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Ulucan T, Wang J, Onur E, Chen S, Behrens M, Weidenthaler C. Unveiling the Structure-Property Relationship of MgO-Supported Ni Ammonia Decomposition Catalysts from Bulk to Atomic Structure by In Situ/Operando Studies. ACS Catal 2024; 14:2828-2841. [PMID: 38449535 PMCID: PMC10913046 DOI: 10.1021/acscatal.3c05629] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2023] [Revised: 01/21/2024] [Accepted: 01/23/2024] [Indexed: 03/08/2024]
Abstract
Ammonia is currently being studied intensively as a hydrogen carrier in the context of the energy transition. The endothermic decomposition reaction requires the use of suitable catalysts. In this study, transition metal Ni on MgO as a support is investigated with respect to its catalytic properties. The synthesis method and the type of activation process contribute significantly to the catalytic properties. Both methods, coprecipitation (CP) and wet impregnation (WI), lead to the formation of Mg1-xNixO solid solutions as catalyst precursors. X-ray absorption studies reveal that CP leads to a more homogeneous distribution of Ni2+ cations in the solid solution, which is advantageous for a homogeneous distribution of active Ni catalysts on the MgO support. Activation in hydrogen at 900 °C reduces nickel, which migrates to the support surface and forms metal nanoparticles between 6 nm (CP) and 9 nm (WI), as shown by ex situ STEM. Due to the homogeneously distributed Ni2+ cations in the solid solution structure, CP samples are more difficult to activate and require harsher conditions to reduce the Ni. The combination of in situ X-ray diffraction (XRD) and operando total scattering experiments allows a structure-property investigation of the bulk down to the atomic level during the catalytic reaction. Activation in H2 at 900 °C for 2 h leads to the formation of large Ni particles (20-30 nm) for the samples synthesized by the WI method, whereas Ni stays significantly smaller for the CP samples (10-20 nm). Sintering has a negative influence on the catalytic conversion of the WI samples, which is significantly lower compared to the conversion observed for the CP samples. Interestingly, metallic Ni redisperses during cooling and becomes invisible for conventional XRD but can still be detected by total scattering methods. The conditions of activation in NH3 at 650 °C are not suitable to form enough reduced Ni nanoparticles from the solid solution and are, therefore, not a suitable activation procedure. The activity steadily increases in the samples activated at 650 °C in NH3 (Group 1) compared to the samples activated at 650 °C in H2 and then reaches the best activity in the samples activated at 900 °C in H2. Only the combination of complementary in situ and ex situ characterization methods provides enough information to identify important structure-property relationships among these promising ammonia decomposition catalysts.
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Affiliation(s)
- Tolga
H. Ulucan
- Max-Planck-Institut
für Kohlenforschung, Kaiser-Wilhelm-Platz 1, DE-45470 Mülheim an der Ruhr, Germany
| | - Jihao Wang
- Institute
for Inorganic Chemistry Christian-Albrechts-Universität zu
Kiel Max-Eyth-Str. 2, 24118 Kiel, Germany
| | - Ezgi Onur
- Max-Planck-Institut
für Kohlenforschung, Kaiser-Wilhelm-Platz 1, DE-45470 Mülheim an der Ruhr, Germany
| | - Shilong Chen
- Institute
for Inorganic Chemistry Christian-Albrechts-Universität zu
Kiel Max-Eyth-Str. 2, 24118 Kiel, Germany
| | - Malte Behrens
- Institute
for Inorganic Chemistry Christian-Albrechts-Universität zu
Kiel Max-Eyth-Str. 2, 24118 Kiel, Germany
| | - Claudia Weidenthaler
