HER and OER, respectively. Namely, the highest HER current density was recorded at CoMo coating with low overpotential (61 mV) to reach a current density of 10 mA·cm−2. The highest OER current density was recorded at Co coating with a low Tafel slope of 60 mV·dec−1. Furthermore, these coatings proved to be stable under HER and OER polarization conditions.

ACS Style

Jadranka Milikić; Aldona Balčiūnaitė; Zita Sukackienė; Dušan MladenoviĆ; Diogo M. F. Santos; Loreta Tamašauskaitė-Tamašiūnaitė; Biljana Šljukić. Bimetallic Co-Based (CoM, M = Mo, Fe, Mn) Coatings for High-Efficiency Water Splitting. Materials 2020, 14, 92 .

AMA Style

Jadranka Milikić, Aldona Balčiūnaitė, Zita Sukackienė, Dušan MladenoviĆ, Diogo M. F. Santos, Loreta Tamašauskaitė-Tamašiūnaitė, Biljana Šljukić. Bimetallic Co-Based (CoM, M = Mo, Fe, Mn) Coatings for High-Efficiency Water Splitting. Materials. 2020; 14 (1):92.

Chicago/Turabian Style

Jadranka Milikić; Aldona Balčiūnaitė; Zita Sukackienė; Dušan MladenoviĆ; Diogo M. F. Santos; Loreta Tamašauskaitė-Tamašiūnaitė; Biljana Šljukić. 2020. "Bimetallic Co-Based (CoM, M = Mo, Fe, Mn) Coatings for High-Efficiency Water Splitting." Materials 14, no. 1: 92.

Journal article
Published: 10 December 2020 in Journal of Alloys and Compounds
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Gold-rare earth (Au-RE) alloys with equiatomic compositions are prepared by arc (RE = Dy, Ho, Y) or induction (RE = Sm) melting. Morphology and phase composition is assessed by scanning electron microscopy coupled with energy-dispersive X-ray spectroscopy (SEM-EDXS), while X-ray powder diffraction (XRPD) is used to confirm crystal structures. The Au-RE electrodes are evaluated for borohydride oxidation reaction (BOR) in alkaline media employing cyclic voltammetry and chronoamperometry. The obtained data allows calculation of kinetic parameters that characterise the borohydride (BH4-) oxidation at Au-RE alloys, including the number of exchanged electrons, n, and the anodic charge transfer coefficient, α. n values range from 2.4 to 4.4, while α values are found to be in the 0.60–0.83 range. The BOR apparent activation energy, Eaapp, and the reaction order, β, are also determined from CV data obtained at different temperatures and different BH4- concentrations, respectively. Low Eaapp values range from 16.4 (Au-Sm) to 20.2 kJ mol-1 (Au-Y) and β values suggest that BOR at the examined alloys is a 1st order reaction with respect to BH4- concentration. A small-scale direct borohydride-peroxide fuel cell (DBPFC) operating with Au-Y anode at 25 ºC reaches a peak power density of 150 mW cm-2. The cell performance is enhanced when increasing the temperature to 45 ºC, with a maximum power density of 215 mW cm-2 being attained.

ACS Style

Gordana Backović; Jadranka Milikić; Serena De Negri; Adriana Saccone; Biljana Šljukić; Diogo M.F. Santos. Enhanced borohydride oxidation kinetics at gold-rare earth alloys. Journal of Alloys and Compounds 2020, 857, 158273 .

AMA Style

Gordana Backović, Jadranka Milikić, Serena De Negri, Adriana Saccone, Biljana Šljukić, Diogo M.F. Santos. Enhanced borohydride oxidation kinetics at gold-rare earth alloys. Journal of Alloys and Compounds. 2020; 857 ():158273.

Chicago/Turabian Style

Gordana Backović; Jadranka Milikić; Serena De Negri; Adriana Saccone; Biljana Šljukić; Diogo M.F. Santos. 2020. "Enhanced borohydride oxidation kinetics at gold-rare earth alloys." Journal of Alloys and Compounds 857, no. : 158273.

