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Irvine GJ, Smith RI, Jones MO, Irvine JTS. Order-disorder and ionic conductivity in calcium nitride-hydride. Nat Commun 2023; 14:4389. [PMID: 37474517 PMCID: PMC10359262 DOI: 10.1038/s41467-023-40025-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2023] [Accepted: 07/05/2023] [Indexed: 07/22/2023] Open
Abstract
Recently nitrogen-hydrogen compounds have successfully been applied as co-catalysts for mild conditions ammonia synthesis. Ca2NH was shown to act as a H2 sink during reaction, with H atoms from its lattice being incorporated into the NH3(g) product. Thus the ionic transport and diffusion properties of the N-H co-catalyst are fundamentally important to understanding and developing such syntheses. Here we show hydride ion conduction in these materials. Two distinct calcium nitride-hydride Ca2NH phases, prepared via different synthetic paths are found to show dramatically different properties. One phase (β) shows fast hydride ionic conduction properties (0.08 S/cm at 600 °C), on a par with the best binary ionic hydrides and 10 times higher than CaH2, whilst the other (α) is 100 times less conductive. An in situ combined analysis techniques reveals that the effective β-phase conducts ions via a vacancy-mediated phenomenon in which the charge carrier concentration is dependent on the ion concentration in the secondary site and by extension the vacancy concentration in the main site.
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Affiliation(s)
- G J Irvine
- Chemistry, University of St Andrews, St Andrews, Scotland, KY16 9ST, UK.
| | - Ronald I Smith
- ISIS Neutron and Muon Source, Rutherford Appleton Laboratory, Oxford, England, OX11 0QX, UK
| | - M O Jones
- Chemistry, University of St Andrews, St Andrews, Scotland, KY16 9ST, UK
- ISIS Neutron and Muon Source, Rutherford Appleton Laboratory, Oxford, England, OX11 0QX, UK
| | - J T S Irvine
- Chemistry, University of St Andrews, St Andrews, Scotland, KY16 9ST, UK.
- ISIS Neutron and Muon Source, Rutherford Appleton Laboratory, Oxford, England, OX11 0QX, UK.
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Caux M, Menard H, AlSalik YM, Irvine JTS, Idriss H. Photo-catalytic hydrogen production over Au/g-C 3N 4: effect of gold particle dispersion and morphology. Phys Chem Chem Phys 2019; 21:15974-15987. [PMID: 31294442 DOI: 10.1039/c9cp02241d] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
Metal/semiconductor interactions affect electron transfer rates and this is central to photocatalytic hydrogen ion reduction. While this interaction has been studied in great detail on metal oxide semiconductors, not much is known of Au particles on top of polymeric semiconductors. The effects of gold nanoparticle size and dispersion on top of g-C3N4 were studied by core and valence level spectroscopy and transmission electron microscopy in addition to catalytic tests. The as-prepared, non-calcined catalysts displayed Au particles with uniform dimension (mean particle size = 1.8 nm) and multiple electronic states: XPS Au 4f7/2 lines at 84.9 and 87.1 eV (each with a spin-orbit splitting of 3.6-3.7 eV). These particles, which did not show localized surface plasmon resonance (LSPR), before the reaction, doubled in size after the reaction giving a pronounced LSPR at about 550 nm. The effect of the heating environment on these particles (in air or in H2) was further investigated. While heating in H2 gave Au nanoparticles of different shapes, heating under O2 gave exclusively spherical particles. Similar activity towards photocatalytic hydrogen ion reduction under UV excitation was seen in both cases, however. XPS Au 4f analyses indicated that an increase in deposition time, during catalyst preparation, resulted in an increase in the initial fraction of oxidized gold particles, which were easily reduced under hydrogen. The valence band region for Au/gC3N4 was further studied in an effort to compare it to what is already known for Au/metal oxide semiconductors. A shift of over 2 eV for the Au 5d doublets was noticed between reduced and oxidized gold particles with mean particle sizes between 2 and 6 nm, which is consistent with the final state effect. A narrow range of gold loading for optimal catalytic performance was seen, where it seems that a density of one Au particle per 10 × 10 nm2 is the most suitable. Particle size and shape had a minor effect on performance, which may indicate the absence of a plasmonic effect on the reaction rate.
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Affiliation(s)
- M Caux
- School of Chemistry, University of St Andrews, St Andrews, UK.
| | - H Menard
- Leverhulme Research Centre for Forensic Science, University of Dundee, Dundee, UK
| | - Y M AlSalik
- SABIC-Corporate Research and Development (CRD), KAUST, Thuwal, Saudi Arabia.
| | - J T S Irvine
- School of Chemistry, University of St Andrews, St Andrews, UK.
| | - H Idriss
- SABIC-Corporate Research and Development (CRD), KAUST, Thuwal, Saudi Arabia.
