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1. Interplay between alkali-metal cations and silanol sites in nanosized CHA zeolite and implications for CO2 adsorption

Author

Sajjad Ghojavand, Eddy Dib, Jérôme Rey, Ayoub Daouli, Edwin B. Clatworthy, Philippe Bazin, Valérie Ruaux, Michael Badawi, and Svetlana Mintova

Subjects
Chemistry, QD1-999
Abstract

Abstract Silanols are key players in the application performance of zeolites, yet, their localization and hydrogen bonding strength need more studies. The effects of post-synthetic ion exchange on nanosized chabazite (CHA), focusing on the formation of silanols, were studied. The significant alteration of the silanols of the chabazite nanozeolite upon ion exchange and their effect on the CO2 adsorption capacity was revealed by solid-state nuclear magnetic resonance (NMR), Fourier-transform infrared (FTIR) spectroscopy, and periodic density functional theory (DFT) calculations. Both theoretical and experimental results revealed changing the ratio of extra-framework cations in CHA zeolites changes the population of silanols; decreasing the Cs+/K+ ratio creates more silanols. Upon adsorption of CO2, the distribution and strength of the silanols also changed with increased hydrogen bonding, thus revealing an interaction of silanols with CO2 molecules. To the best of our knowledge, this is the first evidence of the interplay between alkali-metal cations and silanols in nanosized CHA.

Published
2023
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5. Methane-to-chemicals: a pathway to decarbonization

Author

Nikolai Nesterenko, Izabel C Medeiros-Costa, Edwin B Clatworthy, Hugo Cruchade, Stanislav V Konnov, Jean-Pierre Dath, Jean-Pierre Gilson, and Svetlana Mintova

Subjects
Multidisciplinary
Abstract

The utilization of methane for chemical production, often considered as the future of petrochemistry, historically could not compete economically with conventional processes due to higher investment costs. Achieving sustainability and decarbonization of the downstream industry by integration with a methane-to-chemicals process may provide an opportunity to unlock the future for these technologies. Gas-to-chemicals is an efficient tool to boost the decarbonization potential of renewable energy. While the current implementation of carbon capture utilization and storage (CCUS) technologies is of great importance for industrial decarbonization, a shift to greener CO2-free processes and CO2 utilization from external sources for manufacturing valuable goods is highly preferred. This review outlines potential options for how a methane-to-chemicals process could support decarbonization of the downstream industry.

Published
2023
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7. Direct synthesis of nanosized CHA zeolite free of organic template by a combination of cations as structure directing agents

Author

Maxime Debost, Edwin B. Clatworthy, Julien Grand, Nicolas Barrier, Nikolai Nesterenko, Jean-Pierre Gilson, Philippe Boullay, Svetlana Mintova, Laboratoire catalyse et spectrochimie (LCS), Université de Caen Normandie (UNICAEN), Normandie Université (NU)-Normandie Université (NU)-École Nationale Supérieure d'Ingénieurs de Caen (ENSICAEN), Normandie Université (NU)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS), Laboratoire de cristallographie et sciences des matériaux (CRISMAT), Normandie Université (NU)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche sur les Matériaux Avancés (IRMA), Normandie Université (NU)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Rouen Normandie (UNIROUEN), Normandie Université (NU)-Institut national des sciences appliquées Rouen Normandie (INSA Rouen Normandie), Institut National des Sciences Appliquées (INSA)-Normandie Université (NU)-Institut National des Sciences Appliquées (INSA)-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Rouen Normandie (UNIROUEN), Institut National des Sciences Appliquées (INSA)-Normandie Université (NU)-Institut National des Sciences Appliquées (INSA)-Centre National de la Recherche Scientifique (CNRS), and TotalEnergies OneTech Belgium

Subjects
Mechanics of Materials, [CHIM]Chemical Sciences, General Materials Science, General Chemistry, Condensed Matter Physics
Abstract

International audience

Published
2022
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8. Synthesis of Discrete CHA Zeolite Nanocrystals without Organic Templates for Selective CO 2 Capture