Journal article
Published: 05 November 2020 in Journal of Environmental Chemical Engineering
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The electrochemical behavior of raw and anaerobically pretreated swine wastewater was studied for energy recovery and water treatment. Voltammetric studies using platinum (Pt) electrodes have shown the existence of a characteristic anodic peak, possibly corresponding to the electrooxidation of aromatic compounds in solution. Kinetic parameters taken from Tafel analysis demonstrated the superior performance of Pt for hydrogen evolution reaction in comparison to nickel (Ni). Consecutive electrolysis using Ni electrodes showed that these modestly reduced the chemical oxygen demand (COD) from the wastewater (12.3 ± 1.61 % and 12.7 ± 0.88 % removal for the raw (RW) and digested (DW) wastewater, respectively). On the other hand, graphite anodes achieved degradations of 37.0 ± 1.97 % and 25.5 ± 2.95 % COD removal for RW and DW. The results were confirmed by fitting a pseudo-first-order model and suggest different oxidation mechanisms at the two electrodes. Meanwhile, Fourier-transform infrared spectra demonstrated that biological pretreatment affected the bioavailability of aliphatic compounds, such as saccharides, peptides, and fats, while thermogravimetric analysis reflected the degree of biological stabilization of both swine solutions. These findings indicate that SW offers high potential as an electrolyte solution to following this new electrochemical approach to the valorization of SW.

ACS Style

G. Lourinho; D.M.F. Santos; P.S.D. Brito. Electrooxidation studies of swine effluents before and after the anaerobic digestion process. Journal of Environmental Chemical Engineering 2020, 9, 104712 .

AMA Style

G. Lourinho, D.M.F. Santos, P.S.D. Brito. Electrooxidation studies of swine effluents before and after the anaerobic digestion process. Journal of Environmental Chemical Engineering. 2020; 9 (2):104712.

Chicago/Turabian Style

G. Lourinho; D.M.F. Santos; P.S.D. Brito. 2020. "Electrooxidation studies of swine effluents before and after the anaerobic digestion process." Journal of Environmental Chemical Engineering 9, no. 2: 104712.

Journal article
Published: 10 September 2020 in Nanomaterials
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Molybdenum carbide (Mo2C)-based electrocatalysts were prepared using two different carbon supports, commercial carbon nanotubes (CNTs) and synthesised carbon xerogel (CXG), to be studied from the point of view of both capacitive and electrocatalytic properties. Cation type (K+ or Na+) in the alkaline electrolyte solution did not affect the rate of formation of the electrical double layer at a low scan rate of 10 mV s−1. Conversely, the different mobility of these cations through the electrolyte was found to be crucial for the rate of double-layer formation at higher scan rates. Molybdenum carbide supported on carbon xerogel (Mo2C/CXG) showed ca. 3 times higher double-layer capacity amounting to 75 mF cm−2 compared to molybdenum carbide supported on carbon nanotubes (Mo2C/CNT) with a value of 23 mF cm−2 due to having more than double the surface area size. The electrocatalytic properties of carbon-supported molybdenum carbides for the oxygen reduction reaction in alkaline media were evaluated using linear scan voltammetry with a rotating disk electrode. The studied materials demonstrated good electrocatalytic performance with Mo2C/CXG delivering higher current densities at more positive onset and half-wave potential. The number of electrons exchanged during oxygen reduction reaction (ORR) was calculated to be 3, suggesting a combination of four- and two-electron mechanism.

ACS Style

Dušan Mladenović; Milica Vujković; Slavko Mentus; Diogo Santos; Raquel Rocha; Cesar C. Sequeira; José Figueiredo; Biljana Šljukić. Carbon-Supported Mo2C for Oxygen Reduction Reaction Electrocatalysis. Nanomaterials 2020, 10, 1805 .

AMA Style

Dušan Mladenović, Milica Vujković, Slavko Mentus, Diogo Santos, Raquel Rocha, Cesar C. Sequeira, José Figueiredo, Biljana Šljukić. Carbon-Supported Mo2C for Oxygen Reduction Reaction Electrocatalysis. Nanomaterials. 2020; 10 (9):1805.

Chicago/Turabian Style

Dušan Mladenović; Milica Vujković; Slavko Mentus; Diogo Santos; Raquel Rocha; Cesar C. Sequeira; José Figueiredo; Biljana Šljukić. 2020. "Carbon-Supported Mo2C for Oxygen Reduction Reaction Electrocatalysis." Nanomaterials 10, no. 9: 1805.

