Transformation of hydrogen titanate nanoribbons to TiO₂ nanoribbons and the influence of the transformation strategies on the photocatalytic performance

• Melita Rutar,
• Nejc Rozman,
• Matej Pregelj,
• Carla Bittencourt,
• Romana Cerc Korošec,
• Andrijana Sever Škapin,
• Aleš Mrzel,
• Srečo D. Škapin and
• Polona Umek

Beilstein J. Nanotechnol. 2015, 6, 831–844, doi:10.3762/bjnano.6.86

• precursor HTiNRs is 3.65 eV and, as expected, the transformation to TiO2 NRs resulted in a narrowing of this band gap. Table 2 summarizes the band gaps of the selected TiO2 NR samples. In the set of samples calcined in air the band gap narrowed by about 0.2 eV. A slightly more pronounced effect is observed

• reflectance into the absorbance [46]. The optical band-gaps energy (Eg) was determined from the wavelength at which the tangent of the absorbance line intersected the abscissa coordinate. The chemical analysis of the sodium content was done using a FE-SEM equipped with an energy dispersive X-ray spectrometry

X-ray photoelectron spectroscopy of graphitic carbon nanomaterials doped with heteroatoms

• Toma Susi,
• Thomas Pichler and
• Paola Ayala

Beilstein J. Nanotechnol. 2015, 6, 177–192, doi:10.3762/bjnano.6.17

• indices (n,m). In single-walled carbon nanotubes, quantum confinement of the electronic wave function around the circumference of the tube results in one third of the tubes being metallic (when n − m = 3 × integer), while the remaining two thirds are semiconducting with band gaps proportional to their

Growth evolution and phase transition from chalcocite to digenite in nanocrystalline copper sulfide: Morphological, optical and electrical properties

• Priscilla Vasthi Quintana-Ramirez,
• Ma. Concepción Arenas-Arrocena,
• José Santos-Cruz,
• Marina Vega-González,
• Omar Martínez-Alvarez,
• Víctor Manuel Castaño-Meneses,
• Laura Susana Acosta-Torres and
• Javier de la Fuente-Hernández

Beilstein J. Nanotechnol. 2014, 5, 1542–1552, doi:10.3762/bjnano.5.166

• is clear, that the deficiencies of copper generate a displacement or shift of the optical absorption, which is consistent to the transition of the phases. The energy band gaps of the samples were computed by the Tauc plot for direct transition (Figure 5). The indirect plot (inset) did not present a

• towards low energies is observed in the CuxS samples synthesized in the range from 230 to 260 °C. Direct band gaps of copper sulfide in a) amorphous phase obtained by aqueous synthesis and b) crystalline phases from organic media. Indirect band gap plots are included as an inset in all plots. The clear

Sublattice asymmetry of impurity doping in graphene: A review

• James A. Lawlor and
• Mauro S. Ferreira

Beilstein J. Nanotechnol. 2014, 5, 1210–1217, doi:10.3762/bjnano.5.133

• , comes from matching tight binding and DFT band structure results, a method which is known to systematically underestimate such band gaps. Nevertheless, the band gap obtained can be expected to be much below that required for a GFET device. In-depth DFT calculations by Hou et al. [44] found that the

Functionalized nanostructures for enhanced photocatalytic performance under solar light

• Liejin Guo,
• Dengwei Jing,
• Maochang Liu,
• Yubin Chen,
• Shaohua Shen,
• Jinwen Shi and
• Kai Zhang

Beilstein J. Nanotechnol. 2014, 5, 994–1004, doi:10.3762/bjnano.5.113

• ]. Regarding the stability, oxide photocatalysts would be better than sulfide and nitride photocatalysts [42]. Regrettably, oxide semiconductors frequently possess either low conduction band positions or wide band gaps, which seriously impair their suitability as photocatalysts for hydrogen production [43

• junction-free semiconductors [66]. Depending on the band gaps and the electronic affinity of semiconductors, semiconductor heterostructures can be divided into three different cases: type-I, type-II and type-III band alignment [67]. In a type-II band alignment, the band offsets in the conduction and

