1
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Grinter D, Shaw BJA, Pang CL, Yim CM, Muryn CA, Hall CA, Maccherozzi F, Dhesi SS, Suzuki M, Yasue T, Koshikawa T, Thornton G. Fabrication of Isolated Iron Nanowires. J Phys Chem Lett 2023; 14:8507-8512. [PMID: 37722000 PMCID: PMC10544030 DOI: 10.1021/acs.jpclett.3c02362] [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: 08/23/2023] [Accepted: 09/14/2023] [Indexed: 09/20/2023]
Abstract
Nanoscale interconnects are an important component of molecular electronics. Here we use X-ray spectromicroscopy techniques as well as scanning probe methods to explore the self-assembled growth of insulated iron nanowires as a potential means of supplying an earth abundant solution. The intrinsic anisotropy of a TiO2(110) substrate directs the growth of micron length iron wires at elevated temperatures, with a strong metal-support interaction giving rise to ilmenite (FeTiO3) encapsulation. Iron nanoparticles that decorate the nanowires display magnetic properties that suggest other possible applications.
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Affiliation(s)
- David
C. Grinter
- Department
of Chemistry and London Centre for Nanotechnology, University College London, London, WC1H 0AJ, U.K.
- Diamond
Light Source Ltd, Diamond House,
Harwell Science and Innovation Campus, Didcot, OX11 0DE, U.K.
| | - Bobbie-Jean A. Shaw
- Department
of Chemistry and London Centre for Nanotechnology, University College London, London, WC1H 0AJ, U.K.
| | - Chi L. Pang
- Department
of Chemistry and London Centre for Nanotechnology, University College London, London, WC1H 0AJ, U.K.
| | - Chi-Ming Yim
- Department
of Chemistry and London Centre for Nanotechnology, University College London, London, WC1H 0AJ, U.K.
| | | | - Charlotte A. Hall
- Diamond
Light Source Ltd, Diamond House,
Harwell Science and Innovation Campus, Didcot, OX11 0DE, U.K.
- Department
of Chemistry, University of Reading, Reading, RG6 6AD, U.K.
| | - Francesco Maccherozzi
- Diamond
Light Source Ltd, Diamond House,
Harwell Science and Innovation Campus, Didcot, OX11 0DE, U.K.
| | - Sarnjeet S. Dhesi
- Diamond
Light Source Ltd, Diamond House,
Harwell Science and Innovation Campus, Didcot, OX11 0DE, U.K.
| | - Masahiko Suzuki
- Fundamental
Electronics Research Institute, Osaka Electro-Communication
University, Neyagawa-shi, Osaka 572-8530, Japan
| | - Tsuneo Yasue
- Fundamental
Electronics Research Institute, Osaka Electro-Communication
University, Neyagawa-shi, Osaka 572-8530, Japan
| | - Takanori Koshikawa
- Fundamental
Electronics Research Institute, Osaka Electro-Communication
University, Neyagawa-shi, Osaka 572-8530, Japan
| | - Geoff Thornton
- Department
of Chemistry and London Centre for Nanotechnology, University College London, London, WC1H 0AJ, U.K.
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2
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Yim CM, Lamoureux PS, Mellor A, Pang CL, Idriss H, Pacchioni G, Thornton G. Size and Shape Dependence of the Electronic Structure of Gold Nanoclusters on TiO 2. J Phys Chem Lett 2021; 12:8363-8369. [PMID: 34432476 DOI: 10.1021/acs.jpclett.1c02167] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
Understanding the mechanism behind the superior catalytic power of single- or few-atom heterogeneous catalysts has become an important topic in surface chemistry. This is particularly the case for gold, with TiO2 being an efficient support. Here we use scanning tunneling microscopy/spectroscopy with theoretical calculations to investigate the adsorption geometry and local electronic structure of several-atom Au clusters on rutile TiO2(110), with the clusters fabricated by controlled manipulation of single atoms. Our study confirms that Au1 and Au2 clusters prefer adsorption at surface O vacancies. Au3 clusters adsorb at O vacancies in a linear-chain configuration parallel to the surface; in the absence of O vacancies they adsorb at Ti5c sites with a structure of a vertically pointing upright triangle. We find that both the electronic structure and cluster-substrate charge transfer depend critically on the cluster size, bonding configuration, and local environment. This suggests the possibility of engineering cluster selectivity for specific catalytic reactions.
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Affiliation(s)
- Chi-Ming Yim
- Department of Chemistry and London Centre for Nanotechnology, University College London, 20 Gordon Street, London WC1H 0AJ, U.K
| | - Philomena Schlexer Lamoureux
- Dipartimento di Scienza dei Materiali, Università degli Studi Milano-Bicocca, via R. Cozzi 55, 20126 Milano, Italy
| | - Andrew Mellor
- Department of Chemistry and London Centre for Nanotechnology, University College London, 20 Gordon Street, London WC1H 0AJ, U.K
| | - Chi L Pang
- Department of Chemistry and London Centre for Nanotechnology, University College London, 20 Gordon Street, London WC1H 0AJ, U.K
| | - Hicham Idriss
- Surface Science and Advanced Characterisation, Chemical Sciences Division, SABIC-CRD at KAUST, Thuwal 23955, Saudi Arabia
| | - Gianfranco Pacchioni
- Dipartimento di Scienza dei Materiali, Università degli Studi Milano-Bicocca, via R. Cozzi 55, 20126 Milano, Italy
| | - Geoff Thornton
- Department of Chemistry and London Centre for Nanotechnology, University College London, 20 Gordon Street, London WC1H 0AJ, U.K
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3
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Grinter DC, Allan M, Yang HJ, Salcedo A, Murgida GE, Shaw B, Pang CL, Idriss H, Ganduglia‐Pirovano MV, Thornton G. Ce=O Terminated CeO 2. Angew Chem Int Ed Engl 2021; 60:13835-13839. [PMID: 33826220 PMCID: PMC8251574 DOI: 10.1002/anie.202101771] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2021] [Revised: 04/06/2021] [Indexed: 02/02/2023]
Abstract
Multiply bonded lanthanide oxo groups are rare in coordination compounds and have not previously been reported for a surface termination of a lanthanide oxide. Here we report the observation of a Ce=O terminated ceria surface in a CeO2 (111)-( 3 × 3 )R30° reconstruction of ≈3 nm thick ceria islands prepared on Pt(111). This is evidenced by scanning tunnelling microscopy (STM), low energy electron diffraction (LEED) and high-resolution electron energy loss spectroscopy (HREELS) measurements in conjunction with density functional theory (DFT) calculations. A Ce=O stretching frequency of 775 cm-1 is observed in HREELS, compared with 766 cm-1 calculated by DFT. The calculations also predict that the Ce=O bond is weak, with an oxygen vacancy formation energy of 0.85 eV. This could play an important role in the facile removal of lattice oxygen from CeO2 , accompanied by the reduction of CeIV to CeIII , which is a key attribute of ceria-based systems in connection with their unique catalytic properties.
