51
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Zeuthen H, Kudernatsch W, Merte LR, Ono LK, Lammich L, Besenbacher F, Wendt S. Unraveling the edge structures of platinum(111)-supported ultrathin FeO islands: the influence of oxidation state. ACS NANO 2015; 9:573-583. [PMID: 25574971 DOI: 10.1021/nn505890v] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
We used high-resolution scanning tunneling microscopy to study the structure of ultrathin FeO islands grown on Pt(111). Our focus is particularly on the edges of the FeO islands that are important in heterogeneous catalysis, as they host the active sites on inversed catalysts. To imitate various reaction environments we studied pristine, oxidized, and reduced FeO islands. Oxidation of the FeO islands by O2 exposure led to the formation of two types of O adatom dislocations and to a restructuring of the FeO islands, creating long O-rich edges and few short Fe-terminated edges. In contrast, reducing the FeO islands led to a dominance of Fe-rich edges and the occurrence of few and short O-rich edges. In addition, for reducing conditions we observed the formation of O vacancy dislocations on the FeO islands. Through the identification of O adatom and O vacancy dislocations known from closed ultrathin FeO films and geometrical considerations we unraveled the atomic structure of the predominant FeO boundaries of pristine, oxidized, and reduced FeO islands. The results indicate an astonishing flexibility of the FeO islands on Pt(111), since the predominant edge termination and the island shape depend strongly on the preparation conditions.
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Affiliation(s)
- Helene Zeuthen
- Interdisciplinary Nanoscience Center (iNANO) and Department of Physics and Astronomy, Aarhus University , DK-8000 Aarhus C, Denmark
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52
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Nguyen TD, Dinh CT, Do TO. Tailoring the assembly, interfaces, and porosity of nanostructures toward enhanced catalytic activity. Chem Commun (Camb) 2015; 51:624-35. [DOI: 10.1039/c4cc05741d] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The evolution of nanotechnology has inspired materials scientists to invent nanostructures with achievements in numerous practical applications, particularly in catalysis.
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Affiliation(s)
| | - Cao-Thang Dinh
- Department of Chemical Engineering
- Laval University
- Quebec
- Canada
| | - Trong-On Do
- Department of Chemical Engineering
- Laval University
- Quebec
- Canada
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53
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Gubó R, Óvári L, Kónya Z, Berkó A. Growth of Gold on a Pinwheel TiO∼1.2 Encapsulation Film Prepared on Rhodium Nanocrystallites. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2014; 30:14545-54. [PMID: 25417893 DOI: 10.1021/la503756c] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Affiliation(s)
- R. Gubó
- Department
of Applied and Environmental Chemistry, University of Szeged, 6720 Szeged, Rerrich Béla tér
1, Hungary
| | - L. Óvári
- MTA-SZTE Reaction
Kinetics and Surface Chemistry Research Group, 6720 Szeged, Rerrich Béla
tér 1, Hungary
| | - Z. Kónya
- Department
of Applied and Environmental Chemistry, University of Szeged, 6720 Szeged, Rerrich Béla tér
1, Hungary
- MTA-SZTE Reaction
Kinetics and Surface Chemistry Research Group, 6720 Szeged, Rerrich Béla
tér 1, Hungary
| | - A. Berkó
- MTA-SZTE Reaction
Kinetics and Surface Chemistry Research Group, 6720 Szeged, Rerrich Béla
tér 1, Hungary
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54
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Wang Y, Zhang X, Luo Z, Huang X, Tan C, Li H, Zheng B, Li B, Huang Y, Yang J, Zong Y, Ying Y, Zhang H. Liquid-phase growth of platinum nanoparticles on molybdenum trioxide nanosheets: an enhanced catalyst with intrinsic peroxidase-like catalytic activity. NANOSCALE 2014; 6:12340-4. [PMID: 25188584 DOI: 10.1039/c4nr04115a] [Citation(s) in RCA: 45] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/08/2023]
Abstract
A facile method for the synthesis of metal nanostructure-decorated two-dimensional (2D) semiconductor nanosheets was developed. The solution-processable molybdenum trioxide (MoO3) nanosheet was used as a template for direct liquid-phase growth of platinum nanoparticles (Pt NPs) under ambient conditions. Results show that the Pt NPs with sizes of 1-3 nm were uniformly grown on the MoO3 surface. Importantly, the Pt-MoO3 hybrid nanomaterial exhibits an enhanced peroxidase-like catalytic activity compared to the MoO3 nanosheet, Pt NPs, and their physical mixture under the same conditions. As a proof-of-concept application, the Pt-MoO3 hybrid nanomaterial was used as a high-efficiency peroxidase-mimic for ultrasensitive colorimetric detection of glucose in serum samples. This work provides a promising strategy for design and development of biomimetic catalysts by smart assembly of different dimensional nanomaterials.
