Spectroscopic evidence of NOx formation and band-gap narrowing in N-doped TiO2 films grown by pulsed magnetron sputtering

Gago, R.; Redondo-Cubero, A.; Vinnichenko, M.; Lehmann, J.; Munnik, F.; Palomares, F. J.

doi:10.1016/j.matchemphys.2012.07.049

Cited by 18 publications

(16 citation statements)

References 53 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Otherwise, the TiO 2 :N layers are also amorphous after heating but with a low refractive index that is more according to an "anatase-like" shortrange arrangement. A nitrogen-induced transformation from rutile-like to anatase-like structures has been reported for other films that were X-ray amorphous as-grown on unheated substrates [21]. Here, analogous behavior has been observed in the asgrown samples and it becomes more pronounced after heating, when anatase vibrational modes can be found in the TiO 2 :N layer (Fig.…”

Section: Resultssupporting

confidence: 78%

“…In accordance with such statement, all the layers prepared with N 2 in the sputtering atmosphere have been found amorphous for the various oxygen proportions tested. In this sense, it has been reported that N incorporation induces some amorphization of the rutile structure conferring an anatase-like character [21]. This is Fig.…”

Section: Resultsmentioning

confidence: 83%

“…This is mainly because the sputtered layers are usually amorphous as-grown at room temperature. Then, some authors indicate that effective N-doping is achieved only after crystallization by increasing the substrate temperature or by post-deposition heating [12,21], whereas other researches show that an increasing N amount in the films can further reduce the gap energy although it prevents their crystallization [22,23].…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Influence of N-doping and air annealing on the structural and optical properties of TiO2 thin films deposited by reactive DC sputtering at room temperature

Guillén

Montero

Herrero

2015

Journal of Alloys and Compounds

View full text Add to dashboard Cite

Section: Resultssupporting

confidence: 78%

Section: Resultsmentioning

confidence: 83%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Influence of N-doping and air annealing on the structural and optical properties of TiO2 thin films deposited by reactive DC sputtering at room temperature

Guillén

Montero

Herrero

2015

Journal of Alloys and Compounds

View full text Add to dashboard Cite

“…The dominant A 101 reflection from the TiO 2 :N coating evidences that the addition of N under these conditions prevents rutile formation and yields a nearly single-phase anatase film. This effect was reported in detail in a previous publication by some of the present authors [20] and other groups [27][28][29]. In the Cr co-doped monolithic film, the structure displays a strong mixed-phase character where the rutile content is significantly higher than in the pure TiO 2 film.…”

Section: Sample Characterizationsupporting

confidence: 80%

“…In the latter case, a buffer TiO 2 :N films was initially grown (W Cr = 0 W) with a thickness up to several tens of nm's followed by the subsequent instant (bilayer coating) or gradual (gradient coating) increase in W Cr to produce the Cr-containing layer(s). The deposition was done at a substrate temperature, T s , of 300 • C to achieve high-quality anatase phase in TiO 2 :N films [20].…”

Section: Sample Preparationmentioning

confidence: 99%

Phase Selectivity in Cr and N Co-Doped TiO2 Films by Modulated Sputter Growth and Post-Deposition Flash-Lamp-Annealing

et al. 2019

View full text Add to dashboard Cite

In this paper, we report on the phase selectivity in Cr and N co-doped TiO 2 (TiO 2 :Cr,N) sputtered films by means of interface engineering. In particular, monolithic TiO 2 :Cr,N films produced by continuous growth conditions result in the formation of a mixed-phase oxide with dominant rutile character. On the contrary, modulated growth by starting with a single-phase anatase TiO 2 :N buffer layer, can be used to imprint the anatase structure to a subsequent TiO 2 :Cr,N layer. The robustness of the process with respect to the growth conditions has also been investigated, especially regarding the maximum Cr content (<5 at.%) for single-phase anatase formation. Furthermore, post-deposition flash-lamp-annealing (FLA) in modulated coatings was used to improve the as-grown anatase TiO 2 :Cr,N phase, as well as to induce dopant activation (N substitutional sites) and diffusion. In this way, Cr can be distributed through the whole film thickness from an initial modulated architecture while preserving the structural phase. Hence, the combination of interface engineering and millisecond-range-FLA opens new opportunities for tailoring the structure of TiO 2 -based functional materials.

show abstract

Directed Molecular Stacking for Engineered Fluorescent Three‐Dimensional Reduced Graphene Oxide and Coronene Frameworks

Mao

Cortezon‐Tamarit

et al. 2019

ChemistryOpen

View full text Add to dashboard Cite

Three-dimensional fluorescent graphene frameworks with controlled porous morphologies are of significant importance for practical applications reliant on controlled structural and electronic properties, such as organic electronics and photochemistry. Here we report a synthetically accessible approach concerning directed aromatic stacking interactions to give rise to new fluorogenic 3D frameworks with tuneable porosities achieved through molecular variations. The binding interactions between the graphene-like domains present in the in situ-formed reduced graphene oxide (rGO) with functional porphyrin molecules lead to new hybrids via an unprecedented solvothermal reaction. Functional free-base porphyrins featuring perfluorinated aryl groups or hexyl chains at their meso-and β-positions were employed in turn to act as directing entities for the assembly of new graphene-based and foam-like frameworks and of their corresponding coronene-based hybrids. Investigations in the dispersed phase and in thin-film by XPS, SEM and FLIM shed light onto the nature of the aromatic stacking within functional rGO frameworks (denoted rGOFs) which was then modelled semi-empirically and by DFT calculations. The pore sizes of the new emerging reduced graphene oxide hybrids are tuneable at the molecular level and mediated by the bonding forces with the functional porphyrins acting as the "molecular glue". Single crystal X-ray crystallography described the stacking of a perfluorinated porphyrin with coronene, which can be employed as a molecular model for understanding the local aromatic stacking order and charge transfer interactions within these rGOFs for the first time. This opens up a new route to controllable 3D framework morphologies and pore size from the Ångstrom to the micrometre scale. Theoretical modelling showed that the porosity of these materials is mainly due to the controlled inter-planar distance between the rGO, coronene or graphene sheets. The host-guest chemistry involves the porphyrins acting as guests held through π-π stacking, as demonstrated by XPS. The objective of this study is also to shed light into the fundamental localised electronic and energy transfer properties in these new molecularly engineered porous and fluorogenic architectures, aiming in turn to understand how functional porphyrins may exert stacking control over the notoriously disordered local structure present in porous reduced graphene oxide fragments. By tuning the porosity and the distance between the graphene sheets using aromatic stacking with porphyrins, it is also possible to tune the electronic structure of the final nanohybrid material, as indicated by FLIM experiments on thin films. Such nanohybrids with highly controlled pores dimensions and morphologies open the way to new design and assembly of storage devices and applications incorporating π-conjugated molecules and materials and their πstacks may be relevant towards selective separation membranes, water purification and biosensing applications.

show abstract

Spectroscopic evidence of NOx formation and band-gap narrowing in N-doped TiO2 films grown by pulsed magnetron sputtering

Cited by 18 publications

References 53 publications

Influence of N-doping and air annealing on the structural and optical properties of TiO2 thin films deposited by reactive DC sputtering at room temperature

Influence of N-doping and air annealing on the structural and optical properties of TiO2 thin films deposited by reactive DC sputtering at room temperature

Phase Selectivity in Cr and N Co-Doped TiO2 Films by Modulated Sputter Growth and Post-Deposition Flash-Lamp-Annealing

Directed Molecular Stacking for Engineered Fluorescent Three‐Dimensional Reduced Graphene Oxide and Coronene Frameworks

Contact Info

Product

Resources

About