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Affiliation(s)
- David C. Grinter
- Department of Chemistry and London Centre for NanotechnologyUniversity College London20 Gordon StreetLondonWC1H 0AJUK
- Diamond Light SourceDiamond House, Harwell Science and Innovation CampusDidcotOX11 0DEUK
| | - Michael Allan
- Department of Chemistry and London Centre for NanotechnologyUniversity College London20 Gordon StreetLondonWC1H 0AJUK
| | - Hyun Jin Yang
- Department of Chemistry and London Centre for NanotechnologyUniversity College London20 Gordon StreetLondonWC1H 0AJUK
| | - Agustín Salcedo
- Departamento de Ingeniería Química, Facultad de IngenieríaUniversidad de Buenos AiresCiudad UniversitariaC1428EGABuenos AiresArgentina
| | - Gustavo E. Murgida
- Centro Atómico ConstituyentesGIyACNEASan MartínConsejo Nacional de Investigaciones Científicas y TecnicasC1033AAJBuenos AiresArgentina
| | - Bobbie‐Jean Shaw
- Department of Chemistry and London Centre for NanotechnologyUniversity College London20 Gordon StreetLondonWC1H 0AJUK
| | - Chi L. Pang
- Department of Chemistry and London Centre for NanotechnologyUniversity College London20 Gordon StreetLondonWC1H 0AJUK
| | - Hicham Idriss
- Department of Chemistry and London Centre for NanotechnologyUniversity College London20 Gordon StreetLondonWC1H 0AJUK
- Surface Science and Advanced CharacterisationChemical Sciences DivisionSABIC-CRD at KaustThuwal23955Saudi Arabia
| | | | - Geoff Thornton
- Department of Chemistry and London Centre for NanotechnologyUniversity College London20 Gordon StreetLondonWC1H 0AJUK
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4
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Grinter DC, Allan M, Yang HJ, Salcedo A, Murgida GE, Shaw B, Pang CL, Idriss H, Ganduglia‐Pirovano MV, Thornton G. Ce=O Terminated CeO
2. Angew Chem Int Ed Engl 2021. [DOI: 10.1002/ange.202101771] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Affiliation(s)
- David C. Grinter
- Department of Chemistry and London Centre for Nanotechnology University College London 20 Gordon Street London WC1H 0AJ UK
- Diamond Light Source Diamond House, Harwell Science and Innovation Campus Didcot OX11 0DE UK
| | - Michael Allan
- Department of Chemistry and London Centre for Nanotechnology University College London 20 Gordon Street London WC1H 0AJ UK
| | - Hyun Jin Yang
- Department of Chemistry and London Centre for Nanotechnology University College London 20 Gordon Street London WC1H 0AJ UK
| | - Agustín Salcedo
- Departamento de Ingeniería Química, Facultad de Ingeniería Universidad de Buenos Aires Ciudad Universitaria C1428EGA Buenos Aires Argentina
| | - Gustavo E. Murgida
- Centro Atómico Constituyentes GIyA CNEA San Martín Consejo Nacional de Investigaciones Científicas y Tecnicas C1033AAJ Buenos Aires Argentina
| | - Bobbie‐Jean Shaw
- Department of Chemistry and London Centre for Nanotechnology University College London 20 Gordon Street London WC1H 0AJ UK
| | - Chi L. Pang
- Department of Chemistry and London Centre for Nanotechnology University College London 20 Gordon Street London WC1H 0AJ UK
| | - Hicham Idriss
- Department of Chemistry and London Centre for Nanotechnology University College London 20 Gordon Street London WC1H 0AJ UK
- Surface Science and Advanced Characterisation Chemical Sciences Division SABIC-CRD at Kaust Thuwal 23955 Saudi Arabia
| | | | - Geoff Thornton
- Department of Chemistry and London Centre for Nanotechnology University College London 20 Gordon Street London WC1H 0AJ UK
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5
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Affiliation(s)
- C L Pang
- Royal London Hospital, Barts Health NHS Trust, London, UK
| | - M Gooneratne
- Royal London Hospital, Barts Health NHS Trust, London, UK
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6
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Mellor A, Wilson A, Pang CL, Yim CM, Maccherozzi F, Dhesi SS, Muryn CA, Idriss H, Thornton G. Photoemission core level binding energies from multiple sized nanoparticles on the same support: TiO 2(110)/Au. J Chem Phys 2020; 152:024709. [PMID: 31941300 DOI: 10.1063/1.5135760] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
A novel method of measuring the core level binding energies of multiple sized nanoparticles on the same substrate is demonstrated using the early stage of Au nanoparticle growth on reduced r-TiO2(110). This method employed in situ scanning tunneling microscopy (STM) and microfocused X-ray photoemission spectroscopy. An STM tip-shadowing method was used to synthesize patterned areas of Au nanoparticles on the substrate with different coverages and sizes. Patterns were identified and imaged using a UV photoelectron emission microscope. The Au 4f core level binding energies of the nanoparticles were investigated as a function of Au nanoparticle coverage and size. A combination of initial and final state effects modifies the binding energies of the Au 4f core levels as the nanoparticle size changes. When single Au atoms and Au3 clusters are present, the Au 4f7/2 binding energy, 84.42 eV, is similar to that observed at a high coverage (1.8 monolayer equivalent), resulting from a cancellation of initial and final state effects. As the coverage is increased, there is a decrease in binding energy, which then increases at a higher coverage to 84.39 eV. These results are consistent with a Volmer-Weber nucleation-growth model of Au nanoparticles at oxygen vacancies, resulting in electron transfer to the nanoparticles.
