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Piñeiro-García, Alexis
Publications (10 of 12) Show all publications
Rafei, M., Piñeiro-García, A., Wu, X., Perivoliotis, D. K., Wågberg, T. & Gracia-Espino, E. (2024). Hydrogen evolution mediated by sulfur vacancies and substitutional Mn in few-layered molybdenum disulfide. Materials Today Energy, 41, Article ID 101524.
Open this publication in new window or tab >>Hydrogen evolution mediated by sulfur vacancies and substitutional Mn in few-layered molybdenum disulfide
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2024 (English)In: Materials Today Energy, ISSN 2468-6069, Vol. 41, article id 101524Article in journal (Refereed) Published
Abstract [en]

MoS2 is widely praised as a promising replacement for Pt as an electrocatalyst for the hydrogen evolution reaction (HER), but even today, it still suffers from low performance. This issue is tackled by using Mn3+ as a surface modifier to trigger sulfur vacancy formation and enhance electron transport in few-layered 2H MoS2. Only 10% of Mn is sufficient to transform the semiconductive MoS2 into an active HER electrocatalyst. The insertion of Mn reduces both HER onset potential and Tafel slope which allows reaching 100 mA/cm2 at an overpotential of 206 mV, ten times larger of what undoped MoS2 can achieve. The enhanced activity arises because Mn3+ introduces electronic states near the conduction band, promotes sulfur vacancies, and increases the hydrogen adsorption. In addition to its facile production and extended shelf-life, Mn–MoS2 exhibits an efficiency of 73% at 800 mA/cm2 and 2.0 V when used in proton exchange membrane water electrolyzers.

Place, publisher, year, edition, pages
Elsevier, 2024
Keywords
Hydrogen evolution reaction, Manganese, Proton exchange membrane, Sulfur vacancy, Water electrolysis
National Category
Materials Chemistry Other Physics Topics
Identifiers
urn:nbn:se:umu:diva-221781 (URN)10.1016/j.mtener.2024.101524 (DOI)2-s2.0-85185894201 (Scopus ID)
Funder
Swedish Research Council, 2018-03937The Kempe Foundations, JCK-2132The Kempe Foundations, JCK-2021Carl Tryggers foundation , CTS 21-1581Swedish Foundation for Strategic ResearchSwedish National Infrastructure for Computing (SNIC)
Available from: 2024-03-19 Created: 2024-03-19 Last updated: 2024-03-19Bibliographically approved
Piñeiro-García, A., Wu, X., Rafei, M., Mörk, P. J. & Gracia-Espino, E. (2023). A Quaternary mixed oxide protective scaffold for ruthenium during oxygen evolution reaction in acidic media. Communications Engineering, 2(1), Article ID 28.
Open this publication in new window or tab >>A Quaternary mixed oxide protective scaffold for ruthenium during oxygen evolution reaction in acidic media
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2023 (English)In: Communications Engineering, E-ISSN 2731-3395, Vol. 2, no 1, article id 28Article in journal, Editorial material (Refereed) Published
Abstract [en]

Proton exchange membrane water electrolysis is widely used in hydrogen production, but its application is limited by significant electrocatalyst dissolution at the anode during the oxygen evolution reaction (OER). The best performing electrocatalysts to date are based on ruthenium and iridium oxides, but these experience degradation even at moderate cell potentials. Here we investigate a quaternary Sn-Sb-Mo-W mixed oxide as a protective scaffold for ruthenium oxide. The acid-stable mixed oxide consists of an interconnected network of nanostructured oxides capable of stabilizing ruthenium into the matrix (Ru-MO). In combination with titanium fibre felt, we observed a lower degradation in the oxygen evolution reaction activity compared to unprotected ruthenium oxide after the electrochemical stress test. The superior stability of Ru-MO@Ti is attributed to the presence of MO which hinders the formation of reactive higher valence ruthenium (Ru+8). Our work demonstrates the potential of multi-metal oxides to extend the lifetime of the OER active metal and the titanium support.