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Affiliation(s)
- Yixian Wang
- School of Materials Science and Engineering, Nanyang Technological University, 50 Nanyang Avenue, Singapore 639798, Singapore.
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55
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Prada S, Giordano L, Pacchioni G, Noguera C, Goniakowski J. Properties of Pt-supported iron oxide ultra-thin films: Similarity of Hubbard-corrected and hybrid density functional theory description. J Chem Phys 2014; 141:144702. [DOI: 10.1063/1.4897196] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
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56
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Steurer W, Surnev S, Netzer FP, Sementa L, Negreiros FR, Barcaro G, Durante N, Fortunelli A. Redox processes at a nanostructured interface under strong electric fields. NANOSCALE 2014; 6:10589-10595. [PMID: 25075914 DOI: 10.1039/c4nr02882a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
Manipulation of chemistry and film growth via external electric fields is a longstanding goal in surface science. Numerous systems have been predicted to show such effects but experimental evidence is sparse. Here we demonstrate in a custom-designed UHV apparatus that the application of spatially extended, homogeneous, very high (>1 V nm(-1)) DC-fields not only changes the system energetics but triggers dynamic processes which become important much before static contributions appreciably modify the potential energy landscape. We take a well characterized ultrathin NiO film on a Ag(100) support as a proof-of-principle test case, and show how it gets reduced to supported Ni clusters under fields exceeding the threshold of +0.9 V nm(-1). Using an effective model, we trace the observed interfacial redox process down to a dissociative electron attachment resonant mechanism. The proposed approach can be easily implemented and generally applied to a wide range of interfacial systems, thus opening new opportunities for the manipulation of film growth and reaction processes at solid surfaces under strong external fields.
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Affiliation(s)
- Wolfram Steurer
- Surface and Interface Physics, Institute of Physics, Karl-Franzens University Graz, A-8010 Graz, Austria
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57
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Hierarchical synthesis of non-centrosymmetric hybrid nanostructures and enabled plasmon-driven photocatalysis. Nat Commun 2014; 5:4792. [DOI: 10.1038/ncomms5792] [Citation(s) in RCA: 94] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2014] [Accepted: 07/24/2014] [Indexed: 11/08/2022] Open
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58
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Rajesh C, Nigam S, Majumder C. The structural and electronic properties of Aunclusters on the α-Al2O3(0001) surface: a first principles study. Phys Chem Chem Phys 2014; 16:26561-9. [DOI: 10.1039/c4cp02137a] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
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59
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Negreiros FR, Barcaro G, Sementa L, Fortunelli A. Concepts in theoretical heterogeneous ultrananocatalysis. CR CHIM 2014. [DOI: 10.1016/j.crci.2013.12.008] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
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60
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Óvári L, Berkó A, Gubó R, Rácz Á, Kónya Z. Effect of a Gold Cover Layer on the Encapsulation of Rhodium by Titanium Oxides on Titanium Dioxide(110). THE JOURNAL OF PHYSICAL CHEMISTRY C 2014. [DOI: 10.1021/jp502748a] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- László Óvári
- MTA-SZTE Reaction Kinetics
and Surface Chemistry Research Group, Rerrich Béla tér 1, H-6720 Szeged, Hungary
| | - András Berkó
- MTA-SZTE Reaction Kinetics