Growth and characterization of CNT–TiO₂ heterostructures

• Yucheng Zhang,
• Ivo Utke,
• Johann Michler,
• Gabriele Ilari,
• Marta D. Rossell and
• Rolf Erni

Beilstein J. Nanotechnol. 2014, 5, 946–955, doi:10.3762/bjnano.5.108

• outer shells, i.e., excitations from the valence band to the conduction band. Hence, the low-loss signal contains information about the band structure of the specimen, and has been used to determine the band gaps of semiconductors [41]. Based on a dielectric model, the dielectric function can be

Effects of the preparation method on the structure and the visible-light photocatalytic activity of Ag₂CrO₄

• Difa Xu,
• Shaowen Cao,
• Jinfeng Zhang,
• Bei Cheng and
• Jiaguo Yu

Beilstein J. Nanotechnol. 2014, 5, 658–666, doi:10.3762/bjnano.5.77

• particle size among the three samples. The indirect band gaps of the Ag2CrO4 samples are calculated according to the Kubelka–Munk (KM) method by the following equation [62]: where α is the absorption coefficient, hν is the photon energy, Eg is the indirect band gap, and A is a constant. As shown in the

• inset of Figure 5, the calculated band gap energies of the S-M, S-P and S-H samples are 1.85, 1.82 and 1.76 eV, respectively (Table 1). In spite of the little difference of the band gaps, it is clear that all the three Ag2CrO4 samples exhibit an excellent visible-light response for photocatalytic

• corresponding FFT image. Nitrogen adsorption-desorption isotherms and corresponding pore size distribution curves (inset) of Ag2CrO4 samples prepared by different methods: (a) microemulsion, (b) precipitation, and (c) hydrothermal. UV–visible diffuse reflectance spectra, the calculated band gaps (upper right

Mesoporous cerium oxide nanospheres for the visible-light driven photocatalytic degradation of dyes

• Subas K. Muduli,
• Songling Wang,
• Shi Chen,
• Chin Fan Ng,
• Cheng Hon Alfred Huan,
• Tze Chien Sum and
• Han Sen Soo

Beilstein J. Nanotechnol. 2014, 5, 517–523, doi:10.3762/bjnano.5.60

• , including Ce2O3 and Ce7O12, are known to have band gaps in the visible region [13][19][20][21]. Our team has maintained a keen interest in alternative affordable, earth-abundant, visible light absorbing metal oxides to be used in two-photon ‘Z-schemes’ for dye-sensitized photoelectrosynthesis cells (DSPECs

Dye-sensitized Pt@TiO₂ core–shell nanostructures for the efficient photocatalytic generation of hydrogen

• Jun Fang,
• Lisha Yin,
• Shaowen Cao,
• Yusen Liao and
• Can Xue

Beilstein J. Nanotechnol. 2014, 5, 360–364, doi:10.3762/bjnano.5.41

• ca. 380 nm can be attributed to the band edge absorption of anatase TiO2. The band gaps of both samples are calculated according to the modified Kubelka–Munk function vs the energy the of absorbed light, E [18]. And the plots shown in the inset of Figure 3 reveal the band gap value as 3.3 eV for Pt

Core level binding energies of functionalized and defective graphene

• Toma Susi,
• Markus Kaukonen,
• Paula Havu,
• Mathias P. Ljungberg,
• Paola Ayala and
• Esko I. Kauppinen

Beilstein J. Nanotechnol. 2014, 5, 121–132, doi:10.3762/bjnano.5.12

• approach since the screening of the core hole is very efficient and the extra electron would be introduced at the Fermi level; however, for systems with large band gaps, this procedure could lead to large errors. Although the energy will depend on the exchange–correlation functional being used, the method

Study of mesoporous CdS-quantum-dot-sensitized TiO₂ films by using X-ray photoelectron spectroscopy and AFM

• Mohamed N. Ghazzal,
• Robert Wojcieszak,
• Gijo Raj and
• Eric M. Gaigneaux

Beilstein J. Nanotechnol. 2014, 5, 68–76, doi:10.3762/bjnano.5.6

• essential parameters such as compounds energy band gaps and the Scofield cross sections were taken from [28] and [29] respectively. The very small CdS particles were observed for the 1×CdS/TiO2 and 3×CdS/TiO2 samples (smaller than 1 nm). In contrast, the 15×CdS/TiO2 sample (15 deposition cycles) showed the

