We calculate the configurations, electronic structures, vibrational properties at the coronene/Ru（0001） interface, and adsorption of a single Pt atom on coronene/Ru（0001） based on density functional theory calcula...We calculate the configurations, electronic structures, vibrational properties at the coronene/Ru（0001） interface, and adsorption of a single Pt atom on coronene/Ru（0001） based on density functional theory calculations. The geometric structures and electronic structures of the coronene on Ru（0001） are compared with those of the graphene/Ru（0001）. The results show that the coronene/Ru（0001） can be a simplified model system used to describe the interaction between graphene and ruthenium. Further calculations of the vibrational properties of coronene molecule adsorbed on Ru（0001） suggest that the phonon properties of differently corrugated regions of graphene on Ru（0001） are different. This model system is also used to investigate the selective adsorption of Ft atoms on graphene/Ru（0001）. The configurations of Pt on coronene/Ru（0001） with the lowest binding energy give clues to explain the experimental observation that a Pt cluster selectively adsorbs on the second highest regions of graphene/Ru（0001）. This work provides a simple model for understanding the adsorption properties and vibrational properties of graphene on Ru（0001） substrate.展开更多
We report on the formation of a graphene monolayer on a Ru（0001） surface by annealing the Ru（0001） crystal. The samples are characterized by scanning tunnelling microscopy （STM） and Auger electron spectroscopy ...We report on the formation of a graphene monolayer on a Ru（0001） surface by annealing the Ru（0001） crystal. The samples are characterized by scanning tunnelling microscopy （STM） and Auger electron spectroscopy （AES）. STM images show that the Moire pattern is caused by the graphene layer mismatched with the underlying Ru（0001） surface and has an N × N superlattice. It is further found that the graphene monolayer on a Ru（0001） surface is very stable at high temperatures. Our results provide a simple and convenient method to produce a graphene monolayer on the Ru（0001） surface, which is used as a template for fabricating functional nanostructures needed in future nano devices and catalysis.展开更多
Periodic density functional theory（DFT） calculations are presented to describe the adsorption and decomposition of CH3OH on Ru（0001） surfaces with different coverages, including p（3 ×2）, p（2×2）, and ...Periodic density functional theory（DFT） calculations are presented to describe the adsorption and decomposition of CH3OH on Ru（0001） surfaces with different coverages, including p（3 ×2）, p（2×2）, and p（2× 1） unit cells, corresponding to monolayer（ML） coverages of 1/6, 1/4, and 1/2, respectively. The geometries and energies of all species involved in methanol dissociation were analyzed, and the initial decomposition reactions of methanol and the subsequent dehydrogenations reactions of CH3O and CH2OH were all computed at 1/2, 1/4, and 1/6 ML coverage on the Ru（0001） surface. The results show that coverage exerts some effects on the stable adsorption of CH30, CH2OH, and CH3, that is, the lower the coverage, the stronger the adsorption. Coverage also exerts effects on the initial decomposition of methanol. C-H bond breakage is favored at 1/2 ML, whereas C-H and O--H bond cleavages are preferred at 1/4 and 1/6 ML on the Ru（0001） surface, respectively. At 1/4 ML coverage on the Ru（0001） surface, the overall reaction mechanism can be written as 9CH3OH ,3CH30＋6CH2OH＋9H ,6CH20＋3CHOH＋18H , 7CHO＋COH＋CH＋OH＋26H → 8CO＋C＋O＋36H.展开更多
