Examinando por Autor "Royuela, Sergio"

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Oxygen Reduction Using a Metal-Free Naphthalene Diimide-Based Covalent Organic Framework Electrocatalyst
(2020) Royuela, Sergio; Martínez-Periñán, Emiliano; Arrieta, Marina P.; Martínez, José Ignacio; Ramos, M.Mar; Zamora, Félix; Lorenzo, Encarnación; Segura, José L.
A novel naphthalene diimide-based covalent organic framework (NDI-COF) has been synthesized and successfully exfoliated into COF nanosheets (CONs). Electrochemical measurements reveal that the naphthalene diimide units incorporated into NDI-CONs act as efficient electrocatalyst for oxygen reduction in alkaline media, showing its potential for the development of metal-free fuel cells.
Post-synthetic modification of covalent organic frameworks
(Royal Society of Chemistry, 2019-07-21) Ramos, Mar; Royuela, Sergio; Segura, Jose Luis
Covalent organic frameworks (COFs) are organic porous materials with many potential applications, which very often depend on the presence of chemical functionality at the organic building blocks. Functionality that cannot be introduced into COFs directly via de novo syntheses can be accessed through post-synthetic modification (PSM) strategies. Current strategies for the post-synthetic modification of COFs involve (i) incorporation of a variety of active metal species by using metal complexation through coordination chemistry, (ii) covalent bond formation between existing pendant groups and incoming constituents and (iii) chemical conversion of linkages. (iv) The post-synthetic modification is sometimes assisted by a monomer truncation strategy for the internal functionalization of COFs. (v) Even more intriguing methods that go beyond PSM are herein termed building block exchange (BBE) which encompasses framework-to-framework transformations taking advantage of the fact that reversible bond formation is a characteristic feature of COFs. This strategy allows the use of protoCOF structures (i.e., the utilization of a parent COF as a template) for the evolution of new COF structures with completely new components. © 2019 The Royal Society of Chemistry
Synergistic Effect of Covalent Bonding and Physical Encapsulation of Sulfur in the Pores of a Microporous COF to Improve Cycling Performance in Li-S Batteries
(Wiley-VCH Verlag, 2019) Royuela, Sergio; Almarza, J; Mancheño, MJ; Pérez-Flores, JC; Michel, EG; Ramos, MM; Zamora, F; Occon, P; Segura JL
Lithium-sulfur batteries stands out as a promising technology for energy storage owing to a combination of favorable characteristics including a high theoretical gravimetric capacity, energy density, inexpensive character, and environmental benignity. Covalent organic frameworks (COFs) are a rapidly developing family of functional nanostructures which combine porosity and crystallinity, and which have been already used in these kinds of batteries to build sulfur electrodes, by embedding sulfur into porous COFs in order to enhance cycle lifetimes. In this contribution, this is taken one step forward and a COF endowed with vinyl groups is used, in order to graft sulfur to the COF skeleton through inverse vulcanization. The main aim of the article is to show the synergistic effect of covalent bonding and physical encapsulation of sulfur in the pores of the COF in order to alleviate the fatal redox shuttling process, to improve the cycling performance, and to provide faster ion diffusion pathways. In addition, it is shown how the material with covalently-bound S provides better electrochemical performance under demanding and/or changeable charge conditions than a parent analogue material with sulfur physically confined, but without covalent linkage
Uracil grafted imine-based covalent organic framework for nucleobase recognition
(Royal Soc Chemistry, 2018) Royuela, Sergio; García-Garrido, Eduardo; Martín Arroyo, Miguel; Mancheño, María José; Ramos, Maria M; Gonzalez Rodríguez, David; Somoza, Alvaro; Zamora, Félix; Segura, José Luis
An imine-based covalent organic framework (COF) decorated in its cavities with uracil groups has shown selective recognition towards adenine in water. These results show how the confinement of the base-pair inside the COF’s pores allows a remarkable selective recognition in aqueous media.