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Affiliation(s)
- Andrew Mellor
- Department of Chemistry and London Centre for Nanotechnology, University College London, 20 Gordon Street, London WC1H 0AJ, United Kingdom
| | - Axel Wilson
- Diamond Light Source, Harwell Science and Innovation Campus, Oxfordshire OX11 0DE, United Kingdom
| | - Chi L Pang
- Department of Chemistry and London Centre for Nanotechnology, University College London, 20 Gordon Street, London WC1H 0AJ, United Kingdom
| | - Chi M Yim
- Department of Chemistry and London Centre for Nanotechnology, University College London, 20 Gordon Street, London WC1H 0AJ, United Kingdom
| | - Francesco Maccherozzi
- Diamond Light Source, Harwell Science and Innovation Campus, Oxfordshire OX11 0DE, United Kingdom
| | - Sarnjeet S Dhesi
- Diamond Light Source, Harwell Science and Innovation Campus, Oxfordshire OX11 0DE, United Kingdom
| | - Christopher A Muryn
- School of Chemistry and Photon Science Institute, The University of Manchester, Oxford Road, Manchester M13 9PL, United Kingdom
| | - Hicham Idriss
- Department of Chemistry and London Centre for Nanotechnology, University College London, 20 Gordon Street, London WC1H 0AJ, United Kingdom
| | - Geoff Thornton
- Department of Chemistry and London Centre for Nanotechnology, University College London, 20 Gordon Street, London WC1H 0AJ, United Kingdom
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7
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Horner K, Barry S, Dave M, Dixon C, Littlewood A, Pang CL, Sengupta A, Srinivasan V. Diagnostic efficacy of cone beam computed tomography in paediatric dentistry: a systematic review. Eur Arch Paediatr Dent 2019; 21:407-426. [PMID: 31858481 PMCID: PMC7415745 DOI: 10.1007/s40368-019-00504-x] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2019] [Accepted: 12/10/2019] [Indexed: 01/08/2023]
Abstract
Purpose To determine in which clinical situations it is indicated or contra-indicated to prescribe cone beam computed tomography (CBCT) for paediatric patients. Methods Systematic review of in vivo paediatric research studies of diagnostic efficacy using CBCT, with supplementary searches for guideline documents on CBCT and for systematic reviews permitting inclusion of ex vivo and adult studies. Results After screening, 190 publications were included, mostly case studies. No systematic reviews were found of in vivo paediatric research. Fourteen studies of diagnostic efficacy were identified. The supplementary searches found 18 guideline documents relevant to the review and 26 systematic reviews. The diagnostic efficacy evidence on CBCT was diverse and often of limited quality. There was ex vivo evidence for diagnostic accuracy being greater using CBCT than radiographs for root fractures. The multiplanar capabilities of CBCT are advantageous when localising dental structures for surgical planning. Patient movement during scanning is more common in children which could reduce diagnostic efficacy. Conclusions No strong recommendations on CBCT are possible, except that it should not be used as a primary diagnostic tool for caries. Guidelines on use of CBCT in the paediatric age group should be developed cautiously, taking into account the greater radiation risk and the higher economic costs compared with radiography. CBCT should only be used when adequate conventional radiographic examination has not answered the question for which imaging was required. Clinical research in paediatric patients is required at the higher levels of diagnostic efficacy of CBCT. Electronic supplementary material The online version of this article (10.1007/s40368-019-00504-x) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- K Horner
- Division of Dentistry, School of Medical Sciences, Faculty of Biology, Medicine and Health, University of Manchester, Manchester Academic Health Science Centre, Coupland Building 3, Manchester, M13 9PL, UK.
- Dental Radiology, University Dental Hospital of Manchester, Manchester University NHS Foundation Trust, Manchester Academic Health Science Centre, Higher Cambridge Street, Manchester, M15 6FH, UK.