Place, publisher, year, edition, pages
Springer Nature, 2023
National Category
Materials Chemistry
Research subject
Materials Science
Identifiers
urn:nbn:se:umu:diva-215473 (URN)10.1038/s44172-023-00080-5 (DOI)
Funder
Swedish Research Council, 2018-03937The Kempe Foundations, JCK-2132Carl Tryggers foundation , CTS 21-1581Swedish Research Council, 2018-03937The Kempe Foundations, JCK-2132Carl Tryggers foundation , CTS 21-1581Swedish Research Council, 2018-03937The Kempe Foundations, JCK-2132Carl Tryggers foundation , CTS 21-1581
Available from: 2023-10-19 Created: 2023-10-19 Last updated: 2024-02-26Bibliographically approved
Piñeiro-García, A., Perivoliotis, D. K., Wu, X. & Gracia-Espino, E. (2023). Benchmarking molybdenum-based materials as cathode electrocatalysts for proton exchange membrane water electrolysis: can these compete with Pt?. ACS Sustainable Chemistry and Engineering, 11(20), 7641-7654
Open this publication in new window or tab >>Benchmarking molybdenum-based materials as cathode electrocatalysts for proton exchange membrane water electrolysis: can these compete with Pt?
2023 (English)In: ACS Sustainable Chemistry and Engineering, E-ISSN 2168-0485, Vol. 11, no 20, p. 7641-7654Article in journal (Refereed) Published
Abstract [en]

Proton exchange membrane water electrolysis (PEMWE) is a promising technology to produce high-purity renewable hydrogen gas. However, its operation efficiency is highly dependent on the usage of expensive noble metals as electrocatalysts. Replacing, decreasing, or simply extending the operational lifetime of these precious metals have a positive impact on the hydrogen economy. Mo-based electrocatalysts are often praised as potential materials to replace the Pt used at the cathode to catalyse the hydrogen evolution reaction (HER). Most electrocatalytic studies are performed in traditional three-electrode cells with different operational conditions than those seen in PEM systems, making it difficult to predict the expected material’s performance under industrially relevant conditions. Therefore, we investigated the viability of using three selected Mo-based nanomaterials (1T′-MoS2, Co-MoS2, and β-Mo2C) as HER electrocatalysts in PEMWE systems. We investigated the effects of replacing Pt on the catalyst loading, charge transfer resistance, kinetics, operational stability, and hydrogen production efficiency during the PEMWE operation. In addition, we developed a methodology to identify the individual contribution of the anode and cathode kinetics in a PEMWE system, allowing to detect the cause behind the performance drop when using Mo-based electrocatalysts. Our results indicate that the electrochemical performance in three-electrode cells might not strictly predict the performance that could be achieved in PEMWE cells due to differences in interfaces and porosity of the macroscopic catalyst layers. Among the catalysts studied, 1T′-MoS2 is truly an excellent candidate to replace Pt as an HER electrocatalyst due to its low overpotential, low charge transfer resistance, and excellent durability, reaching a high efficiency of ∼75% at 1 A cm-2 and 1.94 V. Our study highlights the importance of a continuous development of efficient noble-metal free HER electrocatalysts suitable for PEMWE systems.

Place, publisher, year, edition, pages
American Chemical Society (ACS), 2023
Keywords
carbide, cobalt, electrolyser, molybdenum, proton exchange membrane, sulfide, water splitting
National Category
Other Chemical Engineering
Identifiers
urn:nbn:se:umu:diva-209305 (URN)10.1021/acssuschemeng.2c07201 (DOI)000984386300001 ()2-s2.0-85159600021 (Scopus ID)
Funder
Swedish Research Council, 2018-03937The Kempe Foundations, JCK-2132The Kempe Foundations, JCK-2021Carl Tryggers foundation , 21-1581
Available from: 2023-06-08 Created: 2023-06-08 Last updated: 2024-02-26Bibliographically approved
Kagkoura, A., Karamoschos, N., Perivoliotis, D. K., Piñeiro-García, A., Gracia-Espino, E., Tasis, D. & Tagmatarchis, N. (2023). Bifunctional nanostructured palladium/MoSx electrocatalyst for cathode hydrogen evolution reaction PEM water electrolysis and oxygen reduction reaction. Advanced Sustainable Systems, 7(5), Article ID 2200518.
Open this publication in new window or tab >>Bifunctional nanostructured palladium/MoSx electrocatalyst for cathode hydrogen evolution reaction PEM water electrolysis and oxygen reduction reaction
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2023 (English)In: Advanced Sustainable Systems, E-ISSN 2366-7486, Vol. 7, no 5, article id 2200518Article in journal (Refereed) Published
Abstract [en]