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Macias-Montero M, Askari S, Mitra S, Rocks C, Ni C, Svrcek V, Connor PA, Maguire P, Irvine JTS, Mariotti D. Energy band diagram of device-grade silicon nanocrystals. Nanoscale 2016; 8:6623-6628. [PMID: 26939617 DOI: 10.1039/c5nr07705b] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
Device grade silicon nanocrystals (NCs) are synthesized using an atmospheric-pressure plasma technique. The Si NCs have a small and well defined size of about 2.3 nm. The synthesis system allows for the direct creation of thin films, enabling a range of measurements to be performed and easy implementation of this material in different devices. The chemical stability of the Si NCs is evaluated, showing relatively long-term durability thanks to hydrogen surface terminations. Optical and electrical characterization techniques, including Kelvin probe, ultraviolet photoemission spectroscopy and Mott-Schottky analysis, are employed to determine the energy band diagram of the Si NCs.
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Affiliation(s)
- M Macias-Montero
- Nanotechnology & Integrated Bio-Engineering Centre (NIBEC), University of Ulster, BT37 0QB, UK.
| | - S Askari
- Nanotechnology & Integrated Bio-Engineering Centre (NIBEC), University of Ulster, BT37 0QB, UK.
| | - S Mitra
- Nanotechnology & Integrated Bio-Engineering Centre (NIBEC), University of Ulster, BT37 0QB, UK.
| | - C Rocks
- Nanotechnology & Integrated Bio-Engineering Centre (NIBEC), University of Ulster, BT37 0QB, UK.
| | - C Ni
- School of Chemistry, University of St Andrews, St Andrews, Fife, KY16 9ST, UK
| | - V Svrcek
- Research Center for Photovoltaic Technologies, National Institute of Advanced Industrial Science and Technology (AIST), Tsukuba, 305-8568, Japan
| | - P A Connor
- School of Chemistry, University of St Andrews, St Andrews, Fife, KY16 9ST, UK
| | - P Maguire
- Nanotechnology & Integrated Bio-Engineering Centre (NIBEC), University of Ulster, BT37 0QB, UK.
| | - J T S Irvine
- School of Chemistry, University of St Andrews, St Andrews, Fife, KY16 9ST, UK
| | - D Mariotti
- Nanotechnology & Integrated Bio-Engineering Centre (NIBEC), University of Ulster, BT37 0QB, UK.
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Abstract
Liquid salts comprising molten salts and ionic liquids offer important media to address both energy and materials challenges. Here we review topics presented in this Faraday Discussion volume related to improved electrowinning of metals, optimisation of processes, new electrochemical device concepts, chemistry in ionic liquids, conversion of biomass, carbon chemistry and nuclear applications. The underlying phenomenology is then reviewed and commentary given. Some future applications are then discussed, further exemplifying the high potential rewards achievable from these chemistries.
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Harwell JR, Baikie TK, Baikie ID, Payne JL, Ni C, Irvine JTS, Turnbull GA, Samuel IDW. Probing the energy levels of perovskite solar cells via Kelvin probe and UV ambient pressure photoemission spectroscopy. Phys Chem Chem Phys 2016; 18:19738-45. [DOI: 10.1039/c6cp02446g] [Citation(s) in RCA: 75] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
We present a study of the energy levels present in a perovskite solar cell using Kelvin probe and UV air photoemission measurements. By constructing a detailed map of the energy levels in the system we are able to predict the maximum open circuit voltage of the solar cell.
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Affiliation(s)
- J. R. Harwell
- Organic Semiconductor Centre
- SUPA
- School of Physics and Astronomy
- University of St Andrews
- St Andrews
| | - T. K. Baikie
- Organic Semiconductor Centre
- SUPA
- School of Physics and Astronomy
- University of St Andrews
- St Andrews
| | | | - J. L. Payne
- EaSTChem
- School of Chemistry
- St Andrews University
- UK
| | - C. Ni
- EaSTChem
- School of Chemistry
- St Andrews University
- UK
| | | | - G. A. Turnbull
- Organic Semiconductor Centre
- SUPA
- School of Physics and Astronomy
- University of St Andrews
- St Andrews
| | - I. D. W. Samuel
- Organic Semiconductor Centre
- SUPA
- School of Physics and Astronomy
- University of St Andrews
- St Andrews
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Fina F, Ménard H, Irvine JTS. The effect of Pt NPs crystallinity and distribution on the photocatalytic activity of Pt-g-C3N4. Phys Chem Chem Phys 2015; 17:13929-36. [PMID: 25948234 DOI: 10.1039/c5cp00560d] [Citation(s) in RCA: 70] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Loading of a co-catalyst on the surface of a semiconductor photocatalyst is often carried out without considering the effect of the loading procedure on the final product. The present study looks in detail at the effect that the loading method has on the morphology and final composition of platinum-based nanoparticles by means of XPS and TEM analysis. Additionally, reduction pre-treatments are performed to investigate how the coverage, crystallinity and composition of the NPs affect the photocatalytic H2 evolution. The activity of Pt-g-C3N4 can significantly be enhanced by controlling the properties of the co-catalyst NPs.
