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Zhang B, Sun G, Ding S, Asakura H, Zhang J, Sautet P, Yan N. Atomically Dispersed Pt 1-Polyoxometalate Catalysts: How Does Metal-Support Interaction Affect Stability and Hydrogenation Activity? J Am Chem Soc 2019; 141:8185-8197. [PMID: 31030515 DOI: 10.1021/jacs.9b00486] [Citation(s) in RCA: 77] [Impact Index Per Article: 15.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Abstract
Unlike nanostructured metal catalysts, supported single-atom catalysts (SACs) contain only atomically dispersed metal atoms, hinting at much more pronounced metal-support effects. Herein, we take a series of polyoxometalate-supported Pt catalysts as examples to quantitatively investigate the stability of Pt atoms on oxide supports and how the Pt-support interaction influences the catalytic performance. For this entire series, we show that the Pt atoms prefer to stay at a 4-fold hollow site of one polyoxometalate molecule and that the least adsorption energy to obtain sintering-resistant Pt SACs is 5.50 eV, which exactly matches the cohesive energy of bulk Pt metal. Further, we compared their catalytic performance in several hydrogenation reactions and simulated the reaction pathways of propene hydrogenation by density functional theory (DFT) calculations. Both experimental and theoretical approaches suggest that despite the Pt1-support interactions being different, the reaction pathways of various Pt1-polyoxometalate catalysts are very similar and their effective reaction barriers are close to each other and as low as 24 kJ/mol, indicating the possibility of obtaining SACs with improved stability without compromising activity. DFT calculations show that all reaction elementary steps take place only on the Pt atom without involving neighboring O atoms and that hydrogenation proceeds from the molecularly adsorbed H2 species. Pt SACs give a weaker H2 adsorption energy than Pt clusters or surfaces, resulting in small adsorption equilibrium constants and small apparent activation barriers, which agree between experiment and theory.
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Affiliation(s)
- Bin Zhang
- Department of Chemical and Biomolecular Engineering , National University of Singapore , 4 Engineering Drive 4 , 117585 Singapore
| | - Geng Sun
- Department of Chemical and Biomolecular Engineering , University of California, Los Angeles , Los Angeles , California 90095 , United States
| | - Shipeng Ding
- Department of Chemical and Biomolecular Engineering , National University of Singapore , 4 Engineering Drive 4 , 117585 Singapore
| | - Hiroyuki Asakura
- Elements Strategy Initiative for Catalysts & Batteries (ESICB) , Kyoto University , Kyoto 615-8245 , Japan.,Department of Molecular Engineering, Graduate School of Engineering , Kyoto University , Kyotodaigaku Katsura, Nishikyo-ku, Kyoto 615-8510 , Japan
| | - Jia Zhang
- Institute of High Performance Computing , Agency for Science, Technology and Research , 1 Fusionopolis Way #16-16 Connexis , 138632 , Singapore
| | - Philippe Sautet
- Department of Chemical and Biomolecular Engineering , University of California, Los Angeles , Los Angeles , California 90095 , United States.,Department of Chemistry and Biochemistry , University of California, Los Angeles , Los Angeles , California 90095 , United States
| | - Ning Yan
- Department of Chemical and Biomolecular Engineering , National University of Singapore , 4 Engineering Drive 4 , 117585 Singapore
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Wang J, Zhang Y. Topologic connection between 2-D layered structures and 3-D diamond structures for conventional semiconductors. Sci Rep 2016; 6:24660. [PMID: 27090430 PMCID: PMC4835777 DOI: 10.1038/srep24660] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2016] [Accepted: 03/29/2016] [Indexed: 11/25/2022] Open
Abstract
When coming to identify new 2D materials, our intuition would suggest us to look from layered instead of 3D materials. However, since graphite can be hypothetically derived from diamond by stretching it along its [111] axis, many 3D materials can also potentially be explored as new candidates for 2D materials. Using a density functional theory, we perform a systematic study over the common Group IV, III–V, and II–VI semiconductors along different deformation paths to reveal new structures that are topologically connected to but distinctly different from the 3D parent structure. Specifically, we explore two major phase transition paths, originating respectively from wurtzite and NiAs structure, by applying compressive and tensile strain along the symmetry axis, and calculating the total energy changes to search for potential metastable states, as well as phonon spectra to examine the structural stability. Each path is found to further split into two branches under tensile strain–low buckled and high buckled structures, which respectively lead to a low and high buckled monolayer structure. Most promising new layered or planar structures identified include BeO, GaN, and ZnO on the tensile strain side, Ge, Si, and GaP on the compressive strain side.
