High performance Ce-doped ZnO nanorods for sunlight-driven photocatalysis

• Bilel Chouchene,
• Tahar Ben Chaabane,
• Lavinia Balan,
• Emilien Girot,
• Kevin Mozet,
• Ghouti Medjahdi and
• Raphaël Schneider

Beilstein J. Nanotechnol. 2016, 7, 1338–1349, doi:10.3762/bjnano.7.125

• semiconductor photocatalyst owing to its availability, weak toxicity, stability and relatively good resistance to photocorrosion [2][3][4][5][6][7]. However, to efficiently use ZnO in practice as an air and water decontamination agent, two drawbacks should be overcome. First, ZnO is a wide bandgap material (Eg

• significant attention, especially with cerium. Ce3+ possesses shielded 4f levels, which allow various well-defined narrow optical transitions between the spin-orbit levels and thus split the bandgap of ZnO into sub-gaps. For this reason, Ce3+ is generally doped or associated to ZnO to improve the luminescence

• increasing Ce concentrations. The redshift in absorption probably originates from sub-bandgap transitions originating from Ce doping [34][54]. These electronic transitions from the VB of ZnO to the Ce energy levels require less energy than that of the VB to the CB of ZnO. Reflectance spectra have been

Reasons and remedies for the agglomeration of multilayered graphene and carbon nanotubes in polymers

• Rasheed Atif and
• Fawad Inam

Beilstein J. Nanotechnol. 2016, 7, 1174–1196, doi:10.3762/bjnano.7.109

• , the nanotube exhibits electron transport properties of a metal, while it behaves as a semiconductor if above condition is not satisfied. The semiconducting CNTs have varying bandgaps [36]. The bandgap for semi-conducting CNT is inversely proportional to the diameter of nanotube. The values of about

• 1.8 eV and 0.18 eV have been reported of bandgap for small and large diameters nanotubes, respectively [2]. About two third SWNT behave as semiconductor while remaining as metals. It is interesting to note that in MWNT, each graphene layer can have different chirality [40]. Unfortunately, all the

Manufacturing and investigation of physical properties of polyacrylonitrile nanofibre composites with SiO₂, TiO₂ and Bi₂O₃ nanoparticles

• Tomasz Tański,
• Wiktor Matysiak and
• Barbara Hajduk

Beilstein J. Nanotechnol. 2016, 7, 1141–1155, doi:10.3762/bjnano.7.106

• nm. The device was controlled by using the SpectraRay 3 software. The measurements of ψ and Δ were carried out under a constant falling light angle of 70°. The measurements of the absorbance of the obtained materials, from which the value of the data bandgap width was specified, were carried out

Photocurrent generation in carbon nanotube/cubic-phase HfO₂ nanoparticle hybrid nanocomposites

• Protima Rauwel,
• Augustinas Galeckas,
• Martin Salumaa,
• Frédérique Ducroquet and
• Erwan Rauwel

Beilstein J. Nanotechnol. 2016, 7, 1075–1085, doi:10.3762/bjnano.7.101

• dimensionality of nanoparticles; among established methods ensuring control of both size and shape is the nonaqueous sol–gel route [18][19]. In our previous studies, a strong photoluminescence in the visible range was observed from HfO2 nanoparticles under below-bandgap excitation [20][21] and attributed to

• typically the vHS-related bandgap transitions are observed in CNTs, such as E22 from the semiconducting SWCNT and E11 from the metallic SWCNT [39]. At higher photon energies, a broad absorption band emerging at around 4.5 eV is likely due to the π-plasmon resonance [40][41]. This feature gradually merges

• ] and put alongside for comparison in Figure 2. The absorption thresholds marked by the dashed lines in the Tauc plot in Figure 2b are consistent with the reported bandgap energies for hafnia (theoretical 4.9–5.7 eV and experimental 5–6 eV [14][42]) as well as with defect-related absorption showing up

