Formation of TiO<sub>2</sub> Nanoparticles by Reactive-Layer-Assisted Deposition and Characterization by XPS and STM

Song, Zhen; Hrbek, Jan; Osgood, R. M.

doi:10.1021/nl0505703

Cited by 265 publications

(210 citation statements)

References 24 publications

Supporting

Mentioning

185

Contrasting

Order By: Relevance

“…The fitting and analysis of the spectra were performed as described in previous works. [5,30,31] While the signals that are marked as C-Ti-T x 2p 3/2 and C-Ti-T x 2p 1/2 [30] and correspond to Ti interactions with carbons and terminal atoms in Ti 3 C 2 T x look similar in both spectra, there is a visible increase in the signal intensities at ≈459 and ≈465 eV (these peaks are marked as TiO 2 2p 3/2 and TiO 2 2p 1/2 , respectively), [31] which is another indication of oxidation of MXenes produced via Route 1.…”

Section: Resultsmentioning

confidence: 99%

Effect of Synthesis on Quality, Electronic Properties and Environmental Stability of Individual Monolayer Ti₃C₂ MXene Flakes

Lipatov

Alhabeb

Lukatskaya

et al. 2016

Adv Elect Materials

1,397

1,032

View full text Add to dashboard Cite

Abstract2D transition metal carbide Ti 3 C 2 T x (T stands for surface termination), the most widely studied MXene, has shown outstanding electrochemical properties and promise for a number of bulk applications. However, electronic properties of individual MXene flakes, which are important for understanding the potential of these materials, remain largely unexplored. Herein, a modified synthetic method is reported for producing high-quality monolayer Ti 3 C 2 T x flakes. Field-effect transistors (FETs) based on monolayer Ti 3 C 2 T x flakes are fabricated and their electronic properties are measured. Individual Ti 3 C 2 T x flakes exhibit a high conductivity of 4600 ± 1100 S cm −1 and fieldeffect electron mobility of 2.6 ± 0.7 cm 2 V −1 s −1 . The resistivity of multilayer Ti 3 C 2 T x films is only one order of magnitude higher than the resistivity of individual flakes, which indicates a surprisingly good electron transport through the surface terminations of different flakes, unlike in many other 2D materials. Finally, the fabricated FETs are used to investigate the environmental stability and kinetics of oxidation of Ti 3 C 2 T x flakes in humid air. The high-quality Ti 3 C 2 T x flakes are reasonably stable and remain highly conductive even after their exposure to air for more than 24 h. It is demonstrated that after the initial exponential decay the conductivity of Ti 3 C 2 T x flakes linearly decreases with time, which is consistent with their edge oxidation. A l h a b e b , e t a l . i n A d v a n c e d E l e c t r o n i c M a t e r i a l s 2 ( 2 0 1 6 digitalcommons.unl.edu L i p a t o v &

show abstract

Section: Resultsmentioning

confidence: 99%

Effect of Synthesis on Quality, Electronic Properties and Environmental Stability of Individual Monolayer Ti₃C₂ MXene Flakes

Lipatov

Alhabeb

Lukatskaya

et al. 2016

Adv Elect Materials

1,397

1,032

View full text Add to dashboard Cite

show abstract

“…XPS of pristine nanotubes shows trace oxygen present at less than 1 at%. After the first step of titanium evaporation (sample 1), the Ti 2p 3/2 peak has a binding energy of ~459.0 eV (see Figure 3b), which is characteristic of Ti 4+ present in TiO 2 15,16 . This suggests that titanium atoms first react with any available oxygen to form completely oxidized titanium.…”