The creation of effective Pd-based architectures with numerous electrocatalytic active sites and efficient charge transfer is of key importance for improving the electrocatalytic performance in water electrolyzer and fuel cell applications. On the other hand, MoS2, possessing multiple electrocatalytic active sites, can act both as support and booster to Pd-based electrocatalytic structures. Herein, MoSx@Pd hybrids were successfully synthesized by using a one-pot liquid phase solvothermal strategy with stoichiometric excess of Pd. The optimized MoSx@Pd proves to be an excellent bifunctional electrocatalyst for both hydrogen evolution reaction and oxygen reduction reaction (ORR). Optimized MoSx@Pd operates the process for hydrogen evolution at the same potential as Pt/C and achieves a low overpotential of 76 mV at −10 mA cm−2 due to improved reaction kinetics and charge transfer processes between Pd and MoS2. On top of that, MoSx@Pd exhibits excellent performance and stability as cathode electrocatalyst in a polymer electrolyte membrane water electrolyzer. Simultaneously, the bifunctional electrocatalyst shows enhanced electrocatalytic ORR activity and stability by maintaining 93% of its initial activity outperforming commercial Pt/C. Finally, rotating ring disk electrode analysis reveals that ORR proceeds through the energy efficient 4e− pathway, with water being the main product, rendering MoSx@Pd a promising component for fuel cells.

Place, publisher, year, edition, pages
Wiley-VCH Verlagsgesellschaft, 2023
Keywords
electrocatalyst, hydrogen evolution reaction, oxygen reduction reaction, polymer electrolyte membranes, transition metal dichalcogenides, water electrolysis
National Category
Physical Chemistry
Identifiers
urn:nbn:se:umu:diva-204762 (URN)10.1002/adsu.202200518 (DOI)000921356300001 ()2-s2.0-85147315186 (Scopus ID)
Funder
Swedish Research Council, 2018-03937The Kempe Foundations, JCK-2132The Kempe Foundations, JCK-2021Carl Tryggers foundation , CTS 21–1581
Available from: 2023-02-21 Created: 2023-02-21 Last updated: 2023-06-19Bibliographically approved
Wu, X., Piñeiro-García, A., Rafei, M., Boulanger, N., Canto-Aguilar, E. J. & Gracia-Espino, E. (2023). Scalable production of foam-like nickel-molybdenum coatings via plasma spraying as bifunctional electrocatalysts for water splitting. Physical Chemistry, Chemical Physics - PCCP, 25(31), 20794-20807
Open this publication in new window or tab >>Scalable production of foam-like nickel-molybdenum coatings via plasma spraying as bifunctional electrocatalysts for water splitting
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2023 (English)In: Physical Chemistry, Chemical Physics - PCCP, ISSN 1463-9076, E-ISSN 1463-9084, Vol. 25, no 31, p. 20794-20807Article in journal (Refereed) Published
Abstract [en]