and Surface Chemistry Research Group, Rerrich Béla tér 1, H-6720 Szeged, Hungary
| | - Richárd Gubó
- Department of Applied
and Environmental Chemistry, University of Szeged, Rerrich Béla
tér 1, H-6720 Szeged, Hungary
| | - Árpád Rácz
- Department of Applied
and Environmental Chemistry, University of Szeged, Rerrich Béla
tér 1, H-6720 Szeged, Hungary
| | - Zoltán Kónya
- MTA-SZTE Reaction Kinetics
and Surface Chemistry Research Group, Rerrich Béla tér 1, H-6720 Szeged, Hungary
- Department of Applied
and Environmental Chemistry, University of Szeged, Rerrich Béla
tér 1, H-6720 Szeged, Hungary
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61
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Denk M, Kuhness D, Wagner M, Surnev S, Negreiros FR, Sementa L, Barcaro G, Vobornik I, Fortunelli A, Netzer FP. Metal tungstates at the ultimate two-dimensional limit: fabrication of a CuWO₄ nanophase. ACS NANO 2014; 8:3947-54. [PMID: 24617647 DOI: 10.1021/nn500867y] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/21/2023]
Abstract
Metal tungstates (with general formula MWO4) are functional materials with a high potential for a diverse set of applications ranging from low-dimensional magnetism to chemical sensing and photoelectrocatalytic water oxidation. For high level applications, nanoscale control of film growth is necessary, as well as a deeper understanding and characterization of materials properties at reduced dimensionality. We succeeded in fabricating and characterizing a two-dimensional (2-D) copper tungstate (CuWO4). For the first time, the atomic structure of an ultrathin ternary oxide is fully unveiled. It corresponds to a CuWO4 monolayer arranged in three sublayers with stacking O-W-O/Cu from the interface. The resulting bidimensional structure forms a robust framework with localized regions of anisotropic flexibility. Electronically it displays a reduced band gap and increased density of states close to the Fermi level with respect to the bulk compound. These unique features open a way for new applications in the field of photo- and electrocatalysis, while the proposed synthesis method represents a radically new and general approach toward the fabrication of 2-D ternary oxides.
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Affiliation(s)
- Martin Denk
- Surface and Interface Physics, Institute of Physics, Karl-Franzens University A-8010 Graz, Austria
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62
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Agnoli S, Reeder AE, Senanayake SD, Hrbek J, Rodriguez JA. Structure and special chemical reactivity of interface-stabilized cerium oxide nanolayers on TiO2(110). NANOSCALE 2014; 6:800-810. [PMID: 24257903 DOI: 10.1039/c3nr04623k] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
Novel interface-stabilized ceria nanophases have been grown on TiO2(110) by physical vapor deposition. At low coverage, dumbbell nanostructures constituted by reconstructed titania and ceria clusters are formed, while long range ordered nanoxides can be obtained by increasing the ceria dose. Scanning tunneling microscopy and photoemission spectroscopy were used to characterize the electronic properties of the films, showing that the TiO2 substrate can effectively stabilize ceria in reduced form over a wide range of experimental conditions. Epitaxial coupling is a very useful tool for tuning the chemical properties of mixed oxide systems. The special electronic properties of the films have a direct counterpart in the chemical activity, which has been investigated by temperature programmed desorption using methanol as a probe molecule. The experimental results indicate an exceptional activity of the ceria-titania interface in the selective dehydration of methanol to formaldehyde at an unprecedented low temperature (330 K).
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Affiliation(s)
- Stefano Agnoli
- Department of Chemical Sciences, University of Padova, Via F. Marzolo 1, 35131 Padova, Italy.