Journal article
Published: 24 July 2020 in International Journal of Hydrogen Energy
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Described herein is a new catalytic material comprising Fe-BTC (Basolite F-300) metal-organic framework stabilized ruthenium nanoparticles ([email protected]) and its notable catalytic activity for the borohydride oxidation reaction (BOR). [email protected] catalyst was reproducibly prepared by gas-phase infiltration of Ru (cod) (cot) (cod = 1,5-cyclooctadiene and cot = 1,3,5-cyclooctatriene) precursor followed by hydrogenolysis of the inclusion compound Ru (cod) (cot)@Fe-BTC to form the [email protected] The resulting catalytic material was characterized by using multi-pronged techniques and the sum of their results revealed the formation of well-dispersed, highly crystalline, and small-sized ruthenium nanoparticles (3.9 nm) within the framework of Fe-BTC by preserving its crystalline structure. Cyclic and linear scan voltammetry as well as chronoamperometry techniques were used to assess the catalytic activity and stability of [email protected] for BOR in strongly alkaline medium at different temperatures (25–65 °C) and sodium borohydride concentrations (0.01–0.12 M). The charge transfer coefficient was determined to be 0.85 and BOR at [email protected] was found to be a nearly first-order reaction, with the activation energy amounting to 17 kJ mol−1. A small-scale direct borohydride/peroxide fuel cell that was assembled using [email protected] as an anodic catalyst delivered a maximum power density of 169 mW cm−2 at 65 °C.

ACS Style

Gordana Backovic; Biljana Šljukić; Gulsah Saydan Kanberoglu; Mehmet Yurderib; Ahmet Bulutb; Mehmet Zahmakiranb; Diogo M.F. Santos. Ruthenium(0) nanoparticles stabilized by metal-organic framework as an efficient electrocatalyst for borohydride oxidation reaction. International Journal of Hydrogen Energy 2020, 45, 27056 -27066.

AMA Style

Gordana Backovic, Biljana Šljukić, Gulsah Saydan Kanberoglu, Mehmet Yurderib, Ahmet Bulutb, Mehmet Zahmakiranb, Diogo M.F. Santos. Ruthenium(0) nanoparticles stabilized by metal-organic framework as an efficient electrocatalyst for borohydride oxidation reaction. International Journal of Hydrogen Energy. 2020; 45 (51):27056-27066.

Chicago/Turabian Style

Gordana Backovic; Biljana Šljukić; Gulsah Saydan Kanberoglu; Mehmet Yurderib; Ahmet Bulutb; Mehmet Zahmakiranb; Diogo M.F. Santos. 2020. "Ruthenium(0) nanoparticles stabilized by metal-organic framework as an efficient electrocatalyst for borohydride oxidation reaction." International Journal of Hydrogen Energy 45, no. 51: 27056-27066.

Journal article
Published: 21 July 2020 in Journal of Energy Chemistry
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Problems associated with carbon support corrosion under operating fuel cell conditions require the identification of alternative supports for platinum-based nanosized electrocatalysts. Platinum supported on manganese vanadate (Pt/MnV2O6) was prepared by microwave irradiation method and characterized using X-ray diffraction, Fourier-transform infrared spectroscopy, X-ray photoelectron spectroscopy, scanning electron microscopy with energy dispersive spectroscopy, and transmission electron microscopy. The borohydride oxidation reaction (BOR) on Pt/MnV2O6 was studied in highly alkaline media using voltammetry, chronoamperometry, and electrochemical impedance spectroscopy. BOR electrocatalytic activity of Pt/MnV2O6 was also compared with that of commercial Pt/C (46 wt% Pt) electrocatalyst. The apparent activation energy of BOR at Pt/MnV2O6 was estimated to be 32 kJ mol−1 and the order of reaction to be 0.51, indicating that borohydride hydrolysis proceeds in parallel with its oxidation. Long-term stability of Pt/MnV2O6 under BOR typical conditions was observed. A laboratory-scale direct borohydride fuel cell assembled with a Pt/MnV2O6 anode reached a specific power of 274 W g−1. Experimental results on Pt/MnV2O6 were complemented by DFT calculations, which indicated good adherence of Pt to MnV2O6, beneficial for electrocatalyst stability.

ACS Style

Jadranka Milikić; Marta Martins; Ana S. Dobrota; Gamze Bozkurt; Gulin S.P. Soylu; Ayşe B. Yurtcan; Natalia V. Skorodumova; Igor A. Pašti; Biljana Šljukić; Diogo M.F. Santos. A Pt/MnV2O6 nanocomposite for the borohydride oxidation reaction. Journal of Energy Chemistry 2020, 55, 428 -436.

AMA Style

Jadranka Milikić, Marta Martins, Ana S. Dobrota, Gamze Bozkurt, Gulin S.P. Soylu, Ayşe B. Yurtcan, Natalia V. Skorodumova, Igor A. Pašti, Biljana Šljukić, Diogo M.F. Santos. A Pt/MnV2O6 nanocomposite for the borohydride oxidation reaction. Journal of Energy Chemistry. 2020; 55 ():428-436.