Author

Maxime Debost, Fabien Laine, Paul Benjamin Klar, Philippe Boullay, Julien Grand, Svetlana Mintova, Nicolas Barrier, Nikolai Nesterenko, Lukáš Palatinus, Petr Brázda, Edwin B. Clatworthy, Laboratoire de cristallographie et sciences des matériaux (CRISMAT), Université de Caen Normandie (UNICAEN), Normandie Université (NU)-Normandie Université (NU)-École Nationale Supérieure d'Ingénieurs de Caen (ENSICAEN), Normandie Université (NU)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche sur les Matériaux Avancés (IRMA), Normandie Université (NU)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Rouen Normandie (UNIROUEN), Normandie Université (NU)-Institut national des sciences appliquées Rouen Normandie (INSA Rouen Normandie), Institut National des Sciences Appliquées (INSA)-Normandie Université (NU)-Institut National des Sciences Appliquées (INSA)-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Rouen Normandie (UNIROUEN), Institut National des Sciences Appliquées (INSA)-Normandie Université (NU)-Institut National des Sciences Appliquées (INSA)-Centre National de la Recherche Scientifique (CNRS), Laboratoire catalyse et spectrochimie (LCS), Normandie Université (NU)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS), Institute of Physics of the Czech Academy of Sciences (FZU / CAS), Czech Academy of Sciences [Prague] (CAS), Total Research and Technology Feluy ( [TRTF]), Normandie Université (NU)-Centre National de la Recherche Scientifique (CNRS), École Nationale Supérieure d'Ingénieurs de Caen (ENSICAEN), Normandie Université (NU)-Normandie Université (NU)-Centre National de la Recherche Scientifique (CNRS)-Université de Caen Normandie (UNICAEN), Normandie Université (NU)-Institut de Chimie du CNRS (INC), Centre National de la Recherche Scientifique (CNRS)-École Nationale Supérieure d'Ingénieurs de Caen (ENSICAEN), Normandie Université (NU)-Normandie Université (NU)-Institut de Chimie du CNRS (INC)-Université de Caen Normandie (UNICAEN), and Normandie Université (NU)

Subjects
Chabazite, Materials science, education, 02 engineering and technology, Template-free synthesis, 010402 general chemistry, 01 natural sciences, 7. Clean energy, Catalysis, Colloid, Adsorption, Aluminosilicate, [CHIM]Chemical Sciences, Molecule, Zeolite, ComputingMilieux_MISCELLANEOUS, Precession-assisted 3D ED, 010405 organic chemistry, Sorption, General Chemistry, General Medicine, 021001 nanoscience & nanotechnology, 0104 chemical sciences, Chemical engineering, Nanocrystal, [PHYS.COND.CM-MS]Physics [physics]/Condensed Matter [cond-mat]/Materials Science [cond-mat.mtrl-sci], In situ PXRD, Nanozeolites, CO2 adsorption, 0210 nano-technology
Abstract

International audience; Small-pore zeolites such as chabazite (CHA) are excellent candidates for the selective separation of CO2; however, the current synthesis involves several steps and the use of organic structure-directing agent (OSDA), increasing their cost and energy requirements. We report the synthesis of small-pore zeolite crystals (aluminosilicate) with CHA-type framework structure by direct synthesis in a colloidal suspension containing a mixture of inorganic cations only (Na+, K+, and Cs+). The location of CO2 molecules in the host structure was revealed by 3D electron diffraction (3D ED). The high sorption capacity for CO2 (3.8 mmol g−1 at 121 kPa), structural stability and regenerability of the discreate CHA zeolite nanocrystals is maintained for 10 consecutive cycles without any visible degradation. The CHA zeolite (Si:Al=2) reaches an almost perfect CO2 storage capacity (8 CO2 per unit cell) and high selectivity (no CH4 was adsorbed).

Published
2020
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9. Emphasis on the Properties of Metal‐Containing Zeolites Operating Outside the Comfort Zone of Current Heterogeneous Catalytic Reactions

Author

Nikolai Nesterenko, Svetlana Mintova, Florent Dubray, Jean-Pierre Gilson, Stanislav V. Konnov, Edwin B. Clatworthy, Laboratoire catalyse et spectrochimie (LCS), Centre National de la Recherche Scientifique (CNRS)-École Nationale Supérieure d'Ingénieurs de Caen (ENSICAEN), Normandie Université (NU)-Normandie Université (NU)-Institut de Chimie du CNRS (INC)-Université de Caen Normandie (UNICAEN), and Normandie Université (NU)

Subjects
Materials science, Biomass, 02 engineering and technology, 010402 general chemistry, 01 natural sciences, 7. Clean energy, Catalysis, Metal, Zeolite, Reaction conditions, Alkane, chemistry.chemical_classification, 010405 organic chemistry, business.industry, General Chemistry, [CHIM.MATE]Chemical Sciences/Material chemistry, [CHIM.CATA]Chemical Sciences/Catalysis, General Medicine, 021001 nanoscience & nanotechnology, Renewable energy, 0104 chemical sciences, chemistry, Chemical engineering, visual_art, visual_art.visual_art_medium, Current (fluid), business, 0210 nano-technology
Abstract

