Yitao Cui - Academia.edu (original) (raw)

Papers by Yitao Cui

The electronic structures of the Heusler type compounds Fe 3-x V x Si in the concentration range ... more The electronic structures of the Heusler type compounds Fe 3-x V x Si in the concentration range between x = 0 and x = 1 have been probed by photoemission spectroscopy (PES). The observed shift of Si 2p corelevel and the main valence band structres indicate a chemical potential shift to higher energy with increasing x. It is also clarified that the density of state at Fermi edge is owing to the collaboration of V 3d and Fe 3d derived states. Besides the decrease of the spectral intensity near Fermi edge with increasing x suggests the formation of pseudo gap at large x.

Nature Chemistry, 2011

Platinum-based heterogeneous catalysts are critical to many important commercial chemical process... more Platinum-based heterogeneous catalysts are critical to many important commercial chemical processes, but their efficiency is extremely low on a per metal atom basis, because only the surface active-site atoms are used. Catalysts with single-atom dispersions are thus highly desirable to maximize atom efficiency, but making them is challenging. Here we report the synthesis of a single-atom catalyst that consists of only isolated single Pt atoms anchored to the surfaces of iron oxide nanocrystallites. This single-atom catalyst has extremely high atom efficiency and shows excellent stability and high activity for both CO oxidation and preferential oxidation of CO in H2. Density functional theory calculations show that the high catalytic activity correlates with the partially vacant 5d orbitals of the positively charged, high-valent Pt atoms, which help to reduce both the CO adsorption energy and the activation barriers for CO oxidation.

International Journal of Pediatric Otorhinolaryngology, 2004

NixZn1−xFe2O4 (0.2≤x≤0.7) thin films with various compositions are prepared by alternative sputte... more NixZn1−xFe2O4 (0.2≤x≤0.7) thin films with various compositions are prepared by alternative sputtering technology from the two targets with the composition NiFe2O4 and ZnFe2O4. The films are deposited on (1 1 1) Si substrates directly and buffered with ZnFe2O4 underlayer, respectively, at room temperature and then annealed in air at 850 °C. For unbuffered films with the increasing of Zn content, the saturation magnetization Ms increases firstly and then decreases when x=0.40 the Ms reaches the maximum value about 400 emu/cc, while the coercivity Hc decreases monotonously. The films grown on substrates with ZnFe2O4 underlayer exhibit better magnetic properties than those deposited on directly Si substrates which indicates the importance of lattice match and structural similarity between the film and the underlayer.

Applied Surface Science, 2008

The interaction of cobalt atoms with silicon (1 1 1) surface has been investigated by means of sc... more The interaction of cobalt atoms with silicon (1 1 1) surface has been investigated by means of scanning tunneling microscopy (STM) and low-energy electron diffraction (LEED). Besides the Co silicide islands, we have successfully distinguished two inequivalent Co-induced 13×13 reconstructions on Si(1 1 1) surface. Our high-resolution STM images provide some structural properties of the two different 13×13 derived phases. Both of the two phases seem to form islands with single domain. The new findings will help us to understand the early stage of Co silicide formations.

Applied Physics Express, 2008

The half-Heusler compounds NiXSn (X = Ti, Zr, Hf) are regarded as examples of materials possessin... more The half-Heusler compounds NiXSn (X = Ti, Zr, Hf) are regarded as examples of materials possessing excellent thermoelectric properties. We have studied their electronic structures by photoemission spectroscopy excited by soft and hard X-ray synchrotron radiation. Although the overall features of the experimental valence band spectra are well explained by a calculated density of states,''in-gap'' states close to the Fermi energy emerge due to atomic disorder. These electronic states were further confirmed by core-level photoemission and appear to be key for excellent thermoelectric behavior. #

The interaction of cobalt atoms with silicon (111) surface has been investigated by means of scan... more The interaction of cobalt atoms with silicon (111) surface has been investigated by means of scanning tunneling microscopy (STM) and low-energy electron diffraction (LEED). Besides the Co silicide islands, we have successfully distinguished two inequivalent Co-induced √ 13 × √ 13 reconstructions on Si (111) surface. Our high-resolution STM images provide some structural properties of the two different √ 13 × √ 13 derived phases. Both of the two phases seem to form islands with single domain. The new findings will help us to understand the early stage of Co silicide formations.

