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Zhu Q, Adachi Y, Wen H, Xu R, Cheng Z, Sugawara Y, Li Y. Charge State of Au Atoms on an Oxidized Rutile TiO 2(110) Surface by AFM/KPFM at 78 K. Langmuir 2024; 40:1358-1363. [PMID: 38174984 DOI: 10.1021/acs.langmuir.3c02999] [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: 01/05/2024]
Abstract
The charge state of noble metal atoms on a semiconductor surface is an important factor in surface catalysis. In this study, Au atoms were deposited on the rutile TiO2(110) surface to characterize its charge properties using atomic force microscopy with Kelvin probe force microscopy at 78 K. Au single atoms, dimers, and trimers at different sites on the surface were investigated. Positively charged Au atoms were verified at oxygen sites, while negatively charged Au atoms were found near oxygen vacancy sites. Furthermore, the charge states of small Au nanoclusters were clarified. Understanding the charge states of Au atoms is significant for identifying their efficient catalytic effects in surface catalysis.
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Affiliation(s)
- Qiang Zhu
- Department of Applied Physics, Graduate School of Engineering, Osaka University, 2-1 Yamadaoka, Suita, Osaka 5650871, Japan
| | - Yuuki Adachi
- Department of Applied Physics, Graduate School of Engineering, Osaka University, 2-1 Yamadaoka, Suita, Osaka 5650871, Japan
| | - Huanfei Wen
- Key Laboratory of Instrumentation Science and Dynamic Measurement, School of Instrument and Electronics, North University of China, Taiyuan, Shanxi 030051, People's Republic of China
| | - Rui Xu
- Beijing Key Laboratory of Optoelectronic Functional Materials & Micro-nano Devices, Department of Physics, Renmin University of China, Beijing 100872, People's Republic of China
| | - Zhihai Cheng
- Beijing Key Laboratory of Optoelectronic Functional Materials & Micro-nano Devices, Department of Physics, Renmin University of China, Beijing 100872, People's Republic of China
| | - Yasuhiro Sugawara
- Department of Applied Physics, Graduate School of Engineering, Osaka University, 2-1 Yamadaoka, Suita, Osaka 5650871, Japan
| | - Yanjun Li
- Department of Applied Physics, Graduate School of Engineering, Osaka University, 2-1 Yamadaoka, Suita, Osaka 5650871, Japan
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Adachi Y, Brndiar J, Konôpka M, Turanský R, Zhu Q, Wen HF, Sugawara Y, Kantorovich L, Štich I, Li YJ. Tip-activated single-atom catalysis: CO oxidation on Au adatom on oxidized rutile TiO 2 surface. Sci Adv 2023; 9:eadi4799. [PMID: 37756403 PMCID: PMC10530063 DOI: 10.1126/sciadv.adi4799] [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] [Received: 04/27/2023] [Accepted: 08/25/2023] [Indexed: 09/29/2023]
Abstract
Single-atom catalysis of carbon monoxide oxidation on metal-oxide surfaces is crucial for greenhouse recycling, automotive catalysis, and beyond, but reports of the atomic-scale mechanism are still scarce. Here, using scanning probe microscopy, we show that charging single gold atoms on oxidized rutile titanium dioxide surface, both positively and negatively, considerably promotes adsorption of carbon monoxide. No carbon monoxide adsorption is observed on neutral gold atoms. Two different carbon monoxide adsorption geometries on gold atoms are identified. We demonstrate full control over the redox state of adsorbed gold single atoms, carbon monoxide adsorption geometry, and carbon monoxide adsorption/desorption by the atomic force microscopy tip. On charged gold atoms, we activate Eley-Rideal oxidation reaction between carbon monoxide and a neighboring oxygen adatom by the tip. Our results provide unprecedented insights into carbon monoxide adsorption and suggest that the gold dual activity for carbon monoxide oxidation after electron or hole attachment is also the key ingredient in photocatalysis under realistic conditions.