International audience; The development of catalysts that can operate under exceptionally harsh and unconventional conditions is of critical importance for the transition of the energy and chemicals industries to low-emission and renewable chemical feedstocks. In this review we will highlight materials and more specifically metal-containing zeolite catalysts that have been tested under harsh reaction conditions such as high temperature light alkane conversion and biomass valorization. Particular attention will be given to studies that explore the stability and recyclability of metal-containing zeolite catalysts operating in continuous modes. Metal-containing zeolites are considered as an important class of catalysts operating outside the comfort zone of current heterogeneous catalytic reactions in both gas and liquid phase reactions. The relationship between the properties of the metalcontaining zeolite and catalytic performance will be explored.

Published
2020
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10. Novel Strategy for the Synthesis of Ultra‐Stable Single‐Site Mo‐ZSM‐5 Zeolite Nanocrystals

Author

Svetlana Mintova, Jean-Pierre Dath, Delphine Minoux, Valentin Valtchev, Cassandre Kouvatas, Siddardha Koneti, Edwin B. Clatworthy, Cindy Aquino, Florent Dubray, Jean-Pierre Gilson, Nikolai Nesterenko, Simona Moldovan, Stanislav V. Konnov, Laboratoire catalyse et spectrochimie (LCS), Centre National de la Recherche Scientifique (CNRS)-École Nationale Supérieure d'Ingénieurs de Caen (ENSICAEN), Normandie Université (NU)-Normandie Université (NU)-Institut de Chimie du CNRS (INC)-Université de Caen Normandie (UNICAEN), Normandie Université (NU), Groupe de physique des matériaux (GPM), Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences appliquées Rouen Normandie (INSA Rouen Normandie), Institut National des Sciences Appliquées (INSA)-Normandie Université (NU)-Institut National des Sciences Appliquées (INSA)-Normandie Université (NU)-Université de Rouen Normandie (UNIROUEN), Université de Caen Normandie (UNICAEN), Normandie Université (NU)-Normandie Université (NU)-École Nationale Supérieure d'Ingénieurs de Caen (ENSICAEN), Normandie Université (NU)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS), Total Research and Technology Feluy ( [TRTF]), Université de Rouen Normandie (UNIROUEN), Normandie Université (NU)-Normandie Université (NU)-Institut national des sciences appliquées Rouen Normandie (INSA Rouen Normandie), Institut National des Sciences Appliquées (INSA)-Normandie Université (NU)-Institut National des Sciences Appliquées (INSA)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche sur les Matériaux Avancés (IRMA), Normandie Université (NU)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Rouen Normandie (UNIROUEN), Normandie Université (NU)-Institut national des sciences appliquées Rouen Normandie (INSA Rouen Normandie), Institut National des Sciences Appliquées (INSA)-Normandie Université (NU)-Institut National des Sciences Appliquées (INSA)-Centre National de la Recherche Scientifique (CNRS)-Université de Caen Normandie (UNICAEN), Normandie Université (NU)-École Nationale Supérieure d'Ingénieurs de Caen (ENSICAEN), Normandie Université (NU)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Centre National de la Recherche Scientifique (CNRS), and ANR-11-EQPX-0020,GENESIS,Groupe d'Etudes et de Nanoanalyses des Effets d'IrradiationS(2011)

Subjects
Materials science, Hydrogen, 010405 organic chemistry, chemistry.chemical_element, General Medicine, [CHIM.MATE]Chemical Sciences/Material chemistry, General Chemistry, 010402 general chemistry, 01 natural sciences, 7. Clean energy, Catalysis, Hydrothermal circulation, Methane, 0104 chemical sciences, chemistry.chemical_compound, chemistry, Chemical engineering, Nanocrystal, Thermal stability, Zeolite, Hydrogen production
Abstract

International audience; The current energy transition presents many technological challenges, such as the development of highly stable catalysts. Herein, we report a novel "top-down" synthesis approach for preparation of a single-site Mo-containing nanosized ZSM-5 zeolite possessing atomically dispersed framework-molybdenum homogenously distributed through the zeolite crystals. The introduction of Mo heals most of the native point defects in the zeolite structure resulting in an extremely stable material. The important features of this single-site Mo-containing ZSM-5 zeolite are provided by an in-depth spectroscopic and microscopic analysis. The material demonstrates superior thermal (up to 1000 °C), hydrothermal (steaming), and catalytic (converting methane to hydrogen and higher hydrocarbons) stability, maintaining the atomically disperse Mo, structural integrity of the zeolite, and preventing the formation of silanols.