Section: Resultsmentioning

confidence: 99%

The Role of Oxygen at the Interface between Titanium and Carbon Nanotubes

Felten

Suarez-Martinez

et al. 2009

ChemPhysChem

View full text Add to dashboard Cite

[b] ((Dedication, optional)) We study the interface between carbon nanotubes (CNTs) IntroductionCarbon nanotubes appear as a good candidate to replace stateof-the-art inlaid copper interconnects in microprocessors. A key step for integration of CNTs in actual devices is the formation of stable and low-resistance ohmic contacts. Experimental results and calculations seem to agree that Ti and Pd are the best candidates for contacts in carbon nanotube based devices [1][2][3][4][5][6][7][8] . They are superior to conventional metals previously used in electronics such as Au, Al, and Pt which have associated high resistance Schottky barriers. Theoretical studies of pure metals on graphite suggest Ti as the best metal for contacts followed by Pd 5 , yet while low resistance Ohmic contacts have been experimentally reported in the case of Ti [1][2][3] , experimental results give Pd as the best choice due to better reliability and reproducibility 2,6 . One of the reasons invoked for this discrepancy is the high chemical reactivity of Ti compared to the other metals 2,6,9 : in realistic systems titanium oxidation occurs. But until now, no chemical study of the Ti/nanotube interface has been carried out in order to understand the phenomenon, nor supporting theoretical calculations.In this paper, we investigate the growth, electronic structure and chemical composition of Ti atoms on multiwall carbon nanotubes (MWNTs) by transmission electron microscopy (TEM), core levels photoemission spectroscopy (XPS) and density functional calculations. Results and DiscussionEvaporation of Ti on pristine MWCNTs leads to continuous amorphous coverage of the nanotube surface, even for small amounts of evaporated metal. High resolution TEM images in Figure 1 show that the film is continuous from at least 1 nm coverage; unlike for example Pd which shows isolated particle formation.Calculations for small Ti clusters confirm the tendency of Ti to wet the carbon surface. A single Ti atom strongly binds to graphene (2.64 eV), with Ti above a hexagon centre with short Ti-C bonds (2.24 Å), in good agreement with previous studies 10 . We have examined a range of 2D and 3D structures for Ti n on 2 graphene (n=1-4). For each cluster size the most stable structure is planar parallel to the graphene (see Figure 2). This is in contrast to Ti 4 in the gas phase where we find the most stable form is tetrahedral, in agreement with previous Ti cluster calculations 11 . A continuous monolayer of epitaxial Ti forms a buckled layer on average 2.0 Å above the graphitic layer, with Ti-C distances of 2.13 Å or 2.39 Å depending on whether the Ti atom lies above C atoms or hexagon centres respectively. In this case our binding energy is 5.43 eV/Ti atom. Our calculated barrier for Ti diffusion on the graphitic surface is 0.75 eV, as compared to ~0.1eV for Au and Pd. Thus while a simple first order Arhennius type equation with the Debye attempt frequency (10 13 Hz) suggests that isolated Au or Pd atoms on the graphitic surface at room temperature will be moving...

show abstract

“…The oxidation process may vary for different methods, e.g. in reactive-layer-assisted deposition (RLAD), Ti is evaporated onto a Au(111) substrate pre-deposited with a layer of H 2 O or N 2 O and post-annealing then gives rise to TiO x structures [23,24]. RLAD has also been reported for the CeO x /Au(111) system where a pre-deposited H 2 O or NO 2 layer was used [25].…”

Section: Thin Film Growthmentioning

confidence: 99%

Ultrathin Oxide Films on Au(111) Substrates

Castell

2016

Oxide Materials at the Two-Dimensional Limit

View full text Add to dashboard Cite

The Au(111) surface is an excellent substrate for the growth of ultrathin oxide films. Although it is chemically relatively inert, the high electronegativity of Au tends to give rise to strong interactions between the oxide film and the substrate via charge transfer processes. Many new surface oxide structures with unique properties have been observed in ultrathin film form that have no analogues as bulk crystal terminations. Abbreviations 2D

show abstract

Formation of TiO₂ Nanoparticles by Reactive-Layer-Assisted Deposition and Characterization by XPS and STM

Cited by 265 publications

References 24 publications

Effect of Synthesis on Quality, Electronic Properties and Environmental Stability of Individual Monolayer Ti₃C₂ MXene Flakes

Effect of Synthesis on Quality, Electronic Properties and Environmental Stability of Individual Monolayer Ti₃C₂ MXene Flakes

The Role of Oxygen at the Interface between Titanium and Carbon Nanotubes

Ultrathin Oxide Films on Au(111) Substrates

Contact Info

Product

Resources

About

Formation of TiO2 Nanoparticles by Reactive-Layer-Assisted Deposition and Characterization by XPS and STM

Cited by 265 publications

References 24 publications

Effect of Synthesis on Quality, Electronic Properties and Environmental Stability of Individual Monolayer Ti3C2 MXene Flakes

Effect of Synthesis on Quality, Electronic Properties and Environmental Stability of Individual Monolayer Ti3C2 MXene Flakes

The Role of Oxygen at the Interface between Titanium and Carbon Nanotubes

Ultrathin Oxide Films on Au(111) Substrates

Contact Info

Product

Resources

About

Formation of TiO₂ Nanoparticles by Reactive-Layer-Assisted Deposition and Characterization by XPS and STM

Effect of Synthesis on Quality, Electronic Properties and Environmental Stability of Individual Monolayer Ti₃C₂ MXene Flakes

Effect of Synthesis on Quality, Electronic Properties and Environmental Stability of Individual Monolayer Ti₃C₂ MXene Flakes