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Affiliation(s)
- Yuuki Adachi
- Department of Applied Physics, Osaka University, 2-1 Yamadaoka, Suita, Osaka 565-0871, Japan
| | - Ján Brndiar
- Institute of Informatics, Slovak Academy of Sciences, 845 07 Bratislava, Slovakia
| | - Martin Konôpka
- Faculty of Electrical Engineering and Information Technology, Institute of Nuclear and Physical Engineering, Slovak University of Technology in Bratislava, 812 19 Bratislava, Slovakia
| | - Robert Turanský
- Institute of Physics, Slovak Academy of Sciences, 845 11 Bratislava, Slovakia
| | - Qiang Zhu
- Department of Applied Physics, Osaka University, 2-1 Yamadaoka, Suita, Osaka 565-0871, Japan
| | - Huan Fei Wen
- Key Laboratory of Instrumentation Science and Dynamic Measurement, School of Instrument and Electronics, North University of China, Taiyuan, Shanxi 030051, China
| | - Yasuhiro Sugawara
- Department of Applied Physics, Osaka University, 2-1 Yamadaoka, Suita, Osaka 565-0871, Japan
| | - Lev Kantorovich
- Department of Physics, School of Natural and Mathematical Sciences, King’s College London, The Strand, London WC2R 2LS, UK
| | - Ivan Štich
- Institute of Informatics, Slovak Academy of Sciences, 845 07 Bratislava, Slovakia
- Institute of Physics, Slovak Academy of Sciences, 845 11 Bratislava, Slovakia
- Faculty of Natural Sciences, University of Ss. Cyril and Methodius, 917 01 Trnava, Slovakia
| | - Yan Jun Li
- Department of Applied Physics, Osaka University, 2-1 Yamadaoka, Suita, Osaka 565-0871, Japan
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Qu Z, Sugawara Y, Li Y. Investigation of semiconductor properties of Co/Si(111)-7 × 7 by AFM/KPFS. J Phys Condens Matter 2023; 35:185001. [PMID: 36848678 DOI: 10.1088/1361-648x/acbf93] [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] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/06/2023] [Accepted: 02/27/2023] [Indexed: 06/18/2023]
Abstract
Studies of the physics underlying carrier transport characteristics and band bending of semiconductors are critical for developing new types of devices. In this work, we investigated the physical properties of Co ring-like cluster (RC) reconstruction with a low Co coverage on a Si(111)-7 × 7 surface at atomic resolution by atomic force microscopy/Kelvin probe force microscopy at 78 K. We compared the applied bias dependence of frequency shift between two types of structure: Si(111)-7 × 7 and Co-RC reconstructions. As a result, the accumulation, depletion, and reversion layers were identified in the Co-RC reconstruction by bias spectroscopy. For the first time, we found that Co-RC reconstruction on the Si(111)-7 × 7 surface shows semiconductor properties by Kelvin probe force spectroscopy. The findings of this study are useful for developing new materials for semiconductor devices.
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Affiliation(s)
- Zhang Qu
- Department of Applied Physics, Graduate School of Engineering, Osaka University, 2-1 Yamadaoka, Suita, Osaka 565-0871, Japan
| | - Yasuhiro Sugawara
- Department of Applied Physics, Graduate School of Engineering, Osaka University, 2-1 Yamadaoka, Suita, Osaka 565-0871, Japan
| | - Yanjun Li
- Department of Applied Physics, Graduate School of Engineering, Osaka University, 2-1 Yamadaoka, Suita, Osaka 565-0871, Japan
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4
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Zhu Q, Sugawara Y, Li Y. Exploration of CO movement characteristics on rutile TiO2(110) surface. Colloids Surf A Physicochem Eng Asp 2023. [DOI: 10.1016/j.colsurfa.2022.130402] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
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Li F, Wang B, Chen X, Lai Y, Wang T, Fan H, Yang X, Guo Q. Photocatalytic Oxidative Dehydrogenation of Propane for Selective Propene Production with TiO 2. JACS Au 2022; 2:2607-2616. [PMID: 36465539 PMCID: PMC9709955 DOI: 10.1021/jacsau.2c00512] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/16/2022] [Revised: 10/15/2022] [Accepted: 10/17/2022] [Indexed: 06/17/2023]
Abstract
Oxidative dehydrogenation of propane (ODHP) as an exothermic process is a promising method to produce propene (C3H6) with lower energy consumption in chemical industry. However, the selectivity of the C3H6 product is always poor because of overoxidation. Herein, the ODHP reaction into C3H6 on a model rutile(R)-TiO2(110) surface at low temperature via photocatalysis has been realized successfully. The results illustrate that photocatalytic oxidative dehydrogenation of propane (C3H8) into C3H6 can occur efficiently on R-TiO2(110) at 90 K via a stepwise manner, in which the initial C-H cleavage occurs via the hole coupled C-H bond cleavage pathway followed by a radical mediated C-H cleavage to the C3H6 product. An exceptional selectivity of ∼90% for C3H6 production is achieved at about 13% propane conversion. The mechanistic model constructed in this study not only advances our understanding of C-H bond activation but also provides a new pathway for highly selective ODHP into C3H6 under mild conditions.