High quality sub-monolayer, monolayer, and bilayer graphene were grown on Ru（0001）. For the sub-monolayer graphene, the size of graphene islands with zigzag edges can be controlled by the dose of ethylene exposure. ...High quality sub-monolayer, monolayer, and bilayer graphene were grown on Ru（0001）. For the sub-monolayer graphene, the size of graphene islands with zigzag edges can be controlled by the dose of ethylene exposure. By increasing the dose of ethylene to 100 Langmuir at a high substrate temperature （800 ℃）, high quality single-crystalline monolayer graphene was synthesized on Ru（0001）. High quality bilayer graphene was formed by further increasing the dose of ethylene while reducing the cooling rate to 5 ℃/min. Raman spectroscopy revealed the vibrational states of graphene, G and 2D peaks appeared only in the bilayer graphene, which demonstrates that it behaves as the intrinsic graphene. Our present work affords methods to produce high quality sub-monolayer, monolayer, and bilayer graphene, both for basic research and applications.展开更多
Electrosorption of oxygen and CO on Ru(0001) surface were investigated by ex-situ electron diffraction (LEED/RHEED), AES and electrochemical data. The Ru(0001) surface exhibited a strongly affinity for oxygen which g...Electrosorption of oxygen and CO on Ru(0001) surface were investigated by ex-situ electron diffraction (LEED/RHEED), AES and electrochemical data. The Ru(0001) surface exhibited a strongly affinity for oxygen which gave preference to form a (22)-O phase. However, anodization of Ru(0001) electrode produced a (11)-O phase. A coadsorption structure (2CO+O)(22) / Ru(0001) was performed from electrosorption of CO on Ru(0001) surface in electrolyte solution.展开更多
The electrooxidation of CO on Ru (0001) and RuO2 (100) electrode surfaces were characterized by cyclic voltammetry, AES and RHEED. The CO adlayer was first partially oxidized at 0.8 V, which is controlled by the atta...The electrooxidation of CO on Ru (0001) and RuO2 (100) electrode surfaces were characterized by cyclic voltammetry, AES and RHEED. The CO adlayer was first partially oxidized at 0.8 V, which is controlled by the attack of oxygen species toward the Ru(0001) surface. The remaining CO adlayer oxidation at 0.55 V is related to the combination of CO molecules with oxygen species already located on the surface. In contrast, successive peaks on RuO2(100) at 0.4 V and 0.72 V are observed, which shows that CO molecules can directly react with two different lattice-oxygen on the surface to carbon dioxide.展开更多
Monolayer graphene was epitaxially grown on Ru(0001) through exposure of the Ru(0001) to ethylene at room temperature followed by annealing in ultrahigh vacuum at elevated temperatures. The resulting graphene structur...Monolayer graphene was epitaxially grown on Ru(0001) through exposure of the Ru(0001) to ethylene at room temperature followed by annealing in ultrahigh vacuum at elevated temperatures. The resulting graphene structures were studied by scanning tunneling microscopy (STM), X-ray photoelectron spectroscopy (XPS), and ultraviolet photoelectron spectroscopy (UPS). The graphene/Ru(0001) surface was used as a periodic template for growth of metal nanoclusters. Highly dispersed Pt clusters with well controlled size and spatial distribution were fabricated on the surface.展开更多
We report on temperature-programmed growth of graphene islands on Ru （0001） at annealing temperatures of 700 ℃, 800 ℃, and 900 ℃. The sizes of the islands each show a nonlinear increase with the annealing tempera...We report on temperature-programmed growth of graphene islands on Ru （0001） at annealing temperatures of 700 ℃, 800 ℃, and 900 ℃. The sizes of the islands each show a nonlinear increase with the annealing temperature. In 700 ℃ and 800 ℃annealings, the islands have nearly the same sizes and their ascending edges are embedded in the upper steps of the ruthenium substrate, which is in accordance with the etching growth mode. In 900 ℃ annealing, the islands are much larger and of lower quality, which represents the early stage of Smoluchowski ripening. A longer time annealing at 900 ℃ brings the islands to final equilibrium with an ordered moire pattern. Our work provides new details about graphene early growth stages that could facilitate the better control of such a growth to obtain graphene with ideal size and high quality.展开更多
基金Project supported by the National Natural Science Foundation of China （Grant No. 10874219）, the National Basic Research Program of China （Grant Nos. 2011CB921702 and 2011CB808401）, and the Shanghai Supercomputing Center, China.