Many-body effects in semiconducting single-wall silicon nanotubes

• Wei Wei and
• Timo Jacob

Beilstein J. Nanotechnol. 2014, 5, 19–25, doi:10.3762/bjnano.5.2

• approximation and Bethe–Salpeter equation. In these studied structures, i.e., (4,4), (6,6) and (10,0) SiNTs, self-energy effects are enhanced giving rise to large quasi-particle (QP) band gaps due to the confinement effect. The strong electron−electron (e−e) correlations broaden the band gaps of the studied

• Figure 1, are studied. It has been identified that the self-energy effects are evident in the studied SiNTs, giving rise to large QP band gaps, and the excitonic effects distinctly modify optical absorption properties, resulting in the formation of bound excitons with considerable binding energies. The

• optical responses are characterized by resonant excitations [54]. Figure 2 shows the band structures of (4,4), (6,6) and (10,0) SiNTs, which indicate semiconducting character as band gaps appear. In case of armchair (4,4) SiNT, the band structure indicates an indirect band gap of 0.32 eV at Z point and a

Synthesis of indium oxi-sulfide films by atomic layer deposition: The essential role of plasma enhancement

• Cathy Bugot,
• Nathanaëlle Schneider,
• Daniel Lincot and
• Frédérique Donsanti

Beilstein J. Nanotechnol. 2013, 4, 750–757, doi:10.3762/bjnano.4.85

• pyrolysis technique, Maha et al. have inserted sulfur atoms in In2O3 thin films and obtained optical band gaps in the range from 3.85 to 3.96 eV [18]. Thus, based on our previous results and those studies, we became interested in adjusting the optical properties of In2S3 by incorporating oxygen atoms while

• their respective absorption spectra (Figure 6a). The values are plotted as a function of the ratio of In2O3 cycles in Figure 6b. The maximum value corresponds to the theoretical optical gap of In2O3 [30]. The optical band gaps vary from 2.2 ± 0.1 eV for pure In2S3 to 3.3 ± 0.1 eV for In2(S,O)3 and

• [29] where α is the absorption coefficient and t is the film thickness. Figure 3 shows absorption spectra of the thin films. They are presented in the form of (α)0.5 = f(E), which is linear for indirect band gap materials and allows for the determination of the optical transition. The optical band

Photocatalytic antibacterial performance of TiO₂ and Ag-doped TiO₂ against S. aureus. P. aeruginosa and E. coli

• Kiran Gupta,
• R. P. Singh,
• Ashutosh Pandey and
• Anjana Pandey

Beilstein J. Nanotechnol. 2013, 4, 345–351, doi:10.3762/bjnano.4.40

• case, for an indirect band gap, the value of n is ½ [17]. The variation of (αhν)1/2 with photon energy is shown in Figure 4. The band gaps were determined to be about 3.15 eV, 2.8 eV and 2.7 eV for annealed TiO2, Ag–TiO2 (3%) and Ag–TiO2 (7%), respectively, by extrapolation of the linear portion of the

Electronic and transport properties of kinked graphene

• Jesper Toft Rasmussen,
• Tue Gunst,
• Peter Bøggild,
• Antti-Pekka Jauho and
• Mads Brandbyge

Beilstein J. Nanotechnol. 2013, 4, 103–110, doi:10.3762/bjnano.4.12

• , known as a graphene antidot lattice (GAL) [7], or a nanoscale mesh of holes [8][9][10] can have neck widths [10][11] down to 5 nm corresponding to band gaps of the order of 1 eV [2]. Graphene consists entirely of surface atoms and is thus exceedingly sensitive to the surroundings. In particular, the van

• . Generally, we find that the main behaviour of the transmission is controlled by the connecting sections S2, S4, i.e., there is a good correspondence between the side section band gaps and the transmission gaps. Conclusion The presented investigations show that linear kink-line structures may form in

• two close-by parallel kinks form a pseudo graphene nanoribbon with similar behaviour of the electronic structure to that for isolated nanoribbons. The transmission function displays transport gap features corresponding to the isolated nanoribbon band gaps. The present work thus suggests that it may be