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63
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64
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Berkó A, Gubó R, Óvári L, Bugyi L, Szenti I, Kónya Z. Interaction of Rh with Rh Nanoparticles Encapsulated by Ordered Ultrathin TiO1+x Film on TiO2(110) Surface. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2013; 29:15868-77. [PMID: 24299464 DOI: 10.1021/la4038292] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Affiliation(s)
- A. Berkó
- MTA-SZTE
Reaction Kinetics and Surface Chemistry Research Group, 6720 Szeged, Rerrich Béla tér 1, Hungary
| | - R. Gubó
- Department
of Applied and Enviromental Chemistry, University of Szeged, Rerrich Béla
tér 1, 6720 Szeged, Hungary
| | - L. Óvári
- MTA-SZTE
Reaction Kinetics and Surface Chemistry Research Group, 6720 Szeged, Rerrich Béla tér 1, Hungary
| | - L. Bugyi
- MTA-SZTE
Reaction Kinetics and Surface Chemistry Research Group, 6720 Szeged, Rerrich Béla tér 1, Hungary
| | - I. Szenti
- Department
of Applied and Enviromental Chemistry, University of Szeged, Rerrich Béla
tér 1, 6720 Szeged, Hungary
| | - Z. Kónya
- MTA-SZTE
Reaction Kinetics and Surface Chemistry Research Group, 6720 Szeged, Rerrich Béla tér 1, Hungary
- Department
of Applied and Enviromental Chemistry, University of Szeged, Rerrich Béla
tér 1, 6720 Szeged, Hungary
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65
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Xu X, Fu Q, Guo X, Bao X. A Highly Active “NiO-on-Au” Surface Architecture for CO Oxidation. ACS Catal 2013. [DOI: 10.1021/cs400197t] [Citation(s) in RCA: 55] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Xuejun Xu
- State Key Laboratory of Catalysis,
Dalian Institute
of Chemical Physics, Chinese Academy of Sciences, Dalian 116023, China
| | - Qiang Fu
- State Key Laboratory of Catalysis,
Dalian Institute
of Chemical Physics, Chinese Academy of Sciences, Dalian 116023, China
| | - Xiaoguang Guo
- State Key Laboratory of Catalysis,
Dalian Institute
of Chemical Physics, Chinese Academy of Sciences, Dalian 116023, China
| | - Xinhe Bao
- State Key Laboratory of Catalysis,
Dalian Institute
of Chemical Physics, Chinese Academy of Sciences, Dalian 116023, China
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66
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Jaouen T, Tricot S, Delhaye G, Lépine B, Sébilleau D, Jézéquel G, Schieffer P. Layer-resolved study of Mg atom incorporation at the MgO/Ag(001) buried interface. PHYSICAL REVIEW LETTERS 2013; 111:027601. [PMID: 23889444 DOI: 10.1103/physrevlett.111.027601] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/10/2013] [Indexed: 06/02/2023]
Abstract
By combining x-ray excited Auger electron diffraction experiments and multiple scattering calculations we reveal a layer-resolved shift for the Mg KL23L23 Auger transition in MgO ultrathin films (4-6 Å) on Ag(001). This resolution is exploited to demonstrate the possibility of controlling Mg atom incorporation at the MgO/Ag(001) interface by exposing the MgO films to a Mg flux. A substantial reduction of the MgO/Ag(001) work function is observed during the exposition phase and reflects both band-offset variations at the interface and band bending effects in the oxide film.
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Affiliation(s)
- T Jaouen
- Département de Physique and Fribourg Center for Nanomaterials, Université de Fribourg, CH-1700 Fribourg, Switzerland.
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67
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Fu Q, Yao Y, Guo X, Wei M, Ning Y, Liu H, Yang F, Liu Z, Bao X. Reversible structural transformation of FeOx nanostructures on Pt under cycling redox conditions and its effect on oxidation catalysis. Phys Chem Chem Phys 2013; 15:14708-14. [DOI: 10.1039/c3cp52587b] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
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