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Affiliation(s)
- Fangliang Li
- Shenzhen
Key Laboratory of Energy Chemistry & Department of Chemistry, Southern University of Science and Technology, Shenzhen, Guangdong518055, P. R. China
| | - Binli Wang
- Shenzhen
Institute of Advanced Technology, Chinese Academy of Sciences, Shenzhen, Guangdong518055, P. R. China
| | - Xiao Chen
- Shenzhen
Key Laboratory of Energy Chemistry & Department of Chemistry, Southern University of Science and Technology, Shenzhen, Guangdong518055, P. R. China
| | - Yuemiao Lai
- Shenzhen
Key Laboratory of Energy Chemistry & Department of Chemistry, Southern University of Science and Technology, Shenzhen, Guangdong518055, P. R. China
| | - Tao Wang
- Shenzhen
Key Laboratory of Energy Chemistry & Department of Chemistry, Southern University of Science and Technology, Shenzhen, Guangdong518055, P. R. China
| | - Hongjun Fan
- State
Key Laboratory of Molecular Reaction Dynamics, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian, Liaoning116023, P. R. China
| | - Xueming Yang
- Shenzhen
Key Laboratory of Energy Chemistry & Department of Chemistry, Southern University of Science and Technology, Shenzhen, Guangdong518055, P. R. China
- State
Key Laboratory of Molecular Reaction Dynamics, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian, Liaoning116023, P. R. China
- Hefei
National Laboratory, Hefei230088, P. R. China
| | - Qing Guo
- Shenzhen
Key Laboratory of Energy Chemistry & Department of Chemistry, Southern University of Science and Technology, Shenzhen, Guangdong518055, P. R. China
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Izumi R, Li YJ, Naitoh Y, Sugawara Y. Study of High-Low KPFM on a pn-Patterned Si Surface. Microscopy (Oxf) 2022; 71:98-103. [PMID: 35018450 PMCID: PMC8973402 DOI: 10.1093/jmicro/dfab055] [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] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2021] [Revised: 11/30/2021] [Accepted: 03/23/2022] [Indexed: 11/15/2022] Open
Abstract
Comparative measurements between frequency modulation Kelvin probe force microscopy (FM-KPFM) using low frequency bias voltage and heterodyne FM-KPFM using high frequency bias voltage were performed on the surface potential measurement. A silicon substrate patterned with p- and n-type impurities was used as a quantitative sample. The multi-pass scanning method in the measurements of FM-KPFM and heterodyne FM-KPFM was used to eliminate the effect of the tip–sample distance dependence. The measured surface potentials become lower in the order of the p-type region, n-type region and n+-type region by both FM-KPFM and heterodyne FM-KPFM, which are in good agreement with the order of the work functions of the pn-patterned Si sample. We observed the difference in the surface potentials due to the surface band bending measured by FM-KPFM and heterodyne FM-KPFM. The difference is due to the fact that the charge transfer between the surface and bulk levels may or may not respond to AC bias voltage.