Nanostructure-directed chemical sensing: The IHSAB principle and the dynamics of acid/base-interface interaction

• James L. Gole and
• William Laminack

Beilstein J. Nanotechnol. 2013, 4, 20–31, doi:10.3762/bjnano.4.3

• when the analyte interacts with the surface. How does the change in the bands occur? How does this affect the band gap? The prediction of the electronic properties, especially the band gaps, is closely tied to the actual structure of the interface. Where does the analyte bind to the interface? What

Structural and electronic properties of oligo- and polythiophenes modified by substituents

• Simon P. Rittmeyer and
• Axel Groß

Beilstein J. Nanotechnol. 2012, 3, 909–919, doi:10.3762/bjnano.3.101

• monomers and dimers, they hardly influence the band gap of polythiophene. In contrast, phenyl-substituted polythiophenes as well as vinyl-bridged polythiophene derivatives exhibit drastically modified band gaps. These effects cannot be explained by simple electron removal or addition, as calculations for

• charged polythiophenes demonstrate. Keywords: band gaps; conducting polymers; density functional theory calculations; molecular electronics; oligothiophenes; Introduction Since the first report about the electrical conductivity of doped polyacetylene (PA) in 1977 [1], significant efforts have been spent

• cell. In order to preserve the electric neutrality of the cell, a compensating background charge is generated by default. As we are interested in the HOMO–LUMO gap of oligothiophenes and the band gaps of polythiophenes, we have to be concerned with the well-known deficiency of DFT using current-day GGA

Horizontal versus vertical charge and energy transfer in hybrid assemblies of semiconductor nanoparticles

• Gilad Gotesman,
• Rahamim Guliamov and
• Ron Naaman

Beilstein J. Nanotechnol. 2012, 3, 629–636, doi:10.3762/bjnano.3.72

• , and this shift, following the linker adsorption, has not been observed (Figure S5b, Supporting Information File 1). The charge transfer process (electron–hole separation) across the NP layers may occur because of slight differences in the NP sizes, which result in variations in the energy band gaps

Models of the interaction of metal tips with insulating surfaces

• Thomas Trevethan,
• Matthew Watkins and
• Alexander L. Shluger

Beilstein J. Nanotechnol. 2012, 3, 329–335, doi:10.3762/bjnano.3.37

• exhibit rumpling, with the anions protruding from the surface plane. The corrugation of the NaCl surface is approximately 0.1 Å and 0.04 Å in MgO. The one-electron band gaps for the NaCl surface at 4.9 eV, and for the MgO surface at 3.6 eV, are underestimated, which is typical for PBE calculations. The

Aerosol assisted fabrication of two dimensional ZnO island arrays and honeycomb patterns with identical lattice structures

• Mitsuhiro Numata and
• Yoshihiro Koide

Beilstein J. Nanotechnol. 2010, 1, 71–74, doi:10.3762/bjnano.1.9

• the manipulation of light using photonic band gaps (PBG) created in an air-hole type 2D PhC, in which a material with relatively high refractive indices are periodically arranged on a flat substrate in open space. For example, PBGs have been observed with arrays of spherical polystyrene, silica

On the reticular construction concept of covalent organic frameworks

• Binit Lukose,
• Agnieszka Kuc,
• Johannes Frenzel and
• Thomas Heine

Beilstein J. Nanotechnol. 2010, 1, 60–70, doi:10.3762/bjnano.1.8

• latter ones are only slightly modified compared to the high-symmetry forms, but show higher energetic stability. Experimental XRD patterns found in literature also support stackings with highest formation energies. All stacking forms vary in their interlayer separations and band gaps; however, their

• electronic densities of states (DOS) are similar and not significantly different from that of a monolayer. The band gaps are found to be in the range of 1.7–4.0 eV. COFs built of building blocks with a greater number of aromatic rings have smaller band gaps. Keywords: covalent organic frameworks; DFTB

• 0.40 kJ•mol−1, respectively; hence supporting the endothermic nature of the condensation reaction and is in reasonable agreement with our DFTB results (Table 2). Electronic properties All COFs, including the reference structures, are semiconductors with their band gaps lying between 1.7 eV and 4.0 eV