Published
2020
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11. Exploration, explanation and exploitation of hydroxyls in zeolites

Author

Eddy Dib, Edwin B Clatworthy, Hugo Cruchade, Izabel C Medeiros-Costa, Nikolai Nesterenko, Jean-Pierre Gilson, and Svetlana Mintova

Subjects
Multidisciplinary
Abstract

The precise location and role of all types of hydroxyls in zeolites are still enigmatic, and their control permits tailoring of novel properties increasing the efficiency of catalysts and adsorbents in industrial processes for cleaner energy.

Published
2022

12. The role of mixed alkali metal cations on the formation of nanosized CHA zeolite from colloidal precursor suspension

Author

Valérie Ruaux, Svetlana Mintova, Eddy Dib, Sajjad Ghojavand, Maxime Debost, Jaafar El Fallah, Edwin B. Clatworthy, Aurélie Vicente, Laboratoire catalyse et spectrochimie (LCS), Centre National de la Recherche Scientifique (CNRS)-École Nationale Supérieure d'Ingénieurs de Caen (ENSICAEN), Normandie Université (NU)-Normandie Université (NU)-Institut de Chimie du CNRS (INC)-Université de Caen Normandie (UNICAEN), Normandie Université (NU), Laboratoire de cristallographie et sciences des matériaux (CRISMAT), École Nationale Supérieure d'Ingénieurs de Caen (ENSICAEN), Normandie Université (NU)-Normandie Université (NU)-Centre National de la Recherche Scientifique (CNRS)-Université de Caen Normandie (UNICAEN), Normandie Université (NU)-Institut de Chimie du CNRS (INC), Université de Caen Normandie (UNICAEN), Normandie Université (NU)-Normandie Université (NU)-École Nationale Supérieure d'Ingénieurs de Caen (ENSICAEN), Normandie Université (NU)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS), Normandie Université (NU)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche sur les Matériaux Avancés (IRMA), Normandie Université (NU)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Rouen Normandie (UNIROUEN), Normandie Université (NU)-Institut national des sciences appliquées Rouen Normandie (INSA Rouen Normandie), Institut National des Sciences Appliquées (INSA)-Normandie Université (NU)-Institut National des Sciences Appliquées (INSA)-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Rouen Normandie (UNIROUEN), and Institut National des Sciences Appliquées (INSA)-Normandie Université (NU)-Institut National des Sciences Appliquées (INSA)-Centre National de la Recherche Scientifique (CNRS)

Subjects
Chabazite, organic template-free, crystallization, colloidal suspension, education, 02 engineering and technology, 010402 general chemistry, inorganic cation templating, 01 natural sciences, law.invention, Suspension (chemistry), Biomaterials, Colloid, Colloid and Surface Chemistry, law, Aluminosilicate, parasitic diseases, Crystallization, Zeolite, Chemistry, [CHIM.MATE]Chemical Sciences/Material chemistry, 021001 nanoscience & nanotechnology, Alkali metal, 0104 chemical sciences, Surfaces, Coatings and Films, Electronic, Optical and Magnetic Materials, Chemical engineering, Nanocrystal, Nanozeolite, chabazite, 0210 nano-technology
Abstract

International audience; A clear understanding of the crystal formation pathways of zeolites remains one of the most challenging issues to date. Here we investigate the synthesis of nanosized chabazite (CHA) zeolites using organic template-free colloidal suspensions by varying the time of aging at room temperature and the time of hydrothermal treatment at 90 °C. The role of mixed alkali metal cations (Na+, K+, Cs+) on the formation of CHA in the colloidal suspensions was studied. Increasing the aging time of the precursor colloidal suspension from 4 to 17 days resulted in faster crystallization of CHA nanocrystals (3 h instead of 7 h at 90 °C) to afford significantly smaller particles (60 nm vs 600 nm). During the crystallization a considerable change in the content of inorganic cations in the recovered solid material was observed to coincide with the formation of the CHA nanocrystals. The Na+ cations were found to direct the formation of condensed and pre-shaped aluminosilicate particles in the colloidal precursor suspensions, while K+ cations facilitated the formation of secondary building units (SBUs) of the CHA type framework structure such as d6r and cha cages, and the Cs+ cations promoted the long-range crystalline order facilitating the crystallization of stable zeolite nanocrystals