Optical absorption signature of a self-assembled dye monolayer on graphene

• Tessnim Sghaier,
• Sylvain Le Liepvre,
• Céline Fiorini,
• Ludovic Douillard and
• Fabrice Charra

Beilstein J. Nanotechnol. 2016, 7, 862–868, doi:10.3762/bjnano.7.78

• changes of the optical bandgap. However, alkyl chains present here should reduce such interactions by maintaining the conjugated moiety at a larger distance from graphene. This is substantiated by the preservation of the absorption line-shape and the balance between vibronic contributions. This also means

Determination of Young’s modulus of Sb₂S₃ nanowires by in situ resonance and bending methods

• Liga Jasulaneca,
• Raimonds Meija,
• Alexander I. Livshits,
• Juris Prikulis,
• Subhajit Biswas,
• Justin D. Holmes and
• Donats Erts

Beilstein J. Nanotechnol. 2016, 7, 278–283, doi:10.3762/bjnano.7.25

• ] applications. It has also been studied as a photonic bandgap material in the visible region of the electromagnetic spectrum [12]. Synthesis and characterization of various Sb2S3 nanostructures including dendrites [13], nanorods [14], whiskers [15], nanowires (NWs) [16][17] and nanotubes [18] have been reported

Current-induced runaway vibrations in dehydrogenated graphene nanoribbons

• Rasmus Bjerregaard Christensen,
• Jing-Tao Lü,
• Per Hedegård and
• Mads Brandbyge

Beilstein J. Nanotechnol. 2016, 7, 68–74, doi:10.3762/bjnano.7.8

• study since its discovery in 2004 [1]. Due to the strong σ-bonding between carbon atoms, graphene has a very high thermal conductivity, and can potentially sustain much higher current intensities than other materials. Graphene nanoribbons (GNR) exhibit a bandgap opening due to quantum confinement in the

Large area scanning probe microscope in ultra-high vacuum demonstrated for electrostatic force measurements on high-voltage devices

• Urs Gysin,
• Thilo Glatzel,
• Thomas Schmölzer,
• Adolf Schöner,
• Sergey Reshanov,
• Holger Bartolf and
• Ernst Meyer

Beilstein J. Nanotechnol. 2015, 6, 2485–2497, doi:10.3762/bjnano.6.258

• bandgap of SiC which is in the range of Eg,SiC = 3.25 eV. Or, more accurately, it should correspond to the built-in potential Vb which one could ideally expect across the interface. The theoretical Vb calculates as [45]: where k is the Boltzmann constant, T the temperature, q the elementary charge, and NA

• also affecting the electronic structure at surfaces [56]. Especially carbon clusters are responsible for donor states in the lower part of the bandgap as well as a continuum of donor- and acceptor-type states in the central part of the band gap. Thus, the measurements presented here fit perfectly in

• defects is valid for the p-type case. Under illumination electrons are excited from the valence band to the acceptor-type defects at mid bandgap. Consequently, the charge carrier density at the surface is changed and the band bending is reduced, however, only until all acceptor type defect states are

Surfactant-controlled composition and crystal structure of manganese(II) sulfide nanocrystals prepared by solvothermal synthesis

• Elena Capetti,
• Anna M. Ferretti,
• Vladimiro Dal Santo and
• Alessandro Ponti

Beilstein J. Nanotechnol. 2015, 6, 2319–2329, doi:10.3762/bjnano.6.238

• the surfactants adsorbed on the NCs. Keywords: manganese oxide; manganese sulfide; nanocrystal; polymorphism control; solvothermal synthesis; sulfur; surfactant; Introduction Manganese(II) sulfide (MnS) is a wide bandgap (Eg ≈ 3 eV) [1], p-type, antiferromagnetic semiconductor that crystallizes in

Nitrogen-doped graphene films from chemical vapor deposition of pyridine: influence of process parameters on the electrical and optical properties