文摘We calculate the configurations, electronic structures, vibrational properties at the coronene/Ru（0001） interface, and adsorption of a single Pt atom on coronene/Ru（0001） based on density functional theory calculations. The geometric structures and electronic structures of the coronene on Ru（0001） are compared with those of the graphene/Ru（0001）. The results show that the coronene/Ru（0001） can be a simplified model system used to describe the interaction between graphene and ruthenium. Further calculations of the vibrational properties of coronene molecule adsorbed on Ru（0001） suggest that the phonon properties of differently corrugated regions of graphene on Ru（0001） are different. This model system is also used to investigate the selective adsorption of Ft atoms on graphene/Ru（0001）. The configurations of Pt on coronene/Ru（0001） with the lowest binding energy give clues to explain the experimental observation that a Pt cluster selectively adsorbs on the second highest regions of graphene/Ru（0001）. This work provides a simple model for understanding the adsorption properties and vibrational properties of graphene on Ru（0001） substrate.
基金Project supported by the National Natural Science Foundation of China （Grant Nos 90406022 and 10674159）.
文摘We report on the formation of a graphene monolayer on a Ru（0001） surface by annealing the Ru（0001） crystal. The samples are characterized by scanning tunnelling microscopy （STM） and Auger electron spectroscopy （AES）. STM images show that the Moire pattern is caused by the graphene layer mismatched with the underlying Ru（0001） surface and has an N × N superlattice. It is further found that the graphene monolayer on a Ru（0001） surface is very stable at high temperatures. Our results provide a simple and convenient method to produce a graphene monolayer on the Ru（0001） surface, which is used as a template for fabricating functional nanostructures needed in future nano devices and catalysis.
基金Supported by the Key Program of Natural Science of Tianjin, China（No. 13JCZDJC26800）, the National Natural Science Foundation of China（Nos.21503122, 21346002）, the Shanxi Province Science Foundation for Youths, China（No.2014021016-2）, the Scientific and Technological Programs in Shanxi Province, China（No.2015031017） and the Foundation of Key Laboratory of Advanced Energy Materials Chemistry of Ministry of Education of China.
文摘Periodic density functional theory（DFT） calculations are presented to describe the adsorption and decomposition of CH3OH on Ru（0001） surfaces with different coverages, including p（3 ×2）, p（2×2）, and p（2× 1） unit cells, corresponding to monolayer（ML） coverages of 1/6, 1/4, and 1/2, respectively. The geometries and energies of all species involved in methanol dissociation were analyzed, and the initial decomposition reactions of methanol and the subsequent dehydrogenations reactions of CH3O and CH2OH were all computed at 1/2, 1/4, and 1/6 ML coverage on the Ru（0001） surface. The results show that coverage exerts some effects on the stable adsorption of CH30, CH2OH, and CH3, that is, the lower the coverage, the stronger the adsorption. Coverage also exerts effects on the initial decomposition of methanol. C-H bond breakage is favored at 1/2 ML, whereas C-H and O--H bond cleavages are preferred at 1/4 and 1/6 ML on the Ru（0001） surface, respectively. At 1/4 ML coverage on the Ru（0001） surface, the overall reaction mechanism can be written as 9CH3OH ,3CH30＋6CH2OH＋9H ,6CH20＋3CHOH＋18H , 7CHO＋COH＋CH＋OH＋26H → 8CO＋C＋O＋36H.
基金supported by the National Basic Research Program of China(Grant Nos.2013CBA01600 and 2011CB932700)the National Natural Science Foundation of China(Grant Nos.61222112 and 11334006)
文摘High quality sub-monolayer, monolayer, and bilayer graphene were grown on Ru（0001）. For the sub-monolayer graphene, the size of graphene islands with zigzag edges can be controlled by the dose of ethylene exposure. By increasing the dose of ethylene to 100 Langmuir at a high substrate temperature （800 ℃）, high quality single-crystalline monolayer graphene was synthesized on Ru（0001）. High quality bilayer graphene was formed by further increasing the dose of ethylene while reducing the cooling rate to 5 ℃/min. Raman spectroscopy revealed the vibrational states of graphene, G and 2D peaks appeared only in the bilayer graphene, which demonstrates that it behaves as the intrinsic graphene. Our present work affords methods to produce high quality sub-monolayer, monolayer, and bilayer graphene, both for basic research and applications.