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Affiliation(s)
- Ryo Izumi
- Department of Applied Physics, Graduate School of Engineering, Osaka University, 2-1 Yamadaoka, Suita, Osaka 565-0871, Japan
| | - Yan Jun Li
- Department of Applied Physics, Graduate School of Engineering, Osaka University, 2-1 Yamadaoka, Suita, Osaka 565-0871, Japan
| | - Yoshitaka Naitoh
- Department of Applied Physics, Graduate School of Engineering, Osaka University, 2-1 Yamadaoka, Suita, Osaka 565-0871, Japan
| | - Yasuhiro Sugawara
- Department of Applied Physics, Graduate School of Engineering, Osaka University, 2-1 Yamadaoka, Suita, Osaka 565-0871, Japan
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Abstract
Titanium dioxide (TiO2) is of considerable interest as a photocatalyst and a catalyst support. Surface hydroxyl groups (OH) are the most common adsorbates on the TiO2 surface and are believed to play crucial roles in their applications. Although the characteristics of bridging hydroxyl (OHbr) have been well understood, the adsorption structure and charged states of terminal hydroxyl (OHt) have not yet been experimentally elucidated at an atomic scale. In this study, we have investigated an isolated OHt on the rutile TiO2(110) surface by atomic force microscopy (AFM) and Kelvin probe force microscopy (KPFM). We found that OHt is in a negatively charged state. The unique characteristic of OHt is different from that of OHbr and involves the amphoterism and diversity of catalytic reactions of TiO2.
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Affiliation(s)
- Masato Miyazaki
- Department of Applied Physics, Graduate School of Engineering, Osaka University, 2-1 Yamadaoka, Suita, Osaka 565-0871, Japan
| | - Yasuhiro Sugawara
- Department of Applied Physics, Graduate School of Engineering, Osaka University, 2-1 Yamadaoka, Suita, Osaka 565-0871, Japan
| | - Yan Jun Li
- Department of Applied Physics, Graduate School of Engineering, Osaka University, 2-1 Yamadaoka, Suita, Osaka 565-0871, Japan
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Adachi Y, Sang H, Sugawara Y, Li YJ. Single hydrogen atom manipulation for reversible deprotonation of water on a rutile TiO(2) (110) surface. Commun Chem 2021; 4:5. [PMID: 36697495 DOI: 10.1038/s42004-020-00444-4] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2020] [Accepted: 12/07/2020] [Indexed: 01/28/2023] Open
Abstract
The discovery of hydrogen atoms on the TiO2 surface is crucial for many practical applications, including photocatalytic water splitting. Electronically activating interfacial hydrogen atoms on the TiO2 surface is a common way to control their reactivity. Modulating the potential landscape is another way, but dedicated studies for such an activation are limited. Here we show the single hydrogen atom manipulation, and on-surface facilitated water deprotonation process on a rutile TiO2 (110) surface using low temperature atomic force microscopy and Kelvin probe force spectroscopy. The configuration of the hydrogen atom is manipulated on this surface step by step using the local field. Furthermore, we quantify the force needed to relocate the hydrogen atom on this surface using force spectroscopy and density functional theory. Reliable control of hydrogen atoms provides a new mechanistic insight of the water molecules on a metal oxide surface.
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Wen HF, Sang H, Sugawara Y, Li YJ. Imaging oxygen molecular adsorption and dissociation on the Ti site of rutile TiO 2(110) surface with real configuration at 78 K by atomic force microscopy. Phys Chem Chem Phys 2020; 22:19795-19801. [PMID: 32844830 DOI: 10.1039/d0cp03549a] [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: 11/21/2022]
Abstract
Understanding oxygen adsorption and dissociation on the five-fold coordinated titanium (Ti5c) site of the rutile TiO2 surface is important in clarifying chemical reaction processes. Accordingly, three different configurations of molecularly adsorbed O2, including parallel side-on, inclined side-on and end-on configurations, and their dissociation were directly observed with atomic resolution at 78 K by atomic force microscopy. Our results experimentally demonstrated that the three adsorbed O2 configurations could be changed by electric field stimulation. The initial configurations of the adsorbed O2 and transition of O2 configurations were related to their coverage. On the other hand, the tunneling current stimulation could dissociate these O2 species, indicating that they are precursors for the O adatom (Oad). It is proposed that the effect of electric field stimulation contributes to the transition of these three adsorbed O2 configurations, and the effect of the tunneling current is the main factor for the dissociation of the adsorbed O2. In addition, based on the atomic contrast and height histograms of Oad, different charge states of Oad were observed, which could coexist on the surface region. The present study demonstrates an intuitional observation of O2 adsorption and dissociation on the Ti5c site, and thus is expected to be useful to understand the surface reactions on the oxide surface.
