Examinando por Autor "Ortíz-Bustos, Josefa"

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2D/2D NiTi-LDH/BiOBr photocatalyst with extraordinary NOx removal under visible light
(Elsevier, 2023) Oliva, M.A.; Ortíz-Bustos, Josefa; Cruz-Yusta, M.; Martin, F.; del Hierro, Isabel; Pérez, Yolanda; Pavlovic, I.; Sánchez, Luis
Many current studies are focused on the development of 2D/2D nanosystems based on non-traditional semiconductors as efficient visible light-active photocatalysts, due to their interesting structural and optical properties. Thus, the charge-separation in heterostructures can be enhanced by boosting the interfacial contact. In this work, robust 2D/2D NiTi/BiOBr composites have been prepared by incorporating a 2D layered BiOBr into NiTi-layered double hydroxides (LDH) for the subsequent study of their photocatalytic action in the control of NOx pollution. The successful formation of a type-II heterojunction between both semiconductors has been confirmed by several characterization techniques (including XPS, NMR and electrochemical studies), indicating an intimate contact interface that helps enhance the visible light photocatalytic performance of NiTi-LDH. In particular, the NiTi–LDH/BiOBr–0.6 heterojunction, with a more efficient separation of photoinduced carriers, showed exceptional NO removal efficiency under visible light and remarkable robustness for the recycling process.
Enhanced adsorption–catalysis combination for the removal of sulphur from fuels using polyoxometalates supported on amphipathic hybrid mesoporous silica nanoparticles
(Royal Society of Chemistry, 2023) Ortíz-Bustos, Josefa; Pérez del Pulgar, Helena; Pérez, Yolanda; del Hierro, Isabel
Polyoxometalate (POM) mesoporous silica-based materials with a low POM loading have been designed with hydrophilic and hydrophobic properties. These materials act as powerful heterogeneous catalysts in oxidative desulfurization (ODS), owing to their ability to adsorb both H2O2 and sulphur-containing compounds from the model oil simultaneously. The formation of charge transfer salts through ion pair interaction with a choline functionality, available on the hybrid silica support, affords robust and recyclable heterogeneous catalysts for the ODS process under mild conditions (45 min and 40 °C). Besides, the nature of the polyoxometalate anions is highly dependent on the characteristics of the silica surface. The masking of silanol groups present on the silica surface using silylating agents, with diverse reactivity and steric hindrance, influences the silica surface–heteropolyanion interactions, as well as heteropolyanion–heteropolyanion interactions. In addition, it modifies the hydrophobic properties of the surface, which is a determining factor in the adsorption properties of non-polar dibenzothiophene (DBT) by the catalysts. Adsorption, an anterior step to the oxidation reaction, has been demonstrated to be key to the superior activity of POM-SiMe3-Chol-MSN, where the silanol groups have been capped by trimethylsilyl groups. For the first time, and to better understand POM–surface and POM–POM anion interactions, an extensive characterization of the materials has been performed using 13C, 31P, and 95Mo MAS NMR spectroscopy and solid-state electrochemical techniques, among others.
Structure, Stability, Electrochemical and catalytic properties of polyoxometalates 1 immobilized on choline-based hybrid mesoporous silica
(Elsevier, 2021) Ortíz-Bustos, Josefa; Pérez, Yolanda; del Hierro, Isabel
Polyoxometalate-based heterogeneous catalysts have been prepared by immobilization 12 of Keggin-type heteropolyacid on hybrid mesoporous silica nanoparticles with choline 13 hydroxide based ionic liquid. The immobilization process has been accomplished by a 14 simple acid-base reaction with phosphomolybdic acid. For comparison purposes, 15 additional supports (hybrid-SBA-15 and TiO2) have been also used in order to establish 16 the nature of the interactions between the heteropolyacid and the surface’s groups of 17 the support. To do this, electrochemical and 31P MAS-NMR studies have been carried 18 out finding the formation of moieties like (Chol)2[HPMo12O40] and/or (Chol)3[PMo12O40] 19 on the silica materials. Polyoxometalate-based heterogeneous catalysts have been 20 effectively tested for the oxidative desulfurization of DBT in model oil. Thus, complete 21 removal of sulphur (99.7 %) was achieved with polyoxometalate supported on the silica 22 after 2 h and using H2O2 as a green oxidant. Additionally, reusability and stability studies 23 of the most active catalyst have been performed.