基金This work was financially supported by the Ministry of Science and Technology （MOST Nos. 2011CB921702 and 2011CB932700）, National Natural Science Foundation of China （NSFC No. 61222112）, Multilevel Molecular Assemblies： Structure, Dynamics, and Functions （TRR61）, Shanghai Supercomputer Center （SSC）, and Chinese Academy of Sciences （CAS） in China. WAH acknowledges support from the UK Car-Parinello consortium, grant No. EP/F037783/1.
基金W.B.Wang is grateful for a fellowship from the Max-Planck-Gesellschaft(MPG). We also thank Prof. G. Ertl for helpful suggestions and discussions.
文摘Electrosorption of oxygen and CO on Ru(0001) surface were investigated by ex-situ electron diffraction (LEED/RHEED), AES and electrochemical data. The Ru(0001) surface exhibited a strongly affinity for oxygen which gave preference to form a (22)-O phase. However, anodization of Ru(0001) electrode produced a (11)-O phase. A coadsorption structure (2CO+O)(22) / Ru(0001) was performed from electrosorption of CO on Ru(0001) surface in electrolyte solution.
文摘The electrooxidation of CO on Ru (0001) and RuO2 (100) electrode surfaces were characterized by cyclic voltammetry, AES and RHEED. The CO adlayer was first partially oxidized at 0.8 V, which is controlled by the attack of oxygen species toward the Ru(0001) surface. The remaining CO adlayer oxidation at 0.55 V is related to the combination of CO molecules with oxygen species already located on the surface. In contrast, successive peaks on RuO2(100) at 0.4 V and 0.72 V are observed, which shows that CO molecules can directly react with two different lattice-oxygen on the surface to carbon dioxide.
基金Supported by the National Natural Science Foundation of China (Grant Nos. 20603037, 20733008 and 20873143)Major State Basic Research Development Program of China (Grant No: 2007CB815205)One Hundred Talents Project of Chinese Academy of Sciences
文摘Monolayer graphene was epitaxially grown on Ru(0001) through exposure of the Ru(0001) to ethylene at room temperature followed by annealing in ultrahigh vacuum at elevated temperatures. The resulting graphene structures were studied by scanning tunneling microscopy (STM), X-ray photoelectron spectroscopy (XPS), and ultraviolet photoelectron spectroscopy (UPS). The graphene/Ru(0001) surface was used as a periodic template for growth of metal nanoclusters. Highly dispersed Pt clusters with well controlled size and spatial distribution were fabricated on the surface.
基金Project supported by the National Basic Research Program of China (Grant Nos. 2011CB932700,2010CB923004,2010CB923004,and 2009CB929103)the National Natural Science Foundation of China (Grant Nos. 10834011 and 60976089)the Main Direction Program of Knowledge Innovation of the Chinese Academy of Sciences (Grant No. KJCX2-YW-W22)
文摘We report on temperature-programmed growth of graphene islands on Ru （0001） at annealing temperatures of 700 ℃, 800 ℃, and 900 ℃. The sizes of the islands each show a nonlinear increase with the annealing temperature. In 700 ℃ and 800 ℃annealings, the islands have nearly the same sizes and their ascending edges are embedded in the upper steps of the ruthenium substrate, which is in accordance with the etching growth mode. In 900 ℃ annealing, the islands are much larger and of lower quality, which represents the early stage of Smoluchowski ripening. A longer time annealing at 900 ℃ brings the islands to final equilibrium with an ordered moire pattern. Our work provides new details about graphene early growth stages that could facilitate the better control of such a growth to obtain graphene with ideal size and high quality.