• Andrea Capasso,
• Theodoros Dikonimos,
• Francesca Sarto,
• Alessio Tamburrano,
• Giovanni De Bellis,
• Maria Sabrina Sarto,
• Giuliana Faggio,
• Angela Malara,
• Giacomo Messina and
• Nicola Lisi

Beilstein J. Nanotechnol. 2015, 6, 2028–2038, doi:10.3762/bjnano.6.206

• ], polymers [20], atoms [21] and molecular functional groups [22]) that alter its electronic properties and can also, in principle, open a bandgap, giving graphene semiconductor properties. In an alternative way, graphene can be doped by substitution, i.e., by inserting heterogeneous atoms into the lattice

Possibilities and limitations of advanced transmission electron microscopy for carbon-based nanomaterials

• Xiaoxing Ke,
• Carla Bittencourt and
• Gustaaf Van Tendeloo

Beilstein J. Nanotechnol. 2015, 6, 1541–1557, doi:10.3762/bjnano.6.158

• to the modification of its intrinsic physical properties, including bandgap variation and quantum transport disturbance. Therefore, a detailed study of how the atomic structure responds to strain has contributed to the fundamental understanding of the physics of CNTs and other related nanostructures

Current–voltage characteristics of manganite–titanite perovskite junctions

• Benedikt Ifland,
• Patrick Peretzki,
• Birte Kressdorf,
• Philipp Saring,
• Andreas Kelling,
• Michael Seibt and
• Christian Jooss

Beilstein J. Nanotechnol. 2015, 6, 1467–1484, doi:10.3762/bjnano.6.152

• limit of VOC is given by the smaller bandgap, that is, Eg is replaced by min(Eg1, Eg2). In the presence of a band discontinuity, the energy barrier/spike EB which is generated at the heterointerface determines the upper limit of VOC for T = 0 K [42]. Equivalent circuit A real photovoltaic device is

Electron and heat transport in porphyrin-based single-molecule transistors with electro-burnt graphene electrodes

• Hatef Sadeghi,
• Sara Sangtarash and
• Colin J. Lambert

Beilstein J. Nanotechnol. 2015, 6, 1413–1420, doi:10.3762/bjnano.6.146

• correct location relative to the Fermi energy of the electrodes. However, the LUMO (HOMO) energy level is almost equivalent to the negative of the electron affinity energy (ionization potential). Therefore, we estimate the bandgap, Eg, of the molecule (sometimes called additional energy) by computing the

Electronic interaction in composites of a conjugated polymer and carbon nanotubes: first-principles calculation and photophysical approaches

• Florian Massuyeau,
• Jany Wéry,
• Jean-Luc Duvail,
• Serge Lefrant,
• Abu Yaya,
• Chris Ewels and
• Eric Faulques

Beilstein J. Nanotechnol. 2015, 6, 1138–1144, doi:10.3762/bjnano.6.115

• bandgap depending of their chirality. This fundamental physical difference will have tremendous importance as concerns the electronic coupling, the energy transfer and the migration of excitons between the semi-conducting polymer and the nanotubes [15]. Therefore, the results are compared with original

• Hartwigsen, Goedecker and Hütter relativistic pseudopotentials [24]. A Fermi temperature smearing for the electron population of kT = 0.001 eV was used. While the tubes modelled here have smaller diameters than those used in the experiment (for computational efficiency), we note that the reduced bandgap due

• to LDA to some extent counteracts what would otherwise be an overestimation in the modelling of the band gap of the experimental tubes. Specifically, we note that our calculated bandgap for the (7,0) nanotube of 0.08 eV is considerably underestimated compared to experiments, due to the well-known

Morphology control of zinc oxide films via polysaccharide-mediated, low temperature, chemical bath deposition

• Florian Waltz,
• Hans-Christoph Schwarz,
• Andreas M. Schneider,
• Stefanie Eiden and
• Peter Behrens

Beilstein J. Nanotechnol. 2015, 6, 799–808, doi:10.3762/bjnano.6.83

• during the first CBD step, allow the formation of a more dense ZnO layer during the final CBD. Consequently, as the total material supply is limited, axial growth is diminished, that is, the films become thinner. Electrical properties of the films ZnO is a semiconductor with a direct bandgap of 3.37 eV

• properties were determined under UV irradiation corresponding to the bandgap energy (370 nm). The values of the sheet resistance as well as the specific resistance of completely processed ZnO films after the second CBD are listed in Table 2. The sheet resistance of our films was above 1 kΩ/sq and the sheet

Chains of carbon atoms: A vision or a new nanomaterial?