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Affiliation(s)
- Jianwei Wang
- Department of Electrical and Computer Engineering, The University of North Carolina at Charlotte 9201 University City Boulevard, Charlotte, NC 28223, USA.,Microsystem and Terahertz Research Center, China Academy of Engineering Physics 596 Yinhe Road, Shuangliu, Sichuang, 610200, China
| | - Yong Zhang
- Department of Electrical and Computer Engineering, The University of North Carolina at Charlotte 9201 University City Boulevard, Charlotte, NC 28223, USA
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Hu W, Li Z, Yang J. Structural, electronic, and optical properties of hybrid silicene and graphene nanocomposite. J Chem Phys 2013; 139:154704. [DOI: 10.1063/1.4824887] [Citation(s) in RCA: 79] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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Kim M, Hwang J, Shields VB, Tiwari S, Spencer MG, Lee JW. SiC surface orientation and Si loss rate effects on epitaxial graphene. NANOSCALE RESEARCH LETTERS 2012; 7:186. [PMID: 22410299 PMCID: PMC3323459 DOI: 10.1186/1556-276x-7-186] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 10/29/2011] [Accepted: 03/12/2012] [Indexed: 05/31/2023]
Abstract
We have explored the properties of SiC-based epitaxial graphene grown in a cold wall UHV chamber. The effects of the SiC surface orientation and silicon loss rate were investigated by comparing the characteristics of each formed graphene. Graphene was grown by thermal decomposition on both the silicon (0001) and carbon (000-1) faces of on-axis semi-insulating 6H-SiC with a "face-down" and "face-up" orientations. The thermal gradient, in relation to the silicon flux from the surface, was towards the surface and away from the surface, respectively, in the two configurations. Raman results indicate the disorder characteristics represented by ID/IG down to < 0.02 in Si-face samples and < 0.05 in C-faces over the 1 cm2 wafer surface grown at 1,450°C. AFM examination shows a better morphology in face-down surfaces. This study suggests that the optimum configuration slows the thermal decomposition and allows the graphene to form near the equilibrium. The Si-face-down orientation (in opposition to the temperature gradient) results in a better combination of low disorder ratio, ID/IG, and smooth surface morphology. Mobility of Si-face-down orientation has been measured as high as approximately 1,500 cm2/Vs at room temperature. Additionally, the field effect transistors have been fabricated on both Si-face-down and C-face-down showing an ambipolar behavior with more favorable electron conduction.