Chicago/Turabian Style

Jadranka Milikić; Marta Martins; Ana S. Dobrota; Gamze Bozkurt; Gulin S.P. Soylu; Ayşe B. Yurtcan; Natalia V. Skorodumova; Igor A. Pašti; Biljana Šljukić; Diogo M.F. Santos. 2020. "A Pt/MnV2O6 nanocomposite for the borohydride oxidation reaction." Journal of Energy Chemistry 55, no. : 428-436.

Journal article
Published: 01 May 2020 in International Journal of Hydrogen Energy
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Nanocomposite membranes for low-temperature fuel cells, specifically, direct borohydride fuel cells (DBFCs), are formulated from a ternary polymer blend of poly (vinyl alcohol), poly (vinyl pyrrolidone), and poly (ethylene oxide) with the incorporation of (SO4–TiO2) nanotubes and (PO4–TiO2) as doping agents. The functionalisation of TiO2 is carried out by impregnation-calcination method. Structural and morphological characterisation by FTIR, TEM, SEM, EDX, ICP, and XRD confirmed the successful preparation of the doping materials and their incorporation into the polymer blend. The influence of SO4–TiO2 and PO4–TiO2 doping and their content on the physicochemical properties of the composite membranes is assessed. Water uptake and swelling degree gradually reduced to below 20% with increasing the concentration of TiO2-based doping agent, while the ion exchange capacity raised 3.5 times compared to that of the undoped membrane. The increase of the doping agent content also increased the ionic conductivity, tensile strength and thermal stability of the membrane. DBFC using the composite membrane produced a maximum power density of 75 mW cm−2, close to that using Nafion®117 membrane (81 mW cm−2) but at a significantly lower cost. The promising results obtained in this study pave the way for a simple, green and economic approach for the development of composite membranes for application in DBFCs.

ACS Style

M.H. Gouda; W. Gouveia; N.A. Elessawy; B. Šljukić; Ab.A.A. Nassr; D.M.F. Santos. Simple design of PVA-based blend doped with SO4(PO4)-functionalised TiO2 as an effective membrane for direct borohydride fuel cells. International Journal of Hydrogen Energy 2020, 45, 15226 -15238.

AMA Style

M.H. Gouda, W. Gouveia, N.A. Elessawy, B. Šljukić, Ab.A.A. Nassr, D.M.F. Santos. Simple design of PVA-based blend doped with SO4(PO4)-functionalised TiO2 as an effective membrane for direct borohydride fuel cells. International Journal of Hydrogen Energy. 2020; 45 (30):15226-15238.

Chicago/Turabian Style

M.H. Gouda; W. Gouveia; N.A. Elessawy; B. Šljukić; Ab.A.A. Nassr; D.M.F. Santos. 2020. "Simple design of PVA-based blend doped with SO4(PO4)-functionalised TiO2 as an effective membrane for direct borohydride fuel cells." International Journal of Hydrogen Energy 45, no. 30: 15226-15238.

Paper
Published: 20 April 2020 in Analytical Methods
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Raman spectrometers coupled to cluster analysis were able to identify two polymorphs of quinine sulfate in solid dosage forms. Gold nanoparticles-surface-enhanced Raman scattering with MCR-ALS was used to antimalarial drug quantification in solution.

ACS Style

Sarmento J. Mazivila; Helena I. S. Nogueira; Ricardo N. M. J. Páscoa; David S. M. Ribeiro; João L. M. Santos; João M. M. Leitão; Joaquim C. G. Esteves da Silva. Portable and benchtop Raman spectrometers coupled to cluster analysis to identify quinine sulfate polymorphs in solid dosage forms and antimalarial drug quantification in solution by AuNPs-SERS with MCR-ALS. Analytical Methods 2020, 12, 2407 -2421.

AMA Style

Sarmento J. Mazivila, Helena I. S. Nogueira, Ricardo N. M. J. Páscoa, David S. M. Ribeiro, João L. M. Santos, João M. M. Leitão, Joaquim C. G. Esteves da Silva. Portable and benchtop Raman spectrometers coupled to cluster analysis to identify quinine sulfate polymorphs in solid dosage forms and antimalarial drug quantification in solution by AuNPs-SERS with MCR-ALS. Analytical Methods. 2020; 12 (18):2407-2421.