| | - S Barry
- Division of Dentistry, School of Medical Sciences, Faculty of Biology, Medicine and Health, University of Manchester, Manchester Academic Health Science Centre, Coupland Building 3, Manchester, M13 9PL, UK
- Paediatric Dentistry, University Dental Hospital of Manchester, Manchester University NHS Foundation Trust, Manchester Academic Health Science Centre, Higher Cambridge Street, Manchester, M15 6FH, UK
| | - M Dave
- Division of Dentistry, School of Medical Sciences, Faculty of Biology, Medicine and Health, University of Manchester, Manchester Academic Health Science Centre, Coupland Building 3, Manchester, M13 9PL, UK
| | - C Dixon
- Division of Dentistry, School of Medical Sciences, Faculty of Biology, Medicine and Health, University of Manchester, Manchester Academic Health Science Centre, Coupland Building 3, Manchester, M13 9PL, UK
- Paediatric Dentistry, University Dental Hospital of Manchester, Manchester University NHS Foundation Trust, Manchester Academic Health Science Centre, Higher Cambridge Street, Manchester, M15 6FH, UK
| | - A Littlewood
- Information Specialist, Cochrane Oral Health, Division of Dentistry, School of Medical Sciences, Faculty of Biology, Medicine and Health, University of Manchester, Manchester Academic Health Science Centre, Coupland Building 3, Manchester, M13 9PL, UK
| | - C L Pang
- Division of Imaging, Manchester Royal Infirmary, Manchester University NHS Foundation Trust, Manchester Academic Health Science Centre, Oxford Road, Manchester, M13 9WL, UK
| | - A Sengupta
- Division of Dentistry, School of Medical Sciences, Faculty of Biology, Medicine and Health, University of Manchester, Manchester Academic Health Science Centre, Coupland Building 3, Manchester, M13 9PL, UK
- Dental Radiology, University Dental Hospital of Manchester, Manchester University NHS Foundation Trust, Manchester Academic Health Science Centre, Higher Cambridge Street, Manchester, M15 6FH, UK
| | - V Srinivasan
- Paediatric Dentistry, University Dental Hospital of Manchester, Manchester University NHS Foundation Trust, Manchester Academic Health Science Centre, Higher Cambridge Street, Manchester, M15 6FH, UK
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8
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Zhang Y, Payne DT, Pang CL, Cacho C, Chapman RT, Springate E, Fielding HH, Thornton G. State-Selective Dynamics of TiO 2 Charge-Carrier Trapping and Recombination. J Phys Chem Lett 2019; 10:5265-5270. [PMID: 31434481 DOI: 10.1021/acs.jpclett.9b02153] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Time-resolved pump-probe photoemission spectroscopy has been used to study the dynamics of charge-carrier recombination and trapping on hydroxylated rutile TiO2(110). Two types of pump excitation were employed, one in the infrared (IR) (0.95 eV) and the other in the ultraviolet (UV) (3.5 eV) region. With IR excitation, electrons associated with defects are excited into the bottom of the conduction band from the polaronic states within the band gap, which are retrapped within 45 ± 10 fs. Under UV excitation, the electrons in these band-gap states (BGSs) and valence-band electrons are excited into the conduction band. In addition to the fast polaron trapping observed with IR excitation, we also observe a long lifetime (∼1 ps) component for both the depletion of hot electrons at the bottom of the conduction band and the refilling of the BGS. This points to a BGS-mediated recombination process with a picosecond lifetime.
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Affiliation(s)
- Yu Zhang
- Department of Chemistry, University College London, 20 Gordon Street, London WC1H 0AJ, United Kingdom
- London Centre for Nanotechnology, University College London, 17-19 Gordon Street, London WC1H 0AH, United Kingdom
- Central Laser Facility, STFC Rutherford Appleton Laboratory, Didcot OX11 0QX, United Kingdom
| | - Daniel T Payne
- Department of Chemistry, University College London, 20 Gordon Street, London WC1H 0AJ, United Kingdom
- London Centre for Nanotechnology, University College London, 17-19 Gordon Street, London WC1H 0AH, United Kingdom
| | - Chi L Pang
- Department of Chemistry, University College London, 20 Gordon Street, London WC1H 0AJ, United Kingdom
- London Centre for Nanotechnology, University College London, 17-19 Gordon Street, London WC1H 0AH, United Kingdom
| | - Cephise Cacho
- Central Laser Facility, STFC Rutherford Appleton Laboratory, Didcot OX11 0QX, United Kingdom
| | - Richard T Chapman
- Central Laser Facility, STFC Rutherford Appleton Laboratory, Didcot OX11 0QX, United Kingdom
| | - Emma Springate
- Central Laser Facility, STFC Rutherford Appleton Laboratory, Didcot OX11 0QX, United Kingdom
| | - Helen H Fielding
- Department of Chemistry, University College London, 20 Gordon Street, London WC1H 0AJ, United Kingdom
| | - Geoff Thornton
- Department of Chemistry, University College London, 20 Gordon Street, London WC1H 0AJ, United Kingdom
- London Centre for Nanotechnology, University College London, 17-19 Gordon Street, London WC1H 0AH, United Kingdom
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9
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Humphrey DS, Pang CL, Chen Q, Thornton G. Electron induced nanoscale engineering of rutile TiO 2 surfaces. Nanotechnology 2019; 30:025303. [PMID: 30411713 DOI: 10.1088/1361-6528/aae95b] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
Electron stimulated modifications of the rutile TiO2(110) surface have been investigated using scanning tunnelling microscopy tip pulses and electron beam irradiation. Tip pulses on the 'as-prepared' surface induce local surface reconstruction and removal of surface hydroxyls in a region around the reconstruction. A defocused beam from an electron gun as well as tip pulses have been used to generate a number of oxygen deficient surfaces. All tip pulse features display an oval profile, which can be attributed to the anisotropic conductivity of the TiO2(110) surface. A novel oxygen deficient phase with well-ordered defective 'nano-cracks' has been identified, which can be produced by either electron beam irradiation or low flash anneal temperatures (∼570 K). Annealing such surfaces to moderate temperatures (∼850 K) leads to mixed 1 × 1 and 1 × 2 surfaces, until now only achievable by annealing in oxygen or ageing by repeated sputter/anneal cycles. Heating to normal preparation temperatures (1000 K) reforms the clean, well-ordered 1 × 1 surface termination. Our results demonstrate the potential of electron induced processes to modify the oxygen composition and structure of the TiO2(110) surface in a controllable and reversible way for selective surface patterning and surface reactivity modification.
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Affiliation(s)
- David S Humphrey
- London Centre for Nanotechnology and Chemistry Department, University College London, 17-19 Gordon Street, London, WC1H 0AJ, United Kingdom
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10
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Yim CM, Chen J, Zhang Y, Shaw BJ, Pang CL, Grinter DC, Bluhm H, Salmeron M, Muryn CA, Michaelides A, Thornton G. Visualization of Water-Induced Surface Segregation of Polarons on Rutile TiO 2(110). J Phys Chem Lett 2018; 9:4865-4871. [PMID: 30081626 DOI: 10.1021/acs.jpclett.8b01904] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
Water-oxide surfaces are ubiquitous in nature and of widespread importance to phenomena like corrosion as well as contemporary industrial challenges such as energy production through water splitting. So far, a reasonably robust understanding of the structure of such interfaces under certain conditions has been obtained. Considerably less is known about how overlayer water modifies the inherent reactivity of oxide surfaces. Here we address this issue experimentally for rutile TiO2(110) using scanning tunneling microscopy and photoemission, with complementary density functional theory calculations. Through detailed studies of adsorbed water nanoclusters and continuous water overlayers, we determine that excess electrons in TiO2 are attracted to the top surface layer by water molecules. Measurements on methanol show similar behavior. Our results suggest that adsorbate-induced surface segregation of polarons could be a general phenomenon for technologically relevant oxide materials, with consequences for surface chemistry and the associated catalytic activity.