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Affiliation(s)
- Huan Fei Wen
- Key Laboratory of Instrumentation Science and Dynamic Measurement, School of Instrument and Electronics, North University of China, Taiyuan, Shanxi 030051, China and Department of Applied Physics, Graduate School of Engineering, Osaka University, 2-1 Yamadaoka, Suita, Osaka 5650871, Japan.
| | - Hongqian Sang
- Institute for Interdisciplinary Research, Jianghan University, Wuhan, 430056, China
| | - Yasuhiro Sugawara
- Key Laboratory of Instrumentation Science and Dynamic Measurement, School of Instrument and Electronics, North University of China, Taiyuan, Shanxi 030051, China and Department of Applied Physics, Graduate School of Engineering, Osaka University, 2-1 Yamadaoka, Suita, Osaka 5650871, Japan.
| | - Yan Jun Li
- Department of Applied Physics, Graduate School of Engineering, Osaka University, 2-1 Yamadaoka, Suita, Osaka 5650871, Japan.
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Adachi Y, Sugawara Y, Li YJ. Atomic Scale Three-Dimensional Au Nanocluster on a Rutile TiO 2 (110) Surface Resolved by Atomic Force Microscopy. J Phys Chem Lett 2020; 11:7153-7158. [PMID: 32787303 DOI: 10.1021/acs.jpclett.0c02042] [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: 06/11/2023]
Abstract
The atomic structure of a three-dimensional Au nanocluster on a TiO2 surface is important for various studies such as photocatalysis and chemical reactions on metal oxide surfaces. However, accessing the atomic structure of a metal nanocluster supported on a metal oxide surface is still challenging possibly because of its small size, complexity, and flexible structure. Here, we report a detuning imaging mode combined with an atomically sharp tip to address these challenges. Using this method, for the first time, we resolve a three-dimensional Au nanocluster on a rutile TiO2 (110) surface. We found that the Au nanocluster was continuously adsorbed at the upper and lower terraces. Our results open up a new methodology for studying subnanometer clusters at various surfaces at an atomic scale.
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Affiliation(s)
- Yuuki Adachi
- Department of Applied Physics, Osaka University, 2-1 Yamadaoka, Suita, Osaka 565-0871, Japan
| | - Yasuhiro Sugawara
- Department of Applied Physics, Osaka University, 2-1 Yamadaoka, Suita, Osaka 565-0871, Japan
| | - Yan Jun Li
- Department of Applied Physics, Osaka University, 2-1 Yamadaoka, Suita, Osaka 565-0871, Japan
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Wen HF, Sugawara Y, Li YJ. Multi-Channel Exploration of O Adatom on TiO 2(110) Surface by Scanning Probe Microscopy. Nanomaterials (Basel) 2020; 10:nano10081506. [PMID: 32751956 PMCID: PMC7466602 DOI: 10.3390/nano10081506] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/08/2020] [Revised: 07/22/2020] [Accepted: 07/29/2020] [Indexed: 01/28/2023]
Abstract
We studied the O2 dissociated state under the different O2 exposed temperatures with atomic resolution by scanning probe microscopy (SPM) and imaged the O adatom by simultaneous atomic force microscopy (AFM)/scanning tunneling microscopy (STM). The effect of AFM operation mode on O adatom contrast was investigated, and the interaction of O adatom and the subsurface defect was observed by AFM/STM. Multi-channel exploration was performed to investigate the charge transfer between the adsorbed O and the TiO2(110) by obtaining the frequency shift, tunneling current and local contact potential difference at an atomic scale. The tunneling current image showed the difference of the tunneling possibility on the single O adatom and paired O adatoms, and the local contact potential difference distribution of the O-TiO2(110) surface institutively revealed the charge transfer from TiO2(110) surface to O adatom. The experimental results are expected to be helpful in investigating surface/interface properties by SPM.
