Person: Segura Castedo, José Luis
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First Name
José Luis
Last Name
Segura Castedo
Affiliation
Universidad Complutense de Madrid
Faculty / Institute
Ciencias Químicas
Department
Química Orgánica
Area
Química Orgánica
Identifiers
7 results
Search Results
Now showing 1 - 7 of 7
Item Robust Amide‐Linked Fluorinated Covalent Organic Framework for Long‐Term Oxygen Reduction Reaction Electrocatalysis(2024) Jiménez‐Duro, Miguel; Martínez‐Periñán, Emiliano; Martínez‐Fernández, Marcos; Martínez, José I.; Lorenzo, Encarnación; Segura Castedo, José LuisAbstractThe high energy demand of the evolving world opens the door to develop more sustainable and environmentally friendly energy sources. Oxygen reduction reaction (ORR) is a promising candidate, being the 2e− pathway of great interest for the green production of hydrogen peroxide. Metal‐free covalent organic frameworks (COFs) electrocatalysts present a suitable alternative to substitute the noble‐metals more commonly employed in this application. However, the lability of the linkages building up the framework raises an issue for their long‐term use and application in aggressive media. Herein, a stable amide‐linked COF is reported through post‐synthetic modification of a previously reported imine‐linked COF proven to be effective as an electrocatalyst, enhancing its chemical stability and electrochemical response. It is found that after the linkage transformation, the new electrocatalyst displays a higher selectivity toward the H2O2 production (98.5%) and an enhanced turnover frequency of 0.155 s−1, which is among the bests reported to date for metal‐free and COF based electrocatalysts. The results represent a promising step forward for metal‐free non pyrolyzed electrocatalysts, improving their properties through post‐synthetic linkage modification for long‐term operation.Item Scalable Synthesis and Electrocatalytic Performance of Highly Fluorinated Covalent Organic Frameworks for Oxygen Reduction(Angewandte Chemie International Edition, 2023) Martínez‐Fernández, Marcos; Martínez‐Periñán, Emiliano; Peña Ruigómez, Alejandro de la; Cabrera Trujillo, Jorge Juan; Navarro, Jorge A.R.; Aguilar‐Galindo, Fernando; Rodríguez‐San‐Miguel, David; Ramos, Mar; Vismara,Rebecca; Zamora, Félix; Lorenzo, Encarnación; Segura Castedo, José LuisIn this study, we present a novel approach for the synthesis of covalent organic frameworks (COFs) that overcomes the common limitations of non-scalable solvothermal procedures. Our method allows for the room-temperature and scalable synthesis of a highly fluorinated DFTAPB-TFTA-COF, which exhibits intrinsic hydrophobicity. We used DFT-based calculations to elucidate the role of the fluorine atoms in enhancing the crystallinity of the material through corrugation effects, resulting in maximized interlayer interactions, as disclosed both from PXRD structural resolution and theoretical simulations. We further investigated the electrocatalytic properties of this material towards the oxygen reduction reaction (ORR). Our results show that the fluorinated COF produces hydrogen peroxide selectively with low overpotential (0.062 V) and high turnover frequency (0.0757 s-1 ) without the addition of any conductive additives. These values are among the best reported for non-pyrolyzed and metal-free electrocatalysts. Finally, we employed DFT-based calculations to analyse the reaction mechanism, highlighting the crucial role of the fluorine atom in the active site assembly. Our findings shed light on the potential of fluorinated COFs as promising electrocatalysts for the ORR, as well as their potential applications in other fields.Item Scalable synthesis and electrocatalytic performance of highly fluorinated covalent organic frameworks for oxygen reduction(Angewandte Chemie International Edition, 2023) Martínez‐Fernández, Marcos; Martínez‐Periñán, Emiliano; Peña Ruigómez, Alejandro de la; Cabrera Trujillo, Jorge Juan; R. Navarro, Jorge A.; Aguilar Galindo, Fernando; Rodríguez‐San‐Miguel, David; Ramos, Mar; Vismara, Rebecca; Félix Zamora; Lorenzo, Encarnación; Segura Castedo, José LuisAbstract In this study, we present a novel approach for the synthesis of covalent organic frameworks (COFs) that overcomes the common limitations of non‐scalable solvothermal procedures. Our method allows for the room‐temperature and scalable synthesis of a highly fluorinated DFTAPB‐TFTA‐COF, which exhibits intrinsic hydrophobicity. We used DFT‐based calculations to elucidate the role of the fluorine atoms in enhancing the crystallinity of the material through corrugation effects, resulting in maximized interlayer interactions, as disclosed both from PXRD structural resolution and theoretical simulations. We further investigated the electrocatalytic properties of this material towards the oxygen reduction reaction (ORR). Our results show that the fluorinated COF produces hydrogen peroxide selectively with low overpotential (0.062 V) and high turnover frequency (0.0757 s−1) without the addition of any conductive additives. These values are among the best reported for non‐pyrolyzed and metal‐free electrocatalysts. Finally, we employed DFT‐based calculations to analyse the reaction mechanism, highlighting the crucial role of the fluorine atom in the active site assembly. Our findings shed light on the potential of fluorinated COFs as promising electrocatalysts for the ORR, as well as their potential applications in other fields.Item Electrochemical (Bio)Sensors Based on Covalent Organic Frameworks (COFs)(Sensors, 2022) Martínez-Periñán, Emiliano; Martínez-Fernández, Marcos; Segura Castedo, José Luis; Lorenzo, EncarnaciónCovalent organic frameworks (COFs) are defined as crystalline organic polymers with programmable topological architectures using properly predesigned building blocks precursors. Since the development of the first COF in 2005, many works are emerging using this kind of material for different applications, such as the development of electrochemical sensors and biosensors. COF shows superb characteristics, such as