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Affiliation(s)
- Chi M Yim
- Department of Chemistry and London Centre for Nanotechnology , University College London , 20 Gordon Street , London WC1H 0AJ , United Kingdom
| | - Ji Chen
- Department of Physics and Astronomy, London Centre for Nanotechnology and Thomas Young Centre , University College London , London WC1E 6BT , United Kingdom
| | - Yu Zhang
- Department of Chemistry and London Centre for Nanotechnology , University College London , 20 Gordon Street , London WC1H 0AJ , United Kingdom
| | - Bobbie-Jean Shaw
- Department of Chemistry and London Centre for Nanotechnology , University College London , 20 Gordon Street , London WC1H 0AJ , United Kingdom
| | - Chi L Pang
- Department of Chemistry and London Centre for Nanotechnology , University College London , 20 Gordon Street , London WC1H 0AJ , United Kingdom
| | - David C Grinter
- Department of Chemistry and London Centre for Nanotechnology , University College London , 20 Gordon Street , London WC1H 0AJ , United Kingdom
| | - Hendrik Bluhm
- Chemical Sciences Division , Lawrence Berkeley National Laboratory , Berkeley , California 94720 , United States
- Advanced Light Source , Lawrence Berkeley National Laboratory , Berkeley , California 94720 , United States
| | - Miquel Salmeron
- Materials Science Division , Lawrence Berkeley National Laboratory , Berkeley , California 94720 , United States
| | - Christopher A Muryn
- School of Chemistry , The University of Manchester , Manchester M13 9PL , United Kingdom
| | - Angelos Michaelides
- Department of Physics and Astronomy, London Centre for Nanotechnology and Thomas Young Centre , University College London , London WC1E 6BT , United Kingdom
| | - Geoff Thornton
- Department of Chemistry and London Centre for Nanotechnology , University College London , 20 Gordon Street , London WC1H 0AJ , United Kingdom
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11
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Mellor A, Humphrey D, Yim CM, Pang CL, Idriss H, Thornton G. Direct Visualization of Au Atoms Bound to TiO 2(110) O-Vacancies. J Phys Chem C Nanomater Interfaces 2017; 121:24721-24725. [PMID: 29152035 PMCID: PMC5682598 DOI: 10.1021/acs.jpcc.7b09608] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 09/27/2017] [Revised: 10/17/2017] [Indexed: 06/07/2023]
Abstract
Au nanoparticles supported on reducible metal oxide surfaces are known to be active catalysts for a number of reactions including CO oxidation and hydrogen production. The exact choice of a metal oxide support has been shown to have a marked impact on activity, suggesting that interactions between Au and the support play a key role in catalysis. For TiO2, a model substrate for Au catalysis, it had been thought that bridging oxygen vacancies are involved in binding Au atoms to the (110) surface based on indirect evidence. However, a recent scanning transmission electron microscopy study of single Pt atoms on TiO2(110) suggests that subsurface vacancies are more important. To clarify the role of bridging or subsurface vacancies we employ scanning tunneling microscopy to determine the bonding site of single Au atoms on TiO2(110). Using in situ deposition as well as a manipulation method, we provide definitive evidence that the bonding site is atop surface oxygen vacancies.
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Affiliation(s)
- Andrew Mellor
- Department
of Chemistry and London Centre for Nanotechnology, University College London, 20 Gordon Street, London WC1H 0AJ, United Kingdom
| | - David Humphrey
- Department
of Chemistry and London Centre for Nanotechnology, University College London, 20 Gordon Street, London WC1H 0AJ, United Kingdom
| | - Chi M. Yim
- Department
of Chemistry and London Centre for Nanotechnology, University College London, 20 Gordon Street, London WC1H 0AJ, United Kingdom
| | - Chi L. Pang
- Department
of Chemistry and London Centre for Nanotechnology, University College London, 20 Gordon Street, London WC1H 0AJ, United Kingdom
| | - Hicham Idriss
- Department
of Chemistry and London Centre for Nanotechnology, University College London, 20 Gordon Street, London WC1H 0AJ, United Kingdom
- Fundamental
Catalysis, SABIC-CRI at KAUST, Thuwal, Saudi Arabia
| | - Geoff Thornton
- Department
of Chemistry and London Centre for Nanotechnology, University College London, 20 Gordon Street, London WC1H 0AJ, United Kingdom
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12
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Nadeem IM, Harrison GT, Wilson A, Pang CL, Zegenhagen J, Thornton G. Bridging Hydroxyls on Anatase TiO2(101) by Water Dissociation in Oxygen Vacancies. J Phys Chem B 2017; 122:834-839. [DOI: 10.1021/acs.jpcb.7b06955] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Immad M. Nadeem
- London
Centre for Nanotechnology and Department of Chemistry, University College London, 20 Gordon Street, London, WC1H 0AJ, U.K
- Diamond Light Source Ltd., Harwell Science and
Innovation Campus, Didcot, Oxfordshire, OX11 0DE, U.K
| | - George T. Harrison
- London
Centre for Nanotechnology and Department of Chemistry, University College London, 20 Gordon Street, London, WC1H 0AJ, U.K
| | - Axel Wilson
- London
Centre for Nanotechnology and Department of Chemistry, University College London, 20 Gordon Street, London, WC1H 0AJ, U.K
| | - Chi L. Pang
- London
Centre for Nanotechnology and Department of Chemistry, University College London, 20 Gordon Street, London, WC1H 0AJ, U.K
| | - Jörg Zegenhagen