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Affiliation(s)
- Moonkyung Kim
- School of Electrical and Computer Engineering, Cornell University, 410 Thurston Avenue, Ithaca, NY 14850-2488, USA
| | - Jeonghyun Hwang
- School of Electrical and Computer Engineering, Cornell University, 410 Thurston Avenue, Ithaca, NY 14850-2488, USA
| | - Virgil B Shields
- School of Electrical and Computer Engineering, Cornell University, 410 Thurston Avenue, Ithaca, NY 14850-2488, USA
| | - Sandip Tiwari
- School of Electrical and Computer Engineering, Cornell University, 410 Thurston Avenue, Ithaca, NY 14850-2488, USA
| | - Michael G Spencer
- School of Electrical and Computer Engineering, Cornell University, 410 Thurston Avenue, Ithaca, NY 14850-2488, USA
| | - Jo-Won Lee
- Department of Convergence Nanoscience, Hanyang University, 17 Haengdang-dong, Seongdong-gu, Seoul, 133-791, South Korea
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Ding Y, Wang Y, Ni J, Shi L, Shi S, Li C, Tang W. First-principles study of half-metallicity in semi-hydrogenated BC3, BC5, BC7, and B-doped graphone sheets. NANOSCALE RESEARCH LETTERS 2011; 6:190. [PMID: 21711690 PMCID: PMC3211247 DOI: 10.1186/1556-276x-6-190] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 10/21/2010] [Accepted: 03/01/2011] [Indexed: 05/31/2023]
Abstract
Using first principles calculations, we investigate the electronic structures of semi-hydrogenated BC3, BC5, BC7, and B-doped graphone sheets. We find that all the semi-hydrogenated boron-carbon sheets exhibit half-metallic behaviors. The magnetism originates from the non-bonding pz orbitals of carbon atoms, which cause the flat bands to satisfy the Stoner criterion. On the other hand, boron atoms weaken the magnetic moments of nearby carbon atoms and act as holes doped in the sheets. It induces the down shift of the Fermi level and the half-metallicity in semi-hydrogenated sheets. Our studies demonstrate that the semi-hydrogenation is an effective route to achieve half-metallicity in the boron-carbon systems.
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Affiliation(s)
- Yi Ding
- Department of Physics, Hangzhou Normal University, Hangzhou, Zhejiang 310036, People's Republic of China
| | - Yanli Wang
- Department of Physics, Center for Optoelectronics Materials and Devices, Zhejiang Sci-Tech University, Xiasha College Park, Hangzhou, Zhejiang 310018, People's Republic of China
| | - Jun Ni
- Department of Physics, Key Laboratory of Atomic and Molecular Nanoscience (Ministry of Education), Tsinghua University, Beijing 100084, People's Republic of China
| | - Lin Shi
- Suzhou Institute of Nano-Tech and Nano-Bionics, Chinese Academy of Sciences, Suzhou 215125, People's Republic of China
| | - Siqi Shi
- Department of Physics, Center for Optoelectronics Materials and Devices, Zhejiang Sci-Tech University, Xiasha College Park, Hangzhou, Zhejiang 310018, People's Republic of China
| | - Chaorong Li
- Department of Physics, Center for Optoelectronics Materials and Devices, Zhejiang Sci-Tech University, Xiasha College Park, Hangzhou, Zhejiang 310018, People's Republic of China
| | - Weihua Tang
- Department of Physics, Center for Optoelectronics Materials and Devices, Zhejiang Sci-Tech University, Xiasha College Park, Hangzhou, Zhejiang 310018, People's Republic of China
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Tsu R. Superlattices: problems and new opportunities, nanosolids. NANOSCALE RESEARCH LETTERS 2011; 6:127. [PMID: 21711653 PMCID: PMC3211173 DOI: 10.1186/1556-276x-6-127] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 08/11/2010] [Accepted: 02/10/2011] [Indexed: 05/31/2023]
Abstract
Superlattices were introduced 40 years ago as man-made solids to enrich the class of materials for electronic and optoelectronic applications. The field metamorphosed to quantum wells and quantum dots, with ever decreasing dimensions dictated by the technological advancements in nanometer regime. In recent years, the field has gone beyond semiconductors to metals and organic solids. Superlattice is simply a way of forming a uniform continuum for whatever purpose at hand. There are problems with doping, defect-induced random switching, and I/O involving quantum dots. However, new opportunities in component-based nanostructures may lead the field of endeavor to new heights. The all important translational symmetry of solids is relaxed and local symmetry is needed in nanosolids.
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Affiliation(s)
- Raphael Tsu
- University of North Carolina at Charlotte, Charlotte, NC 28223 USA.
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