Published
2021
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13. Room-Temperature Synthesis of BPH Zeolite Nanosheets Free of Organic Template with Enhanced Stability for Gas Separations

Author

Jean-Pierre Gilson, Philippe Boullay, Nikolai Nesterenko, Stéphanie Gascoin, Edwin B. Clatworthy, Svetlana Mintova, Maxime Debost, Nicolas Barrier, Aurélie Vicente, Jean-Pierre Dath, Laboratoire catalyse et spectrochimie (LCS), Université de Caen Normandie (UNICAEN), Normandie Université (NU)-Normandie Université (NU)-École Nationale Supérieure d'Ingénieurs de Caen (ENSICAEN), Normandie Université (NU)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS), Laboratoire de cristallographie et sciences des matériaux (CRISMAT), Normandie Université (NU)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche sur les Matériaux Avancés (IRMA), Normandie Université (NU)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Rouen Normandie (UNIROUEN), Normandie Université (NU)-Institut national des sciences appliquées Rouen Normandie (INSA Rouen Normandie), Institut National des Sciences Appliquées (INSA)-Normandie Université (NU)-Institut National des Sciences Appliquées (INSA)-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Rouen Normandie (UNIROUEN), Institut National des Sciences Appliquées (INSA)-Normandie Université (NU)-Institut National des Sciences Appliquées (INSA)-Centre National de la Recherche Scientifique (CNRS), Total Research and Technology Feluy ( [TRTF]), Centre National de la Recherche Scientifique (CNRS)-École Nationale Supérieure d'Ingénieurs de Caen (ENSICAEN), Normandie Université (NU)-Normandie Université (NU)-Institut de Chimie du CNRS (INC)-Université de Caen Normandie (UNICAEN), Normandie Université (NU), École Nationale Supérieure d'Ingénieurs de Caen (ENSICAEN), Normandie Université (NU)-Normandie Université (NU)-Centre National de la Recherche Scientifique (CNRS)-Université de Caen Normandie (UNICAEN), and Normandie Université (NU)-Institut de Chimie du CNRS (INC)

Subjects
In situ, Materials science, 010405 organic chemistry, Gas separation, 02 engineering and technology, [CHIM.MATE]Chemical Sciences/Material chemistry, 021001 nanoscience & nanotechnology, Co2 adsorption, 01 natural sciences, Template-free, 0104 chemical sciences, Colloid, Membrane, Chemical engineering, Aluminosilicate, Nanosheets, Zeolites, General Materials Science, Thin film, 0210 nano-technology, Zeolite, CO2 adsorption, Cation stabilization
Abstract

International audience; BPH-type synthetic aluminosilicate zeolite (Linde Q) nanosheets are synthesized at room temperature without organic structure-directing agents (OSDAs). The BPH nanosheets (7 nm thick, 90 nm across; Si/Al = 1.3) are formed in a colloidal suspension using a mixture of structure-directing cations (Cs+, K+, and Na+). In situ XRD reveals the high stability of the BPH nanosheets up to 500 °C under vacuum (0.021 mbar) due to the presence of Cs+. The high CO2 adsorption capacity (3.78 mmol/g) and stability of the BPH nanosheets open the door for the preparation of oriented thin films and membranes for gas separation applications.

Published
2021
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14. Enhanced Photocatalytic Hydrogen Evolution with TiO2–TiN Nanoparticle Composites

Author

Samuel Yick, MC Allison, Adrian T. Murdock, Anthony F. Masters, Edwin B. Clatworthy, Thomas Maschmeyer, and Avi Bendavid

Subjects
Materials science, Nanoparticle, chemistry.chemical_element, 02 engineering and technology, Nitride, 010402 general chemistry, 7. Clean energy, 01 natural sciences, Metal, chemistry.chemical_compound, Hydrogen evolution, Physical and Theoretical Chemistry, Composite material, 021001 nanoscience & nanotechnology, Titanium nitride, 0104 chemical sciences, Surfaces, Coatings and Films, Electronic, Optical and Magnetic Materials, General Energy, chemistry, visual_art, Titanium dioxide, visual_art.visual_art_medium, Photocatalysis, 0210 nano-technology, Tin
Abstract

Metal nitrides have potential in energy applications because of their physical and optical properties. Nanoparticle composites of titanium nitride (TiN) and titanium dioxide (TiO2) were investigate...