tuneable pore size and structure, permanent porosity, high surface area, thermal stability, and low density. Apart from these special properties, COF’s electrochemical behaviour can be modulated using electroactive building blocks. Furthermore, the great variety of functional groups that can be inserted in their structures makes them interesting materials to be conjugated with biological recognition elements, such as antibodies, enzymes, DNA probe, aptamer, etc. Moreover, the possibility of linking them with other special nanomaterials opens a wide range of possibilities to develop new electrochemical sensors and biosensors.Item Evaluation of the oxygen reduction reaction electrocatalytic activity of postsynthetically modified covalent organic frameworks(ACS Sustainable Chemistry & Engineering, 2023) Martínez-Fernández, Marcos; Martínez-Periñán, Emilio; Martínez, José I.; Gordo-Lozano, Marta; Zamora, Felix; Segura Castedo, José Luis; Lorenzo, EncarnaciónThe pyrolysis of organic precursors to produce heteroatomic-doped carbonaceous materials has emerged as a powerful tool to construct metal-free heterogeneous electrocatalysts due to their low cost and their environmental friendliness. However, the lack of control in the atomic positions or the location of the chemical functionalities makes it difficult to establish structure–property relationships. Herein, we report an easy strategy to compare the electrocatalytic oxygen reduction reaction (ORR) performance of metal-free and nonpyrolyzed materials by postsynthetic modification of covalent organic frameworks (COFs) via click-chemistry. This method facilitates the evaluation of different active centers using materials with the same morphology and prevents active site agglomeration by covalently anchoring these moieties inside of a porous and crystalline framework. In this study we developed a series of diimide-based materials (XDI0.17-COFs) with a loading of 7.65 × 10–4 mol of active site/mg of host COF. The bulk COFs have been delaminated to perform electrode modification by drop-casting. The electrocatalytic response toward the ORR has been studied in alkaline media obtaining the best results for the NDI0.17-COF with an onset potential of 0.77 V (vs reversible hydrogen electrode, RHE) and a limiting current of 4.2 mA/cm2 by a preferred pathway toward water electroreduction. Finally, an adequate combination of density functional theory with the thermochemical Gibbs free energy formalism has been used to theoretically rationalize the ORR mechanism in these metal-free and nonpyrolyzed materials. We have obtained theoretical ORR overpotentials for each COF system agreeing with the experimental observation, which correlate with the ability of the NDI, BzDI, and PDI molecular blocks to accommodate electrons. Our work provides a guideline on how to study the electrocatalytic performance of different organic moieties in metal-free and non-pyrolyzed COFs avoiding their de novo synthesis by using the click postsynthetic methodology.Item Electrochemical (bio)sensors based on covalent organic frameworks (COFs)(Sensors, 2022) Martínez-Periñán, Emiliano; Martínez-Fernández, Marcos; Segura Castedo, José Luis; Lorenzo, EncarnaciónCovalent organic frameworks (COFs) are defined as crystalline organic polymers with programmable topological architectures using properly predesigned building blocks precursors. Since the development of the first COF in 2005, many works are emerging using this kind of material for different applications, such as the development of electrochemical sensors and biosensors. COF shows superb characteristics, such as tuneable pore size and structure, permanent porosity, high surface area, thermal stability, and low density. Apart from these special properties, COF’s electrochemical behaviour can be modulated using electroactive building blocks. Furthermore, the great variety of functional groups that can be inserted in their structures makes them interesting materials to be conjugated with biological recognition elements, such as antibodies, enzymes, DNA probe, aptamer, etc. Moreover, the possibility of linking them with other special nanomaterials opens a wide range of possibilities to develop new electrochemical sensors and biosensors.Item Covalent organic frameworks based on electroactive naphthalenediimide as active electrocatalysts toward oxygen reduction reaction(Applied Materials Today, 2022) Martínez-Fernández, Marcos; Martínez-Periñán, Emiliano; Royuela, Sergio; Martínez, José ; Zamora, Felix; Lorenzo, Encarnación; Segura Castedo, José LuisDeveloping organic electrocatalysts toward the oxygen reduction reaction (ORR) that avoid heteroatom doping processes and high-temperature carbonization is of great significance for the maturing of fuel cell applications. Herein, a series of two-dimensional imide-based covalent organic framework (COFs) electrocatalysts toward the ORR is reported. The hydrodynamic electrochemical study reveals that 3.5 electrons are exchanged during the ORR indicating that the process catalyzed by these COFs has a clear preference for the 4-electron reduction pathway. The COFs contain conjugated electroactive napthalenediimide (NDI) moieties that provides the active sites for the electrocatalysis and promotes the formation of COFs with face-to-face π-π stacked structures to provide intrinsic porosity and large surface areas. These COFs can be essentially considered as an organized pattern of active sites embedded in the pore walls of the COF. The choice of suitable comonomers with variable distortions from planarity offers the possibility of obtaining these electroactive COFs with similar redox ability but different degrees of porosity and interlaminar spacing. This work evidences a new insight into developing novel families of electrocatalysts from COFs. Structure and stacking fashion of the COF-systems are investigated on the basis of DFT calculations, as well as the photoabsorption spectra of the representative molecular entities and a proof-of-concept rationalization of the intermediate steps of the ORR mechanism.