Foam-like NiMo coatings were produced from an inexpensive mixture of Ni, Al, and Mo powders via atmospheric plasma spraying. The coatings were deposited onto stainless-steel meshes forming a highly porous network mainly composed of nanostructured Ni and highly active Ni4Mo. High material loading (200 mg cm−2) with large surface area (1769 cm2 per cm2) was achieved without compromising the foam-like characteristics. The coatings exhibited excellent activity towards both hydrogen evolution (HER) and oxygen evolution (OER) reactions in alkaline media. The HER active coating required an overpotential of 42 mV to reach a current density of −50 mA cm−2 with minimum degradation after a 24 h chronoamperometry test at −10 mA cm−2. Theoretical simulations showed that several crystal surfaces of Ni4Mo exhibit near optimum hydrogen adsorption energies and improved water dissociation that benefit the HER activity. The OER active coating also consisting of nanostructured Ni and Ni4Mo required only 310 mV to achieve a current density of 50 mA cm−2. The OER activity was maintained even after 48 h of continuous operation. We envisage that the development of scalable production techniques for Ni4Mo alloys will greatly benefit its usage in commercial alkaline water electrolysers.

Place, publisher, year, edition, pages
Royal Society of Chemistry, 2023
National Category
Other Chemical Engineering Physical Chemistry
Identifiers
urn:nbn:se:umu:diva-212732 (URN)10.1039/d3cp01444d (DOI)001031244900001 ()37465860 (PubMedID)2-s2.0-85166241263 (Scopus ID)
Funder
Swedish Research Council, 2018-03937The Kempe Foundations, JCK-2132Carl Tryggers foundation , CTS 21-1581Swedish Research Council, 2022-06725Swedish Research Council, 2018-05973
Available from: 2023-08-16 Created: 2023-08-16 Last updated: 2024-02-26Bibliographically approved
Piñeiro-García, A. & Semetey, V. (2023). The "how" and "where" behind the functionalization of graphene oxide by thiol-ene "click" chemistry. Chemistry - A European Journal, 29(50), Article ID e202301604.
Open this publication in new window or tab >>The "how" and "where" behind the functionalization of graphene oxide by thiol-ene "click" chemistry
2023 (English)In: Chemistry - A European Journal, ISSN 0947-6539, E-ISSN 1521-3765, Vol. 29, no 50, article id e202301604Article, review/survey (Refereed) Published
Abstract [en]

Graphene oxide (GO) is a 2D nanomaterial with unique chemistry due to the combination of sp2 hybridization and oxygen functional groups (OFGs) even in single layer. OFGs play a fundamental role in the chemical functionalization of GO to produce GO-based materials for diverse applications. However, traditional strategies that employ epoxides, alcohols, and carboxylic acids suffer from low control and undesirable side reactions, including by-product formation and GO reduction. Thiol-ene “click” reaction offers a promising and versatile chemical approach for the alkene functionalization (−C=C−) of GO, providing orthogonality, stereoselectivity, regioselectivity, and high yields while reducing by-products. This review examines the chemical functionalization of GO via thiol-ene “click” reactions, providing insights into the underlying reaction mechanisms, including the role of radical or base catalysts in triggering the reaction. We discuss the “how” and “where” the reaction takes place on GO, the strategies to avoid unwanted side reactions, such as GO reduction and by-product formation. We anticipate that multi-functionalization of GO via the alkene groups will enhance GO physicochemical properties while preserving its intrinsic chemistry.

Place, publisher, year, edition, pages
John Wiley & Sons, 2023
Keywords
graphene oxide, photo-initiated thiol-ene, thermal-initiated thiol-ene, thiol-ene click chemistry, thiol-ene Michael addition
National Category
Organic Chemistry
Identifiers
urn:nbn:se:umu:diva-212815 (URN)10.1002/chem.202301604 (DOI)001043150500001 ()37367388 (PubMedID)2-s2.0-85166915062 (Scopus ID)
Funder
The Kempe Foundations, JCK-2132The Kempe Foundations, JCK-2021
Available from: 2023-08-16 Created: 2023-08-16 Last updated: 2024-01-08Bibliographically approved
Piñeiro-García, A., Vega-Díaz, S. M., Tristan, F., Meneses-Rodríguez, D. & Semetey, V. (2022). Functionalization and soft photoreduction of graphene oxide triggered by the photoinitiator during thiol-ene radical addition. FlatChem, 33, Article ID 100349.
Open this publication in new window or tab >>Functionalization and soft photoreduction of graphene oxide triggered by the photoinitiator during thiol-ene radical addition
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2022 (English)In: FlatChem, E-ISSN 2452-2627, Vol. 33, article id 100349Article in journal (Refereed) Published
Abstract [en]