Published
2019
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15. Salt-enhanced photocatalytic hydrogen production from water with carbon nitride nanorod photocatalysts: cation and pH dependence

Author

Stuart A. Bartlett, Ivan V. Sergeyev, Thomas Maschmeyer, James M. Hook, Edwin B. Clatworthy, Anthony F. Masters, and Xiaobo Li

Subjects
chemistry.chemical_classification, Materials science, Extended X-ray absorption fine structure, Renewable Energy, Sustainability and the Environment, Stacking, Salt (chemistry), 02 engineering and technology, General Chemistry, 021001 nanoscience & nanotechnology, 7. Clean energy, Absorbance, chemistry.chemical_compound, chemistry, Chemical engineering, 13. Climate action, Photocatalysis, General Materials Science, Nanorod, 0210 nano-technology, Carbon nitride, Hydrogen production
Abstract

Carbon nitride polymeric semiconductors with nanorod morphology are explored as photocatalysts for efficient hydrogen evolution from water. Their composition, structure, optical properties and photocatalytic performance are found to be highly sensitive to the presence of added salts in the photocatalytic reaction solution. In potassium-incorporated carbon nitride (CNK), the photocatalytic hydrogen evolution activity is significantly enhanced with the addition of salts into the reaction solution by up to ∼9 times, depending on the salt added. Similarly, cation-dependent red-shifts in the UV-vis absorbance of CNK are observed. We find that the effect of the salts on the photocatalytic activity and optical properties of CNK is further modulated by the solution pH. The CNK nanorods form a compact layer stacking structure for certain cations, such as for K+ but not Li+. The enhancement of the photoactivity of CNK in the presence of salts is attributed to improved light harvesting ability, a dielectric screening effect, and the nanorod structure. An obvious and consistent potassium–potassium interaction is observed via EXAFS, indicating a high degree of order, likely in the form of a potassium channel or ordered layer. The strong sensitivity of CNK materials to the photocatalytic environment yields dramatic changes in structure, optical properties and photoactivity, thus providing a new experimental variable for photocatalyst material development and optimization.

Published
2019
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16. Investigating homogeneous Co/Br−/H2O2 catalysed oxidation of lignin model compounds in acetic acid

Author

Edwin B. Clatworthy, Anthony F. Masters, Thomas Maschmeyer, Julia L. Picone-Murray, Richard Maschmeyer, and Alexander K. L. Yuen

Subjects
010405 organic chemistry, Syringol, Substrate (chemistry), 010402 general chemistry, 01 natural sciences, Catalysis, 0104 chemical sciences, chemistry.chemical_compound, Acetic acid, chemistry, Lignin, Organic chemistry, Moiety, Phenols, Guaiacol, Bond cleavage
Abstract

Oxidation of α-O-4, β-O-4 and monomeric lignin model compounds by Co/Br−/H2O2 in acetic acid at 70 °C was investigated. Co and Br− were introduced as cobalt acetate tetrahydrate and KBr respectively. The degree of methoxylation of the substrate was found to affect its reactivity. For the α-O-4 model compounds, increased methoxylation of the benzyl moiety influenced product selectivity, while increased methoxylation of the phenolic moiety increased substrate conversion. The β-O-4 model compounds exhibited similar conversions to the α-O-4 models, but afforded a lesser amount of monomeric products. The formation of phenol and guaiacol from α-O-4 bond cleavage inhibited substrate conversion and sequestered oxidation products due to the formation of phenoxy radicals and polyguaiacols. Similar to the α-O-4 model compounds, increased methoxylation of the monomers changed the types of products formed, from polyphenols (phenol and guaiacol) to quinones (syringol). The behaviour of syringol was explored extensively, revealing that the corresponding 1,4-hydroquinone strongly inhibited syringol oxidation, and the syringol oxidation product, 4,4′-diphenoquinone, was susceptible to over-oxidation. The deleterious effects of phenols on oxidation of an α-O-4 model could be reduced by substitution of the Br− co-catalyst with N-hydroxyphthalimide (NHPI), improving substrate conversion and product selectivity.