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Affiliation(s)
- Huan Fei Wen
- Key Laboratory of Instrumentation Science and Dynamic Measurement, School of Instrument and Electronics, North University of China, Taiyuan 030051, China; (H.F.W.); (Y.S.)
- Department of Applied Physics, Graduate School of Engineering, Osaka University, 2-1 Yamadaoka, Suita, Osaka 565-0871, Japan
| | - Yasuhiro Sugawara
- Key Laboratory of Instrumentation Science and Dynamic Measurement, School of Instrument and Electronics, North University of China, Taiyuan 030051, China; (H.F.W.); (Y.S.)
- Department of Applied Physics, Graduate School of Engineering, Osaka University, 2-1 Yamadaoka, Suita, Osaka 565-0871, Japan
| | - Yan Jun Li
- Department of Applied Physics, Graduate School of Engineering, Osaka University, 2-1 Yamadaoka, Suita, Osaka 565-0871, Japan
- Correspondence:
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12
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Sokolović I, Reticcioli M, Čalkovský M, Wagner M, Schmid M, Franchini C, Diebold U, Setvín M. Resolving the adsorption of molecular O 2 on the rutile TiO 2(110) surface by noncontact atomic force microscopy. Proc Natl Acad Sci U S A 2020; 117:14827-14837. [PMID: 32527857 PMCID: PMC7334520 DOI: 10.1073/pnas.1922452117] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Interaction of molecular oxygen with semiconducting oxide surfaces plays a key role in many technologies. The topic is difficult to approach both by experiment and in theory, mainly due to multiple stable charge states, adsorption configurations, and reaction channels of adsorbed oxygen species. Here we use a combination of noncontact atomic force microscopy (AFM) and density functional theory (DFT) to resolve [Formula: see text] adsorption on the rutile [Formula: see text](110) surface, which presents a longstanding challenge in the surface chemistry of metal oxides. We show that chemically inert AFM tips terminated by an oxygen adatom provide excellent resolution of both the adsorbed species and the oxygen sublattice of the substrate. Adsorbed [Formula: see text] molecules can accept either one or two electron polarons from the surface, forming superoxo or peroxo species. The peroxo state is energetically preferred under any conditions relevant for applications. The possibility of nonintrusive imaging allows us to explain behavior related to electron/hole injection from the tip, interaction with UV light, and the effect of thermal annealing.
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Affiliation(s)
- Igor Sokolović
- Institute of Applied Physics, Technische Universität Wien, 1040 Vienna, Austria
| | - Michele Reticcioli
- Institute of Applied Physics, Technische Universität Wien, 1040 Vienna, Austria
- Faculty of Physics, University of Vienna, 1090 Vienna, Austria
- Center for Computational Materials Science, University of Vienna, 1090 Vienna, Austria
| | - Martin Čalkovský
- Institute of Applied Physics, Technische Universität Wien, 1040 Vienna, Austria
- Institute of Physical Engineering, Brno University of Technology, 616 69 Brno, Czech Republic
| | - Margareta Wagner
- Institute of Applied Physics, Technische Universität Wien, 1040 Vienna, Austria
- Central European Institute of Technology, Brno University of Technology, 612 00 Brno, Czech Republic
| | - Michael Schmid
- Institute of Applied Physics, Technische Universität Wien, 1040 Vienna, Austria
| | - Cesare Franchini
- Faculty of Physics, University of Vienna, 1090 Vienna, Austria
- Center for Computational Materials Science, University of Vienna, 1090 Vienna, Austria
- Dipartimento di Fisica e Astronomia, Università di Bologna, 40127 Bologna, Italy
| | - Ulrike Diebold
- Institute of Applied Physics, Technische Universität Wien, 1040 Vienna, Austria
| | - Martin Setvín
- Institute of Applied Physics, Technische Universität Wien, 1040 Vienna, Austria;
- Department of Surface and Plasma Science, Faculty of Mathematics and Physics, Charles University, 180 00 Prague 8, Czech Republic
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13