- Diamond Light Source Ltd., Harwell Science and
Innovation Campus, Didcot, Oxfordshire, OX11 0DE, U.K
| | - Geoff Thornton
- London
Centre for Nanotechnology and Department of Chemistry, University College London, 20 Gordon Street, London, WC1H 0AJ, U.K
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13
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Hussain H, Tocci G, Woolcot T, Torrelles X, Pang CL, Humphrey DS, Yim CM, Grinter DC, Cabailh G, Bikondoa O, Lindsay R, Zegenhagen J, Michaelides A, Thornton G. Structure of a model TiO 2 photocatalytic interface. Nat Mater 2017; 16:461-466. [PMID: 27842073 DOI: 10.1038/nmat4793] [Citation(s) in RCA: 117] [Impact Index Per Article: 16.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/05/2015] [Accepted: 10/06/2016] [Indexed: 05/21/2023]
Abstract
The interaction of water with TiO2 is crucial to many of its practical applications, including photocatalytic water splitting. Following the first demonstration of this phenomenon 40 years ago there have been numerous studies of the rutile single-crystal TiO2(110) interface with water. This has provided an atomic-level understanding of the water-TiO2 interaction. However, nearly all of the previous studies of water/TiO2 interfaces involve water in the vapour phase. Here, we explore the interfacial structure between liquid water and a rutile TiO2(110) surface pre-characterized at the atomic level. Scanning tunnelling microscopy and surface X-ray diffraction are used to determine the structure, which is comprised of an ordered array of hydroxyl molecules with molecular water in the second layer. Static and dynamic density functional theory calculations suggest that a possible mechanism for formation of the hydroxyl overlayer involves the mixed adsorption of O2 and H2O on a partially defected surface. The quantitative structural properties derived here provide a basis with which to explore the atomistic properties and hence mechanisms involved in TiO2 photocatalysis.
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Affiliation(s)
- H Hussain
- London Centre for Nanotechnology and Department of Chemistry, University College London, 20 Gordon Street, London WC1H OAJ, UK
- ESRF, 6 rue Jules Horowitz, F-38000 Grenoble cedex, France
| | - G Tocci
- London Centre for Nanotechnology and Department of Chemistry, University College London, 20 Gordon Street, London WC1H OAJ, UK
| | - T Woolcot
- London Centre for Nanotechnology and Department of Chemistry, University College London, 20 Gordon Street, London WC1H OAJ, UK
| | - X Torrelles
- Institut de Ciència de Materials de Barcelona (CSIC), Campus UAB, 08193 Bellaterra, Spain
| | - C L Pang
- London Centre for Nanotechnology and Department of Chemistry, University College London, 20 Gordon Street, London WC1H OAJ, UK
| | - D S Humphrey
- London Centre for Nanotechnology and Department of Chemistry, University College London, 20 Gordon Street, London WC1H OAJ, UK
| | - C M Yim
- London Centre for Nanotechnology and Department of Chemistry, University College London, 20 Gordon Street, London WC1H OAJ, UK
| | - D C Grinter
- London Centre for Nanotechnology and Department of Chemistry, University College London, 20 Gordon Street, London WC1H OAJ, UK
| | - G Cabailh
- Sorbonne Universités, UPMC Univ Paris 06, CNRS-UMR 7588, Institut des NanoSciences de Paris, F-75005 Paris, France
| | - O Bikondoa
- Department of Physics, University of Warwick, Gibbet Hill Road, Coventry C4 7AL, UK
| | - R Lindsay
- Corrosion and Protection Centre, School of Materials, The University of Manchester, Sackville Street, Manchester M13 9PL, UK
| | - J Zegenhagen
- ESRF, 6 rue Jules Horowitz, F-38000 Grenoble cedex, France
| | - A Michaelides
- London Centre for Nanotechnology and Department of Chemistry, University College London, 20 Gordon Street, London WC1H OAJ, UK
| | - G Thornton
- London Centre for Nanotechnology and Department of Chemistry, University College London, 20 Gordon Street, London WC1H OAJ, UK
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14
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Yim CM, Watkins MB, Wolf MJ, Pang CL, Hermansson K, Thornton G. Engineering Polarons at a Metal Oxide Surface. Phys Rev Lett 2016; 117:116402. [PMID: 27661706 DOI: 10.1103/physrevlett.117.116402] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/04/2016] [Indexed: 06/06/2023]
Abstract
Polarons in metal oxides are important in processes such as catalysis, high temperature superconductivity, and dielectric breakdown in nanoscale electronics. Here, we study the behavior of electron small polarons associated with oxygen vacancies at rutile TiO_{2}(110), using a combination of low temperature scanning tunneling microscopy (STM), density functional theory, and classical molecular dynamics calculations. We find that the electrons are symmetrically distributed around isolated vacancies at 78 K, but as the temperature is reduced, their distributions become increasingly asymmetric, confirming their polaronic nature. By manipulating isolated vacancies with the STM tip, we show that particular configurations of polarons are preferred for given locations of the vacancies, which we ascribe to small residual electric fields in the surface. We also form a series of vacancy complexes and manipulate the Ti ions surrounding them, both of which change the associated electronic distributions. Thus, we demonstrate that the configurations of polarons can be engineered, paving the way for the construction of conductive pathways relevant to resistive switching devices.