The electronic structures of the Heusler type compounds Fe 3-x V x Si in the concentration range ... more The electronic structures of the Heusler type compounds Fe 3-x V x Si in the concentration range between x = 0 and x = 1 have been probed by photoemission spectroscopy (PES). The observed shift of Si 2p corelevel and the main valence band structres indicate a chemical potential shift to higher energy with increasing x. It is also clarified that the density of state at Fermi edge is owing to the collaboration of V 3d and Fe 3d derived states. Besides the decrease of the spectral intensity near Fermi edge with increasing x suggests the formation of pseudo gap at large x.

Nature Chemistry, 2011

Platinum-based heterogeneous catalysts are critical to many important commercial chemical process... more Platinum-based heterogeneous catalysts are critical to many important commercial chemical processes, but their efficiency is extremely low on a per metal atom basis, because only the surface active-site atoms are used. Catalysts with single-atom dispersions are thus highly desirable to maximize atom efficiency, but making them is challenging. Here we report the synthesis of a single-atom catalyst that consists of only isolated single Pt atoms anchored to the surfaces of iron oxide nanocrystallites. This single-atom catalyst has extremely high atom efficiency and shows excellent stability and high activity for both CO oxidation and preferential oxidation of CO in H2. Density functional theory calculations show that the high catalytic activity correlates with the partially vacant 5d orbitals of the positively charged, high-valent Pt atoms, which help to reduce both the CO adsorption energy and the activation barriers for CO oxidation.

International Journal of Pediatric Otorhinolaryngology, 2004

NixZn1−xFe2O4 (0.2≤x≤0.7) thin films with various compositions are prepared by alternative sputte... more NixZn1−xFe2O4 (0.2≤x≤0.7) thin films with various compositions are prepared by alternative sputtering technology from the two targets with the composition NiFe2O4 and ZnFe2O4. The films are deposited on (1 1 1) Si substrates directly and buffered with ZnFe2O4 underlayer, respectively, at room temperature and then annealed in air at 850 °C. For unbuffered films with the increasing of Zn content, the saturation magnetization Ms increases firstly and then decreases when x=0.40 the Ms reaches the maximum value about 400 emu/cc, while the coercivity Hc decreases monotonously. The films grown on substrates with ZnFe2O4 underlayer exhibit better magnetic properties than those deposited on directly Si substrates which indicates the importance of lattice match and structural similarity between the film and the underlayer.

Applied Surface Science, 2008

The interaction of cobalt atoms with silicon (1 1 1) surface has been investigated by means of sc... more The interaction of cobalt atoms with silicon (1 1 1) surface has been investigated by means of scanning tunneling microscopy (STM) and low-energy electron diffraction (LEED). Besides the Co silicide islands, we have successfully distinguished two inequivalent Co-induced 13×13 reconstructions on Si(1 1 1) surface. Our high-resolution STM images provide some structural properties of the two different 13×13 derived phases. Both of the two phases seem to form islands with single domain. The new findings will help us to understand the early stage of Co silicide formations.

Applied Physics Express, 2008

The half-Heusler compounds NiXSn (X = Ti, Zr, Hf) are regarded as examples of materials possessin... more The half-Heusler compounds NiXSn (X = Ti, Zr, Hf) are regarded as examples of materials possessing excellent thermoelectric properties. We have studied their electronic structures by photoemission spectroscopy excited by soft and hard X-ray synchrotron radiation. Although the overall features of the experimental valence band spectra are well explained by a calculated density of states,''in-gap'' states close to the Fermi energy emerge due to atomic disorder. These electronic states were further confirmed by core-level photoemission and appear to be key for excellent thermoelectric behavior. #

The interaction of cobalt atoms with silicon (111) surface has been investigated by means of scan... more The interaction of cobalt atoms with silicon (111) surface has been investigated by means of scanning tunneling microscopy (STM) and low-energy electron diffraction (LEED). Besides the Co silicide islands, we have successfully distinguished two inequivalent Co-induced √ 13 × √ 13 reconstructions on Si (111) surface. Our high-resolution STM images provide some structural properties of the two different √ 13 × √ 13 derived phases. Both of the two phases seem to form islands with single domain. The new findings will help us to understand the early stage of Co silicide formations.