Published
2019
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17. Structural Investigation of Cobalt Oxide Clusters Derived from Molecular Cobalt Cubane, Trimer, and Dimer Oligomers in a Phosphate Electrolyte

Author

Edwin B. Clatworthy, Thomas Maschmeyer, Stuart A. Bartlett, Anthony F. Masters, and Xiaobo Li

Subjects
X-ray absorption spectroscopy, 010405 organic chemistry, Chemistry, Dimer, Inorganic chemistry, chemistry.chemical_element, Trimer, Electrolyte, 010402 general chemistry, 01 natural sciences, 3. Good health, 0104 chemical sciences, Surfaces, Coatings and Films, Electronic, Optical and Magnetic Materials, Catalysis, Crystallography, chemistry.chemical_compound, General Energy, Cubane, Physical and Theoretical Chemistry, Cobalt oxide, Cobalt
Abstract

Cobalt oxide clusters were formed from three molecular cobalt oligomers, the Co-cubane, [Co4(μ3-O)4(μ-OAc)4(py)4], Co-trimer, [Co3(μ3-O)(μ-OAc)6(py)3][PF6], and Co-dimer, [Co2(μ-OH)2(μ-OAc)(OAc)2(py)4][PF6], in phosphate buffer electrolyte after aging. Phosphate is essential for the formation of these cobalt oxide clusters. XAS characterization shows the cobalt oxide clusters are CoII/IIIOx clusters with CoII(O)4 and CoIII(O)6 subunits. The cobalt oxide clusters formed have a structure similar to that of aged “CoPi” oxygen evolution catalysts prepared by electrodeposition.

Published
2017
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18. Flexible Template-Free RHO Nanosized Zeolite for Selective CO 2 Adsorption

Author

Svetlana Mintova, Jean-Pierre Dath, Nikolai Nesterenko, Fabien Laine, Jean-Pierre Gilson, Julien Grand, Maxime Debost, Nicolas Barrier, Philippe Boullay, Edwin B. Clatworthy, Laboratoire catalyse et spectrochimie (LCS), Centre National de la Recherche Scientifique (CNRS)-École Nationale Supérieure d'Ingénieurs de Caen (ENSICAEN), Normandie Université (NU)-Normandie Université (NU)-Institut de Chimie du CNRS (INC)-Université de Caen Normandie (UNICAEN), Normandie Université (NU), Laboratoire de cristallographie et sciences des matériaux (CRISMAT), École Nationale Supérieure d'Ingénieurs de Caen (ENSICAEN), Normandie Université (NU)-Normandie Université (NU)-Centre National de la Recherche Scientifique (CNRS)-Université de Caen Normandie (UNICAEN), Normandie Université (NU)-Institut de Chimie du CNRS (INC), Université de Caen Normandie (UNICAEN), Normandie Université (NU)-Normandie Université (NU)-École Nationale Supérieure d'Ingénieurs de Caen (ENSICAEN), Normandie Université (NU)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS), Normandie Université (NU)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche sur les Matériaux Avancés (IRMA), Normandie Université (NU)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Rouen Normandie (UNIROUEN), Normandie Université (NU)-Institut national des sciences appliquées Rouen Normandie (INSA Rouen Normandie), Institut National des Sciences Appliquées (INSA)-Normandie Université (NU)-Institut National des Sciences Appliquées (INSA)-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Rouen Normandie (UNIROUEN), Institut National des Sciences Appliquées (INSA)-Normandie Université (NU)-Institut National des Sciences Appliquées (INSA)-Centre National de la Recherche Scientifique (CNRS), and Total Research and Technology Feluy ( [TRTF])

Subjects
Template free, Materials science, Physical and chemical processes, General Chemical Engineering, Natural-gas processing, Sorption, 02 engineering and technology, General Chemistry, [CHIM.MATE]Chemical Sciences/Material chemistry, 010402 general chemistry, 021001 nanoscience & nanotechnology, 01 natural sciences, 0104 chemical sciences, Adsorption, Chemical structure, Chemical engineering, Cations, Zeolites, Materials Chemistry, 0210 nano-technology, Selectivity, Zeolite, Flue
Abstract