• Florian Banhart

Beilstein J. Nanotechnol. 2015, 6, 559–569, doi:10.3762/bjnano.6.58

• elementary period of the undistorted chain a is doubled to 2a. The calculated length of the double bond in cumulene is 1.282 Å; the single and triple bond lengths in polyyne are 1.265 Å and 1.301 Å, respectively [26]. The alternating shorter and longer bonds in polyyne result in an electronic bandgap. The

• gain in electronic energy due to the formation of a bandgap outweighs the increase in strain energy [27]. However, the gain in energy of the (unstrained) polyyne structure is only 70 meV/atom [28]. This is a small difference in comparison to the total cohesive energy of the order of 7.0 eV/atom in a

• bandgap. Simulations show that a strain of 10% leads to a bandgap of 1.5–3.0 eV, depending on the approximation (DFT, GW) [19][23]. The electrical properties of chains can only be measured by contacts through single atoms. The bonding characteristics at this particular point are of paramount importance

Bright photoluminescence from ordered arrays of SiGe nanowires grown on Si(111)

• D. J. Lockwood,
• N. L. Rowell,
• A. Benkouider,
• A. Ronda,
• L. Favre and
• I. Berbezier

Beilstein J. Nanotechnol. 2014, 5, 2498–2504, doi:10.3762/bjnano.5.259

• occurring within the NWs. Keywords: bandgap; germanium; nanowires; near field; silicon; photoluminescence; Introduction Semiconductor nanowires (NWs) are thought of as promising building blocks for opto-electronic devices that exploit their novel electronic band structures generated by two-dimensional (2D

Electrical contacts to individual SWCNTs: A review

• Wei Liu,
• Christofer Hierold and
• Miroslav Haluska

Beilstein J. Nanotechnol. 2014, 5, 2202–2215, doi:10.3762/bjnano.5.229

• ambipolar and to fully n-type. Assuming the intrinsic Fermi level of SWCNTs is in the middle of the band gap (i.e., the intrinsic work function of the SWCNTs is approximated as the electron affinity plus half of the bandgap: ), the corresponding Schottky barrier height for a metal with a low work function

Silicon and germanium nanocrystals: properties and characterization

• Ivana Capan,
• Alexandra Carvalho and
• José Coutinho

Beilstein J. Nanotechnol. 2014, 5, 1787–1794, doi:10.3762/bjnano.5.189

• passivation, although in the chlorinated Si NCs some fall off the narrower gap. Functionalisation with chlorine, nitrogen and fluorine was also found to be an effective way to control the bandgap of nanodiamonds [68]. Nanocrystals functionalized with organic groups have so far only been considered in a

Numerical investigation of the effect of substrate surface roughness on the performance of zigzag graphene nanoribbon field effect transistors symmetrically doped with BN

• Majid Sanaeepur,
• Arash Yazdanpanah Goharrizi and
• Mohammad Javad Sharifi

Beilstein J. Nanotechnol. 2014, 5, 1569–1574, doi:10.3762/bjnano.5.168

• device engineers [3][4]. Unmodified graphene sheets do not have a band gap, therefore graphene transistors are not suitable for digital applications for which a minimum band gap of 360 meV is needed [5][6]. Nevertheless, graphene nanoribbons (GNRs) smaller than 15 nm show a bandgap inversely proportional

An insight into the mechanism of charge-transfer of hybrid polymer:ternary/quaternary chalcopyrite colloidal nanocrystals