- Max-Planck-Institut
für Kohlenforschung, Kaiser-Wilhelm-Platz 1, DE-45470 Mülheim an der Ruhr, Germany
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Gianolio D, Higham MD, Quesne MG, Aramini M, Xu R, Large AI, Held G, Velasco-Vélez JJ, Haevecker M, Knop-Gericke A, Genovese C, Ampelli C, Schuster ME, Perathoner S, Centi G, Catlow CRA, Arrigo R. Interfacial Chemistry in the Electrocatalytic Hydrogenation of CO 2 over C-Supported Cu-Based Systems. ACS Catal 2023; 13:5876-5895. [PMID: 37180964 PMCID: PMC10167656 DOI: 10.1021/acscatal.3c01288] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2023] [Revised: 03/31/2023] [Indexed: 05/16/2023]
Abstract
Operando soft and hard X-ray spectroscopic techniques were used in combination with plane-wave density functional theory (DFT) simulations to rationalize the enhanced activities of Zn-containing Cu nanostructured electrocatalysts in the electrocatalytic CO2 hydrogenation reaction. We show that at a potential for CO2 hydrogenation, Zn is alloyed with Cu in the bulk of the nanoparticles with no metallic Zn segregated; at the interface, low reducible Cu(I)-O species are consumed. Additional spectroscopic features are observed, which are identified as various surface Cu(I) ligated species; these respond to the potential, revealing characteristic interfacial dynamics. Similar behavior was observed for the Fe-Cu system in its active state, confirming the general validity of this mechanism; however, the performance of this system deteriorates after successive applied cathodic potentials, as the hydrogen evolution reaction then becomes the main reaction pathway. In contrast to an active system, Cu(I)-O is now consumed at cathodic potentials and not reversibly reformed when the voltage is allowed to equilibrate at the open-circuit voltage; rather, only the oxidation to Cu(II) is observed. We show that the Cu-Zn system represents the optimal active ensembles with stabilized Cu(I)-O; DFT simulations rationalize this observation by indicating that Cu-Zn-O neighboring atoms are able to activate CO2, whereas Cu-Cu sites provide the supply of H atoms for the hydrogenation reaction. Our results demonstrate an electronic effect exerted by the heterometal, which depends on its intimate distribution within the Cu phase and confirms the general validity of these mechanistic insights for future electrocatalyst design strategies.
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Affiliation(s)
- Diego Gianolio
- Diamond
Light Source Ltd., Harwell
Science & Innovation Campus, Didcot, Oxfordshire OX11 0DE, U.K.
| | - Michael D. Higham
- Cardiff
Catalysis Institute, School of Chemistry, Cardiff University, Main Building, Park Place, Cardiff, Wales CF10 3AT, U.K.
- UK Catalysis
Hub, Research Complex at Harwell, Rutherford
Appleton Laboratory, R92, Harwell, Oxfordshire OX11 0FA, U.K.
- Department
of Chemistry, University College London, 20 Gordon Street, London WC1H 0AJ, U.K.
| | - Matthew G. Quesne
- Cardiff
Catalysis Institute, School of Chemistry, Cardiff University, Main Building, Park Place, Cardiff, Wales CF10 3AT, U.K.
- UK Catalysis
Hub, Research Complex at Harwell, Rutherford
Appleton Laboratory, R92, Harwell, Oxfordshire OX11 0FA, U.K.
| | - Matteo Aramini
- Diamond
Light Source Ltd., Harwell
Science & Innovation Campus, Didcot, Oxfordshire OX11 0DE, U.K.
| | - Ruoyu Xu
- Department
of Chemical Engineering, University College
London, 20 Gordon Street, London WC1H 0AJ, U.K.
| | - Alex I. Large
- Diamond
Light Source Ltd., Harwell
Science & Innovation Campus, Didcot, Oxfordshire OX11 0DE, U.K.
| | - Georg Held
- Diamond
Light Source Ltd., Harwell
Science & Innovation Campus, Didcot, Oxfordshire OX11 0DE, U.K.