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Affiliation(s)
- F Fina
- School of Chemistry, University of St Andrews, St Andrews, KY16 9ST, Scotland, UK.
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Verbraeken MC, Ramos T, Agersted K, Ma Q, Savaniu CD, Sudireddy BR, Irvine JTS, Holtappels P, Tietz F. Modified strontium titanates: from defect chemistry to SOFC anodes. RSC Adv 2015. [DOI: 10.1039/c4ra09751c] [Citation(s) in RCA: 67] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
A review describing how compositional design of modified strontium titanates can lead to conductive, redox stable SOFC anodes.
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Affiliation(s)
| | - T. Ramos
- DTU Energy Conversion and Storage
- Technical University of Denmark
- DK-4000 Roskilde
- Denmark
| | - K. Agersted
- DTU Energy Conversion and Storage
- Technical University of Denmark
- DK-4000 Roskilde
- Denmark
| | - Q. Ma
- Forschungszentrum Jülich GmbH
- Institut für Energieforschung (IEK-1)
- DE-52425 Jülich
- Germany
| | - C. D. Savaniu
- School of Chemistry
- University of St Andrews
- St Andrews
- UK
| | - B. R. Sudireddy
- DTU Energy Conversion and Storage
- Technical University of Denmark
- DK-4000 Roskilde
- Denmark
| | | | - P. Holtappels
- DTU Energy Conversion and Storage
- Technical University of Denmark
- DK-4000 Roskilde
- Denmark
| | - F. Tietz
- Forschungszentrum Jülich GmbH
- Institut für Energieforschung (IEK-1)
- DE-52425 Jülich
- Germany
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Da'as EH, Irvine JTS, Traversa E, Boulfrad S. Controllable Impregnation Via Inkjet Printing for the Fabrication of Solid Oxide Cell Air Electrodes. ACTA ACUST UNITED AC 2013. [DOI: 10.1149/05701.1851ecst] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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Konysheva EY, Bonaccorso AD, Irvine JTS. Electrochemical characteristics of cathodes based on perovskites modified by ceria. RUSS J ELECTROCHEM+ 2010. [DOI: 10.1134/s1023193510070141] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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Atkinson A, Barnett S, Gorte RJ, Irvine JTS, McEvoy AJ, Mogensen M, Singhal SC, Vohs J. Advanced anodes for high-temperature fuel cells. Nat Mater 2004; 3:17-27. [PMID: 14704781 DOI: 10.1038/nmat1040] [Citation(s) in RCA: 313] [Impact Index Per Article: 15.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
Fuel cells will undoubtedly find widespread use in this new millennium in the conversion of chemical to electrical energy, as they offer very high efficiencies and have unique scalability in electricity-generation applications. The solid-oxide fuel cell (SOFC) is one of the most exciting of these energy technologies; it is an all-ceramic device that operates at temperatures in the range 500-1,000 degrees C. The SOFC offers certain advantages over lower temperature fuel cells, notably its ability to use carbon monoxide as a fuel rather than being poisoned by it, and the availability of high-grade exhaust heat for combined heat and power, or combined cycle gas-turbine applications. Although cost is clearly the most important barrier to widespread SOFC implementation, perhaps the most important technical barriers currently being addressed relate to the electrodes, particularly the fuel electrode or anode. In terms of mitigating global warming, the ability of the SOFC to use commonly available fuels at high efficiency, promises an effective and early reduction in carbon dioxide emissions, and hence is one of the lead new technologies for improving the environment. Here, we discuss recent developments of SOFC fuel electrodes that will enable the better use of readily available fuels.
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Affiliation(s)
- A Atkinson
- Department of Materials, Imperial College, London SW7 2BP, UK
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Sagoe-Crentsil KK, Glasser FP, Irvine JTS. Electrochemical characteristics of reinforced concrete corrosion as determined by impedance spectroscopy. ACTA ACUST UNITED AC 1992. [DOI: 10.1179/bcj.1992.27.2.113] [Citation(s) in RCA: 53] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/31/2022]
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