Chicago/Turabian Style

Sarmento J. Mazivila; Helena I. S. Nogueira; Ricardo N. M. J. Páscoa; David S. M. Ribeiro; João L. M. Santos; João M. M. Leitão; Joaquim C. G. Esteves da Silva. 2020. "Portable and benchtop Raman spectrometers coupled to cluster analysis to identify quinine sulfate polymorphs in solid dosage forms and antimalarial drug quantification in solution by AuNPs-SERS with MCR-ALS." Analytical Methods 12, no. 18: 2407-2421.

Journal article
Published: 17 April 2020 in Materials
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Tungsten oxide nanostructures were modified by oxygen vacancies through hydrothermal treatment. Both the crystalline structure and morphological appearance were completely changed. Spherical WO3·H2O was prepared from tungstic acid solution by aging at room temperature, while rod-like WO3·0.33H2O was prepared by hydrothermal treatment of tungstic acid solution at 120 °C. These structures embedded in sodium alginate (SA)/polyvinylpyrrolidone (PVP) were synthesized as novel porous beads by gelation method into calcium chloride solution. The performance of the prepared materials as photocatalysts is examined for methylene blue (MB) degradation in aqueous solutions. Different operation parameters affecting the dye degradation process, such as light intensity, illumination time, and photocatalyst dosage are investigated. Results revealed that the photocatalytic activity of novel nanocomposite changed with the change in WO3 morphology. Namely, the beads with rod nanostructure of WO3 have shown better effectiveness in MB removal than the beads containing WO3 in spherical form. The maximum degradation efficiency was found to be 98% for WO3 nanorods structure embedded beads, while the maximum removal of WO3 nanospheres structure embedded beads was 91%. The cycling-ability and reuse results recommend both prepared structures to be used as effective tools for treating MB dye-contaminated wastewaters. The results show that the novel SA/PVP/WO3 nanocomposite beads are eco-friendly nanocomposite materials that can be applied as photocatalysts for the degradation of cationic dyes in contaminated water.

ACS Style

Eman M. Elsayed; Mohamed S. Elnouby; M. H. Gouda; Noha A. Elessawy; D. M. F. Santos. Effect of the Morphology of Tungsten Oxide Embedded in Sodium Alginate/Polyvinylpyrrolidone Composite Beads on the Photocatalytic Degradation of Methylene Blue Dye Solution. Materials 2020, 13, 1905 .

AMA Style

Eman M. Elsayed, Mohamed S. Elnouby, M. H. Gouda, Noha A. Elessawy, D. M. F. Santos. Effect of the Morphology of Tungsten Oxide Embedded in Sodium Alginate/Polyvinylpyrrolidone Composite Beads on the Photocatalytic Degradation of Methylene Blue Dye Solution. Materials. 2020; 13 (8):1905.

Chicago/Turabian Style

Eman M. Elsayed; Mohamed S. Elnouby; M. H. Gouda; Noha A. Elessawy; D. M. F. Santos. 2020. "Effect of the Morphology of Tungsten Oxide Embedded in Sodium Alginate/Polyvinylpyrrolidone Composite Beads on the Photocatalytic Degradation of Methylene Blue Dye Solution." Materials 13, no. 8: 1905.

Journal article
Published: 08 April 2020 in Analytica Chimica Acta
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This work focused on the combination of CdTe and AgInS2 quantum dots in a dual-emission nanoprobe for the simultaneous determination of folic acid and Fe(II) in pharmaceutical formulations. The surface chemistry of the used QDs was amended with suitable capping ligands to obtain appropriate reactivity in terms of selectivity and sensitivity towards the target analytes. The implementation of PL-based sensing schemes combining multiple QDs of different nature, excited at the same wavelength and emitting at different ones, allowed to obtain a specific analyte-response profile. The first-order fluorescence data obtained from the whole emission spectra of the CdTe/AgInS2 combined nanoprobe upon interaction with folic acid and Fe(II) were processed by using chemometric tools, namely partial least-squares (PLS) and artificial neural network (ANN). This enabled to circumvent the selectivity issues commonly associated with the use of QDs prone to indiscriminate interaction with multiple species, which impair reliable and accurate quantification in complex matrices samples. ANN demonstrated to be the most efficient chemometric model for the simultaneous determination of both analytes in binary mixtures and pharmaceutical formulations due to the non-linear relationship between analyte concentration and fluorescence data that it could handle. The R2P and SEP% obtained for both analytes quantification in pharmaceutical formulations through ANN modelling ranged from 0.92 to 0.99 and 5.7–9.1%, respectively. The obtained results revealed that the developed approach is able to quantify, with high reliability and accuracy, more than one analyte in complex mixtures and real samples with pharmaceutical interest.