Thiol-ene radical addition (TERA) is a powerful reaction for the chemical functionalization of the reactive alkenes of GO with thiols. To trigger TERA, a photoinitiator (PI) is added to ensure high yields associated with fast conversion rates. However, the inappropriate use of PIs might affect the GO functionalization leading to photoreduction as well as low conversion rates. Herein, we explored the GO functionalization with cysteamine (CA) by TERA and its reduction influenced by Irgacure® 369, a commercial PI. We focused to analyze the reaction conditions that promote an orthogonal GO functionalization finding the limits where the photoreduction began. UV-spectroscopy, Raman spectroscopy, fluorescence labeling and XPS were used to characterize the functionalized GO. The data indicate three possible scenarios depending on the PI/CA molar ratio: i) orthogonal GO functionalization by TERA, ii) side reactions between GO and the radicals formed upon the PI photocleavage, and iii) soft photoreduction of the GO with alcohols and carboxylic acids as the functional groups mainly affected. However, we found that the GO functionalization by TERA was still occurring, but in less favorable conditions despite the side reactions and by-products. Therefore, photo-initiated TERA was confirmed as a powerful reaction to functionalize the reactive alkenes of GO, and by tuning the PI/CA molar ratio an orthogonal GO functionalization can be achieved, limiting side reactions and particularly GO reduction.

Place, publisher, year, edition, pages
Elsevier, 2022
Keywords
GO functionalization, Photoreduction, Radicals, Side-reactions, Thiol-ene radical addition
National Category
Organic Chemistry
Identifiers
urn:nbn:se:umu:diva-193057 (URN)10.1016/j.flatc.2022.100349 (DOI)000772600700001 ()2-s2.0-85125775185 (Scopus ID)
Available from: 2022-03-21 Created: 2022-03-21 Last updated: 2023-09-05Bibliographically approved
Rafei, M., Wu, X., Piñeiro-García, A., Miranda la Hera, V., Wågberg, T. & Gracia-Espino, E. (2022). Non-stoichiometric NiFeMo solid solutions; tuning the hydrogen adsorption energy via molybdenum incorporation. Advanced Materials Interfaces, 9(34), Article ID 2201214.
Open this publication in new window or tab >>Non-stoichiometric NiFeMo solid solutions; tuning the hydrogen adsorption energy via molybdenum incorporation
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2022 (English)In: Advanced Materials Interfaces, ISSN 2196-7350, Vol. 9, no 34, article id 2201214Article in journal (Refereed) Published
Abstract [en]

Solution precursor plasma spraying is used to produce catalytic trimetallic coatings containing Ni, Fe and Mo directly onto stainless-steel mesh, Ni foam and carbon paper. The resulting material is mostly comprised of face centered cubic FeNi3 alloy forming a highly porous coating with nanostructured features. The addition of Mo (up to ≈14 at%) generates no new crystal phases but only an increase in the lattice parameter, indicating the formation of FeNi3Mox solid solutions. The FeNi3Mox solid solutions are used as electrocatalyst for the hydrogen evolution reaction (HER) in alkaline media. The addition of Mo increases the HER activity significantly reaching an optimum performance at ≈9 at% Mo (FeNi3Mo0.40) with an overpotential at −10 mA cm−2 of 112 mV and a Tafel slope of 109 mV dec−1. The enhanced HER activity is attributed to the formation of a FeNi3Mox solid solution with an increased work function that is correlated to smaller hydrogen adsorption energies. Theoretical activity maps reveal that sites near superficial Mo atoms forms catalytic hot spots and are responsible for the observed activity.