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Affiliation(s)
- C M Yim
- Department of Chemistry and London Centre for Nanotechnology, University College London, 20 Gordon Street, London WC1H 0AJ, United Kingdom
| | - M B Watkins
- School of Mathematics and Physics, University of Lincoln, Brayford Pool, Lincoln LN6 7TS, United Kingdom
| | - M J Wolf
- Department of Physics & Astronomy and London Centre for Nanotechnology, University College London, Gower Street, London WC1E 6BT, United Kingdom
- Department of Chemistry, Ångström Laboratory, Uppsala University, Box 538, S-751 21 Uppsala, Sweden
| | - C L Pang
- Department of Chemistry and London Centre for Nanotechnology, University College London, 20 Gordon Street, London WC1H 0AJ, United Kingdom
| | - K Hermansson
- Department of Chemistry, Ångström Laboratory, Uppsala University, Box 538, S-751 21 Uppsala, Sweden
| | - G Thornton
- Department of Chemistry and London Centre for Nanotechnology, University College London, 20 Gordon Street, London WC1H 0AJ, United Kingdom
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15
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Abstract
Excess electrons facilitate redox reactions at the technologically relevant anatase TiO2(101) surface. The availability of these electrons is related to the defect concentration at the surface. We present two-photon (2PPE, 3.10–3.54 eV) and ultraviolet (UPS, 21.2 & 40.8 eV) photoemission spectroscopy measurements evidencing an increased concentration of excess electrons following electron bombardment at room temperature. Irradiation-induced surface oxygen vacancies are known to migrate into the sub-surface at this temperature, quickly equilibrating the surface defect concentration. Hence, we propose that the irradiated surface is hydroxylated. Peaks in UPS difference spectra are observed centred 8.45, 6.50 and 0.73 eV below the Fermi level, which are associated with the 3σ and 1π hydroxyl molecular orbitals and Ti 3d band gap states, respectively. The higher concentration of excess electrons at the hydroxylated anatase (101) surface may increase the potential for redox reactions.
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Affiliation(s)
- D T Payne
- 1Department of Chemistry, University College London, London, WC1H 0AJ UK.,2London Centre for Nanotechnology, University College London, London, WC1H 0AH UK
| | - Y Zhang
- 1Department of Chemistry, University College London, London, WC1H 0AJ UK.,2London Centre for Nanotechnology, University College London, London, WC1H 0AH UK
| | - C L Pang
- 1Department of Chemistry, University College London, London, WC1H 0AJ UK.,2London Centre for Nanotechnology, University College London, London, WC1H 0AH UK
| | - H H Fielding
- 1Department of Chemistry, University College London, London, WC1H 0AJ UK
| | - G Thornton
- 1Department of Chemistry, University College London, London, WC1H 0AJ UK.,2London Centre for Nanotechnology, University College London, London, WC1H 0AH UK
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16
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Pang CL. Invisible Visibility: Intergenerational Transfer of Identity and Social Position of Chinese Women in Belgium. Asian and Pacific Migration Journal 2016; 7:433-52. [PMID: 12295219 DOI: 10.1177/011719689800700402] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
The effects of migration on identity and the social position of Chinese women in Belgium were examined from an intergenerational perspective. At the macro level, policies and the general discourse on migration and migrants in Belgium were examined to assess the level of inclusion or exclusion of Chinese women. At the meso and micro levels, in-depth interviews suggest that the intergenerational transfer of identities and affiliations requires a significant amount of goodwill and ability to reinterpret and re-create adaptations that are acceptable to first and second-generation migrants. Social mobility among the first generation was mainly financial independence and autonomy, which opened up educational opportunities for their children. Those in the intermediate generation (those born in Hong Kong but who grew up in Belgium) realized that educational success was an important avenue for social mobility, particularly for daughters. In the patrilineal system of Chinese families, which persisted in Belgium, daughters are considered dependent members of the family and they have to fend for themselves if they want to be the author of their own life. The experience of a small number of successful Chinese female professionals supports this point. Presently, an increasing number of second-generation youngsters are attending school. They experience discrimination in varying degrees, suggesting that the othering process of Chinese females remains a problem in the realization of a truly pluralist society.
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17
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Abstract
The photochemistry of TiO2 has been studied intensively since it was discovered that TiO2 can act as a photocatalyst. Nevertheless, it has proven difficult to establish the detailed charge-transfer processes involved, partly because the excited states involved are difficult to study. Here we present evidence of the existence of hydroxyl-induced excited states in the conduction band region. Using two-photon photoemission, we show that stepwise photoexcitation from filled band gap states lying 0.8 eV below the Fermi level of rutile TiO2(110) excites hydroxyl-induced states 2.73 eV above the Fermi level that has an onset energy of ∼3.1 eV. The onset is shifted to lower energy by the coadsorption of molecular water, which suggests a means of tuning the energy of the excited state.
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Affiliation(s)
- Yu Zhang
- Department
of Chemistry, University College London, 20 Gordon Street, London WC1H 0AJ, United Kingdom
- London
Centre for Nanotechnology, University College
London, 17-19 Gordon
Street, London WC1H 0AH, United Kingdom
| | - Daniel T. Payne
- Department
of Chemistry, University College London, 20 Gordon Street, London WC1H 0AJ, United Kingdom
- London
Centre for Nanotechnology, University College
London, 17-19 Gordon
Street, London WC1H 0AH, United Kingdom
| | - Chi L. Pang
- Department
of Chemistry, University College London, 20 Gordon Street, London WC1H 0AJ, United Kingdom
- London
Centre for Nanotechnology, University College
London, 17-19 Gordon
Street, London WC1H 0AH, United Kingdom
| | - Helen
H. Fielding
- Department
of Chemistry, University College London, 20 Gordon Street, London WC1H 0AJ, United Kingdom
| | - Geoff Thornton
- Department
of Chemistry, University College London, 20 Gordon Street, London WC1H 0AJ, United Kingdom
- London
Centre for Nanotechnology, University College
London, 17-19 Gordon
Street, London WC1H 0AH, United Kingdom
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18
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Pang CL, Chanouzas D, Thomas M, Baharani J. Improving Acute Kidney Injury (AKI) outcomes through the use of automated electronic alerts. Eur J Intern Med 2015; 26:73. [PMID: 25457836 DOI: 10.1016/j.ejim.2014.10.011] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/01/2014] [Accepted: 10/08/2014] [Indexed: 11/22/2022]
Affiliation(s)
- C L Pang
- Heart of England NHS Foundation Trust, Birmingham, United Kingdom.