ACS Style

Rafael C. Castro; David S.M. Ribeiro; Ricardo N.M.J. Páscoa; José Soares; Sarmento J. Mazivila; João L.M. Santos. Dual-emission CdTe/AgInS2 photoluminescence probe coupled to neural network data processing for the simultaneous determination of folic acid and iron (II). Analytica Chimica Acta 2020, 1114, 29 -41.

AMA Style

Rafael C. Castro, David S.M. Ribeiro, Ricardo N.M.J. Páscoa, José Soares, Sarmento J. Mazivila, João L.M. Santos. Dual-emission CdTe/AgInS2 photoluminescence probe coupled to neural network data processing for the simultaneous determination of folic acid and iron (II). Analytica Chimica Acta. 2020; 1114 ():29-41.

Chicago/Turabian Style

Rafael C. Castro; David S.M. Ribeiro; Ricardo N.M.J. Páscoa; José Soares; Sarmento J. Mazivila; João L.M. Santos. 2020. "Dual-emission CdTe/AgInS2 photoluminescence probe coupled to neural network data processing for the simultaneous determination of folic acid and iron (II)." Analytica Chimica Acta 1114, no. : 29-41.

Journal article
Published: 02 April 2020 in Energies
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Proton exchange membrane fuel cells and direct alcohol fuel cells have been extensively studied over the last three decades or so. They have emerged as potential systems to power portable applications, providing clean energy, and offering good commercial viability. Ethanol is considered one of the most interesting fuels in this field. Herein, platinum-rare earth (Pt-RE) binary alloys (RE = Ce, Sm, Ho, Dy, nominal composition 50 at.% Pt) were produced and studied as anodes for ethanol oxidation reaction (EOR) in alkaline medium. A Pt-Dy alloy with nominal composition 40 at.% Pt was also tested. Their electrocatalytic performance was evaluated by voltammetric and chronoamperometric measurements in 2 M NaOH solution with different ethanol concentrations (0.2–0.8 M) in the 25–45 °C temperature range. Several EOR kinetic parameters were determined for the Pt-RE alloys, namely the charge transfer and diffusion coefficients, and the number of exchanged electrons. Charge transfer coefficients ranging from 0.60 to 0.69 and n values as high as 0.7 were obtained for the Pt0.5Sm0.5 electrode. The EOR reaction order at the Pt-RE alloys was found to vary between 0.4 and 0.9. The Pt-RE electrodes displayed superior performance for EOR than bare Pt, with Pt0.5Sm0.5 exhibiting the highest electrocatalytic activity. The improved electrocatalytic activity in all of the evaluated Pt-RE binary alloys suggests a strategy for the solution of the existing anode issues due to the structure-sensitive EOR.

ACS Style

D.M.F. Santos; J.R.B. Lourenço; D. Macciò; A. Saccone; C.A.C. Sequeira; José Figueiredo. Ethanol Electrooxidation at Platinum-Rare Earth (RE = Ce, Sm, Ho, Dy) Binary Alloys. Energies 2020, 13, 1658 .

AMA Style

D.M.F. Santos, J.R.B. Lourenço, D. Macciò, A. Saccone, C.A.C. Sequeira, José Figueiredo. Ethanol Electrooxidation at Platinum-Rare Earth (RE = Ce, Sm, Ho, Dy) Binary Alloys. Energies. 2020; 13 (7):1658.

Chicago/Turabian Style

D.M.F. Santos; J.R.B. Lourenço; D. Macciò; A. Saccone; C.A.C. Sequeira; José Figueiredo. 2020. "Ethanol Electrooxidation at Platinum-Rare Earth (RE = Ce, Sm, Ho, Dy) Binary Alloys." Energies 13, no. 7: 1658.

Short communication
Published: 20 March 2020 in Talanta
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The present short communication reports a promising analytical method for authentication of milk based on first-order near-infrared (NIR) spectroscopic data coupled to data driven soft independent modeling of class analogy (DD-SIMCA). This one-class classifier was able to correctly classify all samples of genuine milk powder as members of the target class from samples of milk powder adulterated with melamine and sucrose in a concentration range of 0.8–2% (w/w) and 1–3% (w/w), respectively. Multivariate curve resolution − alternating least-squares (MCR-ALS) was applied as a complementary chemometric model to DD-SIMCA aimed at retrieving pure profiles, allowing to identify the chemical composition of samples properly attributed in the target class or not, providing further investigation from forensic point of view. In order to extend the prime focus of the present report, which was aimed at developing an appropriate chemometric model for authentication purposes, the quantification analysis was also performed. This was done by successful bilinear data decomposition of NIR spectra into pure profiles for the contributing components contained in the system studied (milk and adulterants), allowing to quantify analytes with strong overlapping profiles, even in the presence of an uncalibrated interferent, as demonstrated in this short communication using MCR-ALS under various constraints in order to decrease the rotational ambiguity.