Place, publisher, year, edition, pages
John Wiley & Sons, 2022
Keywords
catalytic activity maps, electrocatalysis, hydrogen evolution, NiFeMo, solid solution, ternary alloy, work function
National Category
Condensed Matter Physics Physical Chemistry
Identifiers
urn:nbn:se:umu:diva-200394 (URN)10.1002/admi.202201214 (DOI)000864415500001 ()2-s2.0-85139435922 (Scopus ID)
Available from: 2022-10-25 Created: 2022-10-25 Last updated: 2022-12-30Bibliographically approved
Botella, R., Piñeiro-García, A., Semetey, V. & Lefèvre, G. (2022). Polarized ATR-IR spectroscopy for the identification of material structure: The case of graphene oxide. Materials letters (General ed.), 320, Article ID 132352.
Open this publication in new window or tab >>Polarized ATR-IR spectroscopy for the identification of material structure: The case of graphene oxide
2022 (English)In: Materials letters (General ed.), ISSN 0167-577X, E-ISSN 1873-4979, Vol. 320, article id 132352Article in journal (Refereed) Published
Abstract [en]

Graphene oxide (GO) is a layered structure similar to graphite, whose planes of carbon atoms are decorated by oxygen-containing groups. These groups bring hydrophilicity and reactivity to GO, as they are present on its basal plane or at the edges. Thus, their identification is essential to determine the chemical properties of GO. Amongst the possible analytical techniques, infrared spectroscopy is suitable to identify these groups. In this work, an advanced spectroscopic method, polarized attenuated total reflectance infrared spectroscopy, was used to obtain a more in-depth analysis of these reactive groups. This new approach has allowed to refine the description of the functional groups at the surface and could be used to follow the evolution surface processes in material chemistry (e.g. grafting reactions).

Place, publisher, year, edition, pages
Elsevier, 2022
Keywords
Carbon materials, Oxidation, Spectroscopy, Thin films
National Category
Condensed Matter Physics
Identifiers
urn:nbn:se:umu:diva-194902 (URN)10.1016/j.matlet.2022.132352 (DOI)000830205800008 ()2-s2.0-85129281849 (Scopus ID)
Available from: 2022-06-01 Created: 2022-06-01 Last updated: 2023-09-05Bibliographically approved
Piñeiro-García, A., Tristan, F., Meneses-Rodríguez, D., Semetey, V. & Vega-Díaz, S. (2021). Tuning the nucleophilic attack and the reductive action of glycine on graphene oxide under basic medium. Materials Today Chemistry, 19, Article ID 100386.
Open this publication in new window or tab >>Tuning the nucleophilic attack and the reductive action of glycine on graphene oxide under basic medium
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2021 (English)In: Materials Today Chemistry, E-ISSN 2468-5194, Vol. 19, article id 100386Article in journal (Refereed) Published
Abstract [en]

Amino acids are important compounds for GO functionalization because they can improve GO properties for many applications ranging from biomedicine to depollution. However, amino acids can act as nucleophiles or as reducing agents for GO functionalization or reduction, respectively. Hence, we systematically studied the GO functionalization/reduction using glycine as a model amino acid under basic conditions at room temperature. Attenuated total reflectance–Fourier transform infrared (ATR-FTIR), X-ray photoelectron spectroscopy, and Raman spectroscopy were used to characterize the modified GO with glycine. We found that low glycine concentrations produced an epoxide ring opening reaction, whereas an increase in glycine concentration led to GO reduction. The basic medium allowed to conserve the carboxylic acid groups, whereas the GO reduction mechanism was governed by the partial hydrolysis of epoxide groups and the subsequent reduction of carboxylic acids to carbonyls. This article opens up the opportunity to study and control the conditions in which different amino acids could be used for either GO functionalization or GO reduction.

Place, publisher, year, edition, pages
Elsevier, 2021
Keywords
Dual behavior, Functionalization, Reduction, Governed by concentration
National Category
Materials Chemistry
Identifiers
urn:nbn:se:umu:diva-192622 (URN)10.1016/j.mtchem.2020.100386 (DOI)000617886300002 ()2-s2.0-85097072163 (Scopus ID)
Available from: 2022-02-20 Created: 2022-02-20 Last updated: 2024-02-12Bibliographically approved
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