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Adachi Y, Wen HF, Zhang Q, Miyazaki M, Sugawara Y, Li YJ. Elucidating the charge state of an Au nanocluster on the oxidized/reduced rutile TiO 2 (110) surface using non-contact atomic force microscopy and Kelvin probe force microscopy. Nanoscale Adv 2020; 2:2371-2375. [PMID: 36133366 PMCID: PMC9419554 DOI: 10.1039/c9na00776h] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/12/2019] [Accepted: 03/25/2020] [Indexed: 06/13/2023]
Abstract
The charge state of Au nanoclusters on oxidized/reduced rutile TiO2 (110) surfaces were investigated by a combination of non-contact atomic force microscopy and Kelvin probe force microscopy at 78 K under ultra-high vacuum. We found that the Au nanoclusters supported on oxidized/reduced surfaces had a relatively positive/negative charge state, respectively, compared with the substrate. In addition, the distance dependence of LCPD verified the contrast observed in the KPFM images. The physical background of charge transfer observation can be explained by the model of charge attachment/detachment from multiple oxygen vacancies/adatoms surrounding Au nanoclusters. These results suggest that the electronic properties of the Au nanoclusters are dramatically influenced by the condition of the support used.
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Affiliation(s)
- Yuuki Adachi
- Department of Applied Physics, Graduate School of Engineering, Osaka University 2-1 Yamadaoka Suita Osaka 565-0871 Japan
| | - Huan Fei Wen
- Key Laboratory of Instrumentation Science and Dynamic Measurement, School of Instrument and Electronics, North University of China Taiyuan Shanxi 030051 P. R. China
| | - Quanzhen Zhang
- Department of Applied Physics, Graduate School of Engineering, Osaka University 2-1 Yamadaoka Suita Osaka 565-0871 Japan
| | - Masato Miyazaki
- Department of Applied Physics, Graduate School of Engineering, Osaka University 2-1 Yamadaoka Suita Osaka 565-0871 Japan
| | - Yasuhiro Sugawara
- Department of Applied Physics, Graduate School of Engineering, Osaka University 2-1 Yamadaoka Suita Osaka 565-0871 Japan
| | - Yan Jun Li
- Department of Applied Physics, Graduate School of Engineering, Osaka University 2-1 Yamadaoka Suita Osaka 565-0871 Japan
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14
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Abstract
Chemical reactions catalyzed under heterogeneous conditions have recently expanded rapidly from traditional thermal catalysis to photocatalysis due to the rising concerns about sustainable development of energy and the environment. Adsorption of reactants on catalyst surfaces, subsequent surface reactions, and desorption of products from catalyst surfaces occur in both thermal catalysis and photocatalysis. TiO2 catalysts are widely used in thermal catalytic and photocatalytic reactions. Herein we review recent progress in surface chemistry, thermal catalysis and photocatalysis of TiO2 model catalysts from single crystals to nanocrystals with the aim of examining if the surface chemistry of TiO2 can bridge the fundamental understanding between thermal catalysis and photocatalysis. Following a brief introduction, the structures of major facets exposed on TiO2 catalysts, including surface reconstructions and defects, as well as the electronic structure and charge properties, are firstly summarized; then the recent progress in adsorption, thermal chemistry and photochemistry of small molecules on TiO2 single crystals and nanocrystals is comprehensively reviewed, focusing on manifesting the structure-(photo)activity relations and the commonalities/differences between thermal catalysis and photocatalysis; and finally concluding remarks and perspectives are given.
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Affiliation(s)
- Longxia Wu
- Hefei National Laboratory for Physical Sciences at the Microscale, Key Laboratory of Surface and Interface Chemistry and Energy Catalysis of Anhui Higher Education Institutes and Department of Chemical Physics, University of Science and Technology of China, Hefei 230026, P. R. China.
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