ACS Style

Sarmento J. Mazivila; Ricardo Páscoa; Rafael Catarino Castro; David Ribeiro; João L.M. Santos. Detection of melamine and sucrose as adulterants in milk powder using near-infrared spectroscopy with DD-SIMCA as one-class classifier and MCR-ALS as a means to provide pure profiles of milk and of both adulterants with forensic evidence: A short communication. Talanta 2020, 216, 120937 .

AMA Style

Sarmento J. Mazivila, Ricardo Páscoa, Rafael Catarino Castro, David Ribeiro, João L.M. Santos. Detection of melamine and sucrose as adulterants in milk powder using near-infrared spectroscopy with DD-SIMCA as one-class classifier and MCR-ALS as a means to provide pure profiles of milk and of both adulterants with forensic evidence: A short communication. Talanta. 2020; 216 ():120937.

Chicago/Turabian Style

Sarmento J. Mazivila; Ricardo Páscoa; Rafael Catarino Castro; David Ribeiro; João L.M. Santos. 2020. "Detection of melamine and sucrose as adulterants in milk powder using near-infrared spectroscopy with DD-SIMCA as one-class classifier and MCR-ALS as a means to provide pure profiles of milk and of both adulterants with forensic evidence: A short communication." Talanta 216, no. : 120937.

Journal article
Published: 04 March 2020 in Energies
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Organic–inorganic nanocomposite membranes for potential application in direct borohydride fuel cells (DBFCs) are formulated from sulfonated poly(vinyl alcohol) (SPVA) with the incorporation of (PO4-TiO2) and (SO4-TiO2) nanotubes as doping agents. The functionalization of PVA to SPVA was done by using a 4-sulfophthalic acid as an ionic crosslinker and sulfonating agent. Morphological and structural characterization by transmission electron microscopy (TEM), scanning electron microscopy (SEM), Fourier-transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), energy-dispersive X-ray spectroscopy (EDX) and X-ray diffraction (XRD) confirmed the successful synthesis of the doping agents and their incorporation into the polymer. The influence of PO4-TiO2 and SO4-TiO2 doping and their content on the physicochemical properties of the nanocomposite membranes was evaluated. Swelling degree and water uptake gradually reduced to 7% and 13%, respectively, with increasing doping agent concentration. Ion exchange capacity and ionic conductivity of the membrane with 3 wt.% doping agents were raised 5 and 7 times, respectively, compared to the undoped one. The thermal and oxidative stability and tensile strength also increased with the doping content. Furthermore, lower borohydride permeability (0.32 × 10−6 cm2 s−1) was measured for the membranes with higher amount of inorganic doping agents when compared to the undoped membrane (0.71 × 10−5 cm2 s−1) and Nafion®117 (0.40 × 10−6 cm2 s−1). These results pave the way for a green, simple and low-cost approach for the development of composite membranes for practical DBFCs.

ACS Style

Marwa H. Gouda; Noha A. Elessawy; Diogo M.F. Santos. Synthesis and Characterization of Novel Green Hybrid Nanocomposites for Application as Proton Exchange Membranes in Direct Borohydride Fuel Cells. Energies 2020, 13, 1180 .

AMA Style

Marwa H. Gouda, Noha A. Elessawy, Diogo M.F. Santos. Synthesis and Characterization of Novel Green Hybrid Nanocomposites for Application as Proton Exchange Membranes in Direct Borohydride Fuel Cells. Energies. 2020; 13 (5):1180.

Chicago/Turabian Style

Marwa H. Gouda; Noha A. Elessawy; Diogo M.F. Santos. 2020. "Synthesis and Characterization of Novel Green Hybrid Nanocomposites for Application as Proton Exchange Membranes in Direct Borohydride Fuel Cells." Energies 13, no. 5: 1180.