• Parul Chawla,
• Son Singh and
• Shailesh Narain Sharma

Beilstein J. Nanotechnol. 2014, 5, 1235–1244, doi:10.3762/bjnano.5.137

• in Figure 3C(a–c), which shows the enhancement of the optical bandgap (as calculated from the Tauc’s plot involving the absorption coefficient, α and the photon energy hν) from CISe to CZTSe. The bandgap values of pristine CISe, CIGSe and CZTSe are ≈1.03 eV, 1.1 eV and 1.15 eV, respectively (Figure

•  3C(a–c)). As can be observed from Figure 3D(a–c), the enhanced bandgap values for CISe, CIGSe and CZTSe are 1.26 eV, 1.18 eV and 1.15 eV, respectively. During prolonged light exposure there might occur a reorientation and reformation of bonds depending on the stability of the nanocrystals. Thus

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

• concentration of dopants exists, as mentioned in the theory section, which would limit the available bandgap below the threshold needed for future use in GFET devices. Currently all experimental reports on sublattice asymmetry have very low concentrations of dopants around 0.3%, so it should be feasible to test

• the current state of experimental and theoretical research in sublattice asymmetric nitrogen doped graphene. Not only are such systems now able to be synthesised in the lab, we have seen that this area shows promise attaining graphene-based FET devices due to the opening of a bandgap whilst

Fringe structures and tunable bandgap width of 2D boron nitride nanosheets

• Peter Feng,
• Muhammad Sajjad,
• Eric Yiming Li,
• Hongxin Zhang,
• Jin Chu,
• Ali Aldalbahi and
• Gerardo Morell

Beilstein J. Nanotechnol. 2014, 5, 1186–1192, doi:10.3762/bjnano.5.130

• bandgap width of atomic-thin boron nitride nanosheets (BNNSs). BNNSs are synthesized by using digitally controlled pulse deposition techniques. The nanoscale morphologies of BNNSs are characterized by using scanning electron microscope (SEM), and transmission electron microscopy (TEM). In general, the

• efficiently control bandgap width. The characterizations are based on Raman scattering spectroscopy, X-ray diffraction (XRD), and FTIR transmittance spectra. Red shifts of spectral lines are clearly visible after the functionalization, indicating the bandgap width of the BNNSs has been changed. However

• , simple treatments with hydrogen gas do not affect the bandgap width of the BNNSs. Keywords: boron nitride sheets; fringe patterns; functionalization; tunable bandgap width; Introduction The recent successful investigation of graphene has stimulated interest in atomically thin boron nitride sheets [1][2

Characterization and photocatalytic study of tantalum oxide nanoparticles prepared by the hydrolysis of tantalum oxo-ethoxide Ta₈(μ₃-O)₂(μ-O)₈(μ-OEt)₆(OEt)₁₄

• Subia Ambreen,
• N D Pandey,
• Peter Mayer and
• Ashutosh Pandey

Beilstein J. Nanotechnol. 2014, 5, 1082–1090, doi:10.3762/bjnano.5.121

• the organic dye rhodamine B. Keywords: bandgap; tantalum-oxo-ethoxide; Tauc plot; tantalum pentoxide (Ta2O5); Introduction Metal alkoxides, being excellent precursors in the sol–gel process for preparation of metal oxides have attained huge attention of researchers. Several attempts have been made

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

• high crystallinity, high surface area and unique microstructure [63]. As the crystal size of the semiconductor is close to the exciton Bohr radius, its bandgap can be enlarged with a reduced crystal size due to the quantum confinement effect. Therefore, we have synthesized Co3O4 quantum dots (3–4 nm

• Co3O4 is not negative enough to reduce H+. Compared with bulk Co3O4, Co3O4 quantum dots have a wider bandgap. Valence-band XPS spectra showed that the valance band maxima (VBM) of Co3O4 quantum dots and bulk Co3O4 are almost at the same position, implying that the enlarged bandgap of Co3O4 quantum dots