International audience; Flexible small-pore zeolites are interesting candidates for flue and natural gas processing due to their high sorption capacity and selectivity. It is generally accepted that their high CO2/CH4 selectivity is due to cation gating behavior such as the "trapdoor" effect or cation-controlled molecular sieving. Herein, nanosized RHO-type zeolite containing only inorganic cations (Na + and Cs +) has been prepared from a colloidal precursor suspension at 90 °C for 1 h without the use of expensive organic structure directing agents. The high Cs content significantly improved the thermal stability of the RHO nanocrystals up to 550 °C. The flexibility of the RHO cages upon water adsorption/desorption is demonstrated. The dehydration of the nanosized RHO zeolite resulted in two dehydrated RHO phases, the first one presents an enlargement of the cubic unit cell and a transformation from distorted to the more regular d8r units, and the second one presents a reduction of the cubic unit cell and an increase of the distortion of the d8r units. The 8-rings elliptical distortions of the as synthesized RHO (hydrated form) of 1.87 Å changed to 0.94 Å and 2.16 Å for the two dehydrated RHO forms. The flexibility of the nanosized RHO zeolite is due to the ability of the Cs + cation to displace out from and in to the D8R window sites which is of great importance for controlling the selective adsorption capacity of the RHO zeolite. The flexible RHO-type nanosized zeolite exhibited great selectivity towards CO2 over CH4. The adsorption capacity is retained after 10 cycles of CO2 adsorption/desorption and the crystalline structure is fully preserved.

Published
2020
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19. Electrochemical investigation of [Co4(μ3-O)4(μ-OAc)4(py)4] and peroxides by cyclic voltammetry

Author

Thomas Maschmeyer, Edwin B. Clatworthy, Anthony F. Masters, and Xiaobo Li

Subjects
010405 organic chemistry, Inorganic chemistry, Metals and Alloys, chemistry.chemical_element, General Chemistry, Oxidative phosphorylation, 010402 general chemistry, Electrochemistry, 01 natural sciences, Peroxide, Redox, Catalysis, 0104 chemical sciences, Surfaces, Coatings and Films, Electronic, Optical and Magnetic Materials, chemistry.chemical_compound, chemistry, Cubane, Materials Chemistry, Ceramics and Composites, Cyclic voltammetry, Acetonitrile, Cobalt
Abstract

Two oxidative redox processes of the neutral cobalt(III) cubane, [Co4(μ3-O)4(μ-OAc)4(py)4], were investigated by cyclic voltammetry at a glassy carbon electrode in acetonitrile. In addition to the first quasi-reversible one-electron oxidation at E1/2 = 0.283 V vs. Fc0/+, a second quasi-reversible one-electron oxidation was observed at E1/2 = 1.44 V vs. Fc0/+. Oxidation at this potential does not facilitate water oxidation. In the presence of tert-butylhydroperoxide the peak current of this second oxidation increases, suggesting oxidation of the peroxide by the doubly oxidised cubane.

Published
2016
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20. Electrochemical investigation of [Co

Author

Edwin B, Clatworthy, Xiaobo, Li, Anthony F, Masters, and Thomas, Maschmeyer

Abstract

Two oxidative redox processes of the neutral cobalt(iii) cubane, [Co

Published
2016

21. Molecular Cobalt Clusters as Precursors of Distinct Active Species in Electrochemical, Photochemical, and Photoelectrochemical Water Oxidation Reactions in Phosphate Electrolytes

Author

Thomas Maschmeyer, Anthony F. Masters, Edwin B. Clatworthy, and Xiaobo Li

Subjects
Organic Chemistry, Oxygen evolution, chemistry.chemical_element, General Chemistry, Electrolyte, Photochemistry, Electrochemistry, Redox, Catalysis, chemistry.chemical_compound, chemistry, Cubane, Cobalt oxide, Cobalt
Abstract

Three cobalt model molecular compounds, Co-cubane ([Co4 (µ3 -O)4 (µ-OAc)4 py4 ]), Co-trimer ([Co3 (μ3 -O)(µ-OAc)6 py3 ]PF6 ), and Co-dimer ([Co2 (μ-OH)2 (µ-OAc)(OAc)2 py4 ]PF6 ), are investigated as water oxidation reaction (WOR) catalysts, using electrochemical, photochemical, and photoelectrochemical methodologies in phosphate electrolyte. The actual species contributing to the catalytic activity observed in the WOR are derived from the transformation of these cobalt compounds. The catalytic activity observed is highly dependent on the initial compound structure and on the particular WOR methodology used. Co-cubane shows no activity in the electrochemical WOR and negligible activity in the photochemical WOR, but is active in the photoelectrochemical WOR, in which it behaves as a precursor to catalytically active species. Co-dimer also shows no activity in the electrochemical WOR, but behaves as a precursor to catalytically active species in both the photochemical and photoelectrochemical WOR experiments. Co-trimer behaves as a precursor to catalytically active species in all three of the WOR methodologies.

Published
2015

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