Journal article
Published: 13 February 2020 in Microchemical Journal
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In this work, the ability of thiomalic acid (TMA)-capped AgInS2 quantum dots to generate reactive oxygen species (ROS) upon irradiation with visible light was investigated, which led to the subsequent development of a luminol-based chemiluminometric method for the monitoring of melatonin (MLT) in commercial dietary supplements. The developed approach was based on the antioxidant properties of melatonin conferred by the electron-rich aromatic indole ring which functions as an electron-donor moiety making it a potent direct scavenger of ROS. This capacity to scavenge free radicals was explored as a quantification process relying on MLT quenching effect on the CL emission of the luminol probe produced upon oxidation by ROS in alkaline medium. The short-lived chemiluminescent species resulting from this reactional scheme were detected by means of a multi-pumping flow system (MPFS) coupled to a photo-irradiation unit in order to allow an efficient control of the irradiation process, to improve the mixture between solutions and to reduce reagents’ consumption. Upon optimization, the obtained results showed a linear relationship between the ratio of CL signal, in the absence (blank) and presence of the analyte (CL0/CL), and melatonin concentration for values of up to 100 mg L−1. The limit of detection was about 0.44 mg L−1.

ACS Style

David Ribeiro; Rafael Catarino Castro; José Soares; João L.M. Santos. Photocatalytic activity of AgInS2 quantum dots upon visible light irradiation for melatonin determination through its reactive oxygen species scavenging effect. Microchemical Journal 2020, 155, 104728 .

AMA Style

David Ribeiro, Rafael Catarino Castro, José Soares, João L.M. Santos. Photocatalytic activity of AgInS2 quantum dots upon visible light irradiation for melatonin determination through its reactive oxygen species scavenging effect. Microchemical Journal. 2020; 155 ():104728.

Chicago/Turabian Style

David Ribeiro; Rafael Catarino Castro; José Soares; João L.M. Santos. 2020. "Photocatalytic activity of AgInS2 quantum dots upon visible light irradiation for melatonin determination through its reactive oxygen species scavenging effect." Microchemical Journal 155, no. : 104728.

Original research article
Published: 09 January 2020 in Frontiers in Materials
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The success of fuel cells depends on the proper design of the electrodes and membrane allowing easy access of oxygen and protons. Using non-precious catalyst electrodes based on recyclable carbon nanostructures is most important to produce clean energy and increase the ability to commercialize the fuel cells. Herein, reduced graphene oxide (rGO) and graphene/magnetic iron oxide nanocomposite (rGO/MIO) are successfully synthesized as anode and cathode, respectively, from polyethylene terephthalate (PET) waste bottles using easy steps in order to simplify the method and reducing the production cost. While, the membrane is prepared from low cost and eco-friendly ternary polymers blend which are polyvinyl alcohol (PVA), polyethylene oxide (PEO) and polyvinyl pyrrolidone (PVP) then doped with sulfonated graphene oxide. The prepared electrodes have characteristic high porosity and their electrocatalytic performances are evaluated using three-electrode cell electrochemical studies as cyclic voltammetry and linear scan voltammetry combined with rotating disk electrode. A new assembly of the membrane between two non-precious catalyst electrodes as a single polymer electrolyte membrane fuel cell (PEMFC) was developed using a catalyst-coated membrane technique. The membrane electrode assembly (MEA) design parameters which affect its performance in hydrogen fuel cells as number of used catalyst layers (CL) or using gas diffusion layer (GDL) were evaluated in a single cell set-up with H2/O2 operation and the results revealed that the performance MEA was enhanced with using GDL more than that of MEA without GDL by 66% at a current density of 0.8 A cm−2 while the performance with double CL was better than that of the conventional single CL by 30% at a current density of 0.98 mA cm−2.

ACS Style

M. H. Gouda; Mohamed Elnouby; Andrew N. Aziz; M. ElSayed Youssef; D. M. F. Santos; Noha A. Elessawy. Green and Low-Cost Membrane Electrode Assembly for Proton Exchange Membrane Fuel Cells: Effect of Double-Layer Electrodes and Gas Diffusion Layer. Frontiers in Materials 2020, 6, 1 .

AMA Style

M. H. Gouda, Mohamed Elnouby, Andrew N. Aziz, M. ElSayed Youssef, D. M. F. Santos, Noha A. Elessawy. Green and Low-Cost Membrane Electrode Assembly for Proton Exchange Membrane Fuel Cells: Effect of Double-Layer Electrodes and Gas Diffusion Layer. Frontiers in Materials. 2020; 6 ():1.

Chicago/Turabian Style

M. H. Gouda; Mohamed Elnouby; Andrew N. Aziz; M. ElSayed Youssef; D. M. F. Santos; Noha A. Elessawy. 2020. "Green and Low-Cost Membrane Electrode Assembly for Proton Exchange Membrane Fuel Cells: Effect of Double-Layer Electrodes and Gas Diffusion Layer." Frontiers in Materials 6, no. : 1.