| | - D Chanouzas
- Heart of England NHS Foundation Trust, Birmingham, United Kingdom
| | - M Thomas
- Heart of England NHS Foundation Trust, Birmingham, United Kingdom
| | - J Baharani
- Heart of England NHS Foundation Trust, Birmingham, United Kingdom
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19
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Abstract
OBJECTIVES Despite many interventions that have been tried, controversy remains regarding the efficacy of interventions for contrast-induced nephropathy (CIN), so we aimed to evaluate the best evidence from recent meta-analyses. METHODS We searched MEDLINE, EMBASE and the Cochrane library for interventions which have been used for CIN. We included only the most recent meta-analysis of each intervention. We extracted data on the methodology, quality and results of each meta-analysis. We performed narrative synthesis and adjusted indirect comparison of interventions that were shown to be statistically significant compared with a placebo. RESULTS We included 7 systematic reviews and meta-analyses involving 9 different interventions for CIN, with a total of 15 976 participants. A significantly decreased risk of CIN was reported in meta-analysis of the following interventions: N-acetylcysteine [odds ratio (OR) 0.65, 95% confidence interval (CI) 0.48-0.88, I(2)=64%], theophylline [relative risk (RR) 0.48, 95% CI 0.26-0.89, I(2)=44%], statins (RR 0.51, 95% CI 0.34-0.77, I(2)=0%) and sodium bicarbonate (RR 0.62, 95% CI 0.45-0.86, I(2)=49%). Furosemide was shown to increase the risk of CIN (RR 3.27, 95% CI 1.48-7.26, I(2)=0%). Other interventions such as renal replacement therapy, angiotensin-converting enzyme inhibitors, dopamine and fenoldapam failed to show any significant difference from the control group. CONCLUSION Although there is some evidence to suggest that N-acetylcysteine, theophylline, sodium bicarbonate and statins may reduce incidence of CIN, limitations in the study quality and heterogeneity preclude any firm recommendations. ADVANCES IN KNOWLEDGE N-acetylcysteine, theophylline, sodium bicarbonate and statins show some promise as potentially efficacious agents for preventing CIN, but more high-quality studies are needed before they can be recommended for use in routine practice.
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Affiliation(s)
- C S Kwok
- Norfolk and Norwich University Hospital, Norwich, UK.
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20
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Woolcot T, Teobaldi G, Pang CL, Beglitis NS, Fisher AJ, Hofer WA, Thornton G. Scanning tunneling microscopy contrast mechanisms for TiO2. Phys Rev Lett 2012; 109:156105. [PMID: 23102341 DOI: 10.1103/physrevlett.109.156105] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/13/2012] [Revised: 08/26/2012] [Indexed: 05/20/2023]
Abstract
Controlled dual mode scanning tunneling microscopy (STM) experiments and first-principles simulations show that the tunneling conditions can significantly alter the positive-bias topographic contrast of geometrically corrugated titania surfaces such as rutile TiO2(011)-(2×1). Depending on the tip-surface distance, two different contrasts can be reversibly imaged. STM simulations which either include or neglect the tip-electronic structure, carried out at three density functional theory levels of increasing accuracy, allow assignment of both contrasts on the basis of the TiO2(011)-(2×1) structure proposed by Torrelles et al. [Phys. Rev. Lett. 101, 185501 (2008)]. Finally, the mechanisms of contrast formation are elucidated in terms of the subtle balance between the surface geometry and the different vacuum decay lengths of the topmost Ti(3d) and O(2p) states probed by the STM-tip apex.
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Affiliation(s)
- T Woolcot
- London Centre for Nanotechnology, London, United Kingdom
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21
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Abstract
Scanning tunneling microscopy and photoemission spectroscopy have been used to determine the origin of the band-gap state in rutile TiO2(110). This state has long been attributed to oxygen vacancies (O{b} vac). However, recently an alternative origin has been suggested, namely, subsurface interstitial Ti species. Here, we use electron bombardment to vary the O{b} vac density while monitoring the band-gap state with photoemission spectroscopy. Our results show that O{b} vac make the dominant contribution to the photoemission peak and that its magnitude is directly proportional to the O{b} vac density.
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Affiliation(s)
- C M Yim
- London Centre for Nanotechnology and Department of Chemistry, University College London, 17-19 Gordon Street, London WC1H 0AH, United Kingdom
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22
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Humphrey DS, Cabailh G, Pang CL, Muryn CA, Cavill SA, Marchetto H, Potenza A, Dhesi SS, Thornton G. Self-assembled metallic nanowires on a dielectric support: Pd on rutile TiO2(110). Nano Lett 2009; 9:155-159. [PMID: 19113893 DOI: 10.1021/nl802703e] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
Palladium nanoparticles supported on rutile TiO(2)(110)-1 x 1 have been studied using the complementary techniques of scanning tunneling microscopy and X-ray photoemission electron microscopy. Two distinct types of palladium nanoparticles are observed, namely long nanowires up to 1000 nm long, and smaller dotlike features with diameters ranging from 80-160 nm. X-ray photoemission electron microscopy reveals that the nanoparticles are composed of metallic palladium, separated by the bare TiO(2)(110) surface.
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Affiliation(s)
- David S Humphrey
- London Centre for Nanotechnology and Department of Chemistry, University College London, London WC1H 0AJ, United Kingdom
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23
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Abstract
Reduced phases of ultrathin rutile TiO(2)(110) grown on Ni(110) have been characterized with scanning tunneling microscopy and low-energy electron diffraction. Areas of 1 x 2 reconstruction are observed as well as {132} and {121} families of crystallographic shear planes. These phases are assigned by comparison with analogous phases on native rutile TiO(2)(110).
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Affiliation(s)
- Anthoula C Papageorgiou
- London Centre for Nanotechnology and Chemistry Department, University College London, 17-19 Gordon Street, London WC1H 0AH, UK
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