| | - Juan-Jesús Velasco-Vélez
- Max-Planck-Institut
für Chemische Energiekonversion, Stiftstrasse 34-36, 45470 Mülheim an der Ruhr, Germany
- Department
of Inorganic Chemistry, Fritz-Haber-Institut
der Max-Planck Gesellschaft, Faradayweg 4-6, 14195 Berlin, Germany
| | - Michael Haevecker
- Max-Planck-Institut
für Chemische Energiekonversion, Stiftstrasse 34-36, 45470 Mülheim an der Ruhr, Germany
- Department
of Inorganic Chemistry, Fritz-Haber-Institut
der Max-Planck Gesellschaft, Faradayweg 4-6, 14195 Berlin, Germany
| | - Axel Knop-Gericke
- Max-Planck-Institut
für Chemische Energiekonversion, Stiftstrasse 34-36, 45470 Mülheim an der Ruhr, Germany
- Department
of Inorganic Chemistry, Fritz-Haber-Institut
der Max-Planck Gesellschaft, Faradayweg 4-6, 14195 Berlin, Germany
| | - Chiara Genovese
- Department
of ChiBioFarAm, ERIC aisbl and CASPE/INSTM, University of Messina, V. le F.Stagno D’ Alcontres 31, 98166 Messina, Italy
| | - Claudio Ampelli
- Department
of ChiBioFarAm, ERIC aisbl and CASPE/INSTM, University of Messina, V. le F.Stagno D’ Alcontres 31, 98166 Messina, Italy
| | | | - Siglinda Perathoner
- Department
of ChiBioFarAm, ERIC aisbl and CASPE/INSTM, University of Messina, V. le F.Stagno D’ Alcontres 31, 98166 Messina, Italy
| | - Gabriele Centi
- Department
of ChiBioFarAm, ERIC aisbl and CASPE/INSTM, University of Messina, V. le F.Stagno D’ Alcontres 31, 98166 Messina, Italy
| | - C. Richard A. Catlow
- Diamond
Light Source Ltd., Harwell
Science & Innovation Campus, Didcot, Oxfordshire OX11 0DE, U.K.
- Cardiff
Catalysis Institute, School of Chemistry, Cardiff University, Main Building, Park Place, Cardiff, Wales CF10 3AT, U.K.
- UK Catalysis
Hub, Research Complex at Harwell, Rutherford
Appleton Laboratory, R92, Harwell, Oxfordshire OX11 0FA, U.K.
- Department
of Chemistry, University College London, 20 Gordon Street, London WC1H 0AJ, U.K.
| | - Rosa Arrigo
- Diamond
Light Source Ltd., Harwell
Science & Innovation Campus, Didcot, Oxfordshire OX11 0DE, U.K.
- School
of Science, Engineering and Environment, University of Salford, Cockcroft Building, Salford, Greater Manchester M5 4WT, U.K.
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Parsons J, Luna C, Botez C, Elizalde J, Gardea-Torresdey J. Microwave Assisted Synthesis of Iron(III) Oxyhydroxides/Oxides Characterized Using Transmission Electron Microscopy, X-ray Diffraction, and X-ray Absorption Spectroscopy. J Phys Chem Solids 2009; 70:555-560. [PMID: 20161181 PMCID: PMC2726966 DOI: 10.1016/j.jpcs.2008.12.017] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/03/2023]
Abstract
Microwave assisted synthesis of iron oxide/oxyhydroxide nanophases was conducted using iron(III) chloride titrated with sodium hydroxide at seven different temperatures from 100 degrees C to 250 degrees C with pulsed microwaves. From the XRD results, it was determined that there were two different phases synthesized during the reactions which were temperature dependent. At the lower temperatures, 100 degrees C and 125 degrees C, it was determined that an iron oxyhydroxide chloride was synthesized. Whereas, at higher temperatures, at 150 degrees C and above, iron(III) oxide was synthesized. From the XRD, we also determined the FWHM and the average size of the nanoparticles using the Scherrer equation. The average size of the nanoparticles synthesized using the experimental conditions were 17, 21, 12, 22, 26, 33, 28 nm, respectively for the reactions from 100 degrees C to 250 degrees C. The particles also had low anisotropy indicating spherical nanoparticles, which was later confirmed using TEM. Finally, XAS studies show that the iron present in the nanophase was present as iron(III) coordinated to six oxygen atoms in the first coordination shell. The higher coordination shells also conform very closely to the ideal or bulk crystal structures.
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Affiliation(s)
- J.G. Parsons
- University of Texas at El Paso Department of Chemistry, 500 W University Ave El Paso TX 79986
| | - C. Luna
- University of Texas at El Paso Environmental Science and Engineering PhD program, 500 W University Ave. El Paso TX 79968
| | - C.E. Botez
- University of Texas at El Paso Department of Physics, 500 W University Ave El Paso TX 79986
| | - J. Elizalde
- University of Texas at El Paso Department of Physics, 500 W University Ave El Paso TX 79986
| | - J.L. Gardea-Torresdey
- University of Texas at El Paso Department of Chemistry, 500 W University Ave El Paso TX 79986
- University of Texas at El Paso Environmental Science and Engineering PhD program, 500 W University Ave. El Paso TX 79968
- Corresponding Author: , phone: (915)747-5359, fax: (915)-747-5847
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