TiO_x/Pt₃Ti(111) surface-directed formation of electronically responsive supramolecular assemblies of tungsten oxide clusters

• Marco Moors,
• Yun An,
• Agnieszka Kuc and
• Kirill Yu. Monakhov

Beilstein J. Nanotechnol. 2021, 12, 203–212, doi:10.3762/bjnano.12.16

• electronic properties were obtained by employing PBE exchange–correlation functional [32] with the D3(BJ) dispersion correction [33][34][35], the valence triple-zeta polarized (TZP) basis sets composed of Slater-type and numerical orbitals, and scalar zero-order regular approximation (ZORA) [36]. STM images

ZnO and MXenes as electrode materials for supercapacitor devices

• Ameen Uddin Ammar,
• Ipek Deniz Yildirim,
• Feray Bakan and
• Emre Erdem

Beilstein J. Nanotechnol. 2021, 12, 49–57, doi:10.3762/bjnano.12.4

• in semiconductors is fundamentally the same, regardless of composition. Defects generate bandgap states that either generate electrons in the conduction band or holes in the valence band. Therefore, we believe that the discussion, based on experimental results, of the magnitude of this effect for 2D

Free and partially encapsulated manganese ferrite nanoparticles in multiwall carbon nanotubes

• Saja Al-Khabouri,
• Salim Al-Harthi,
• Toru Maekawa,
• Mohamed E. Elzain,
• Ashraf Al-Hinai,
• Ahmed D. Al-Rawas,
• Abbsher M. Gismelseed,
• Ali A. Yousif and
• Myo Tay Zar Myint

Beilstein J. Nanotechnol. 2020, 11, 1891–1904, doi:10.3762/bjnano.11.170

• are the first UPS measurements carried out for this system. Figure 1e provides the structure of the valence band of free MnFe2O4 nanoparticles. Experimental results indicate that the density of states (DOS) at the Fermi level, EF (i.e., at a zero binding energy in the UPS spectrum) is consistent with

• that of half-metallic behavior (Figure 1e, inset). Ideally, stoichiometric MnFe2O4 is predicted to be a half metal with a low carrier density [17]. A valence band maximum of 0.85 eV, derived from the spectrum, is in line with its predicted half-metallic behavior. However, it is to be noted that

• semiconducting structures [31][32]. The valence edge of the CNTs correspond to the work function [33]. The well-known features of three-fold coordination of C atoms are the deep-lying σ band, corresponding to a strong in-plane bonding located at 8.1 eV, and delocalized π bands, representing the weak bonding

Kondo effects in small-bandgap carbon nanotube quantum dots

• Patryk Florków,
• Damian Krychowski and
• Stanisław Lipiński

Beilstein J. Nanotechnol. 2020, 11, 1873–1890, doi:10.3762/bjnano.11.169

• dots (CNTQDs) is an extended two-orbital Anderson model: where the dot Hamilonian reads: with site dot energies: depending on the magnetic field B∥ and the gate voltage Vg. The upper and lower signs, ±, refer to conduction or valence states, μo is orbital magnetic moment μo = evFD/4, where vF is the

Unravelling the interfacial interaction in mesoporous SiO₂@nickel phyllosilicate/TiO₂ core–shell nanostructures for photocatalytic activity

• Bridget K. Mutuma,
• Xiluva Mathebula,
• Isaac Nongwe,
• Bonakele P. Mtolo,
• Boitumelo J. Matsoso,
• Rudolph Erasmus,
• Zikhona Tetana and
• Neil J. Coville

Beilstein J. Nanotechnol. 2020, 11, 1834–1846, doi:10.3762/bjnano.11.165

• brookite phases, the anatase phase has been extensively used for photocatalysis owing to its enhanced surface properties [7][8][9][10]. In a typical photocatalytic process, photons of energy greater than the bandgap energy of TiO2 excite electrons to the conduction band leaving holes in the valence band

• displayed good stability and reusability for the degradation of dye molecules and wastewater treatment. Figure 6 shows a possible mechanism for the photoactivity of mSiO2@NiPS and mSiO2@NiPS/TiO2. Upon light irradiation, electrons are excited from the valence band of both materials to the conduction band

• while holes are created in the valence band allowing for the separation of electrons and holes (Figure 6a). The electrons in the conduction band can react with oxygen to form reactive superoxide radicals, which oxidize the MV dye molecules [70]. Also, the holes in the valence band react with H2O to

Absorption and photoconductivity spectra of amorphous multilayer structures

• Oxana Iaseniuc and
• Mihail Iovu

Beilstein J. Nanotechnol. 2020, 11, 1757–1763, doi:10.3762/bjnano.11.158

• with m = 2 is explained by the existence of an exponential distribution of the localized sates in the bandgap of the amorphous material. In this case the I–V characteristics are described by the expression [15]: where j is the current density, Nv is the effective density of states in the valence band

The influence of an interfacial hBN layer on the fluorescence of an organic molecule

• Christine Brülke,
• Oliver Bauer and
• Moritz M. Sokolowski

Beilstein J. Nanotechnol. 2020, 11, 1663–1684, doi:10.3762/bjnano.11.149

• states and the dynamical CT in the excited state can be probed by photoemission spectroscopy (PES). In particular, core hole clock spectroscopy has been used to measure the time constant of dynamical CT in the valence band states as a function of the lifetime of the core hole, which is typically of the

• a disordered phase, while the RT state forms highly ordered domains [44]. This is accompanied by a change in the valence band structure as seen, for example, in UPS [44]. Thus, instead of a multilayer/monolayer effect, the above described differences in the Raman shifts may also be caused by the

Controlling the electronic and physical coupling on dielectric thin films

• Philipp Hurdax,
• Michael Hollerer,
• Larissa Egger,
• Georg Koller,
• Xiaosheng Yang,
• Anja Haags,
• Serguei Soubatch,
• Frank Stefan Tautz,
• Mathias Richter,
• Alexander Gottwald,
• Peter Puschnig,
• Martin Sterrer and
• Michael G. Ramsey

Beilstein J. Nanotechnol. 2020, 11, 1492–1503, doi:10.3762/bjnano.11.132

• molecules on the surface. The images of orbitals of molecules adsorbed on surfaces can also be obtained from the angular intensity distribution in valence band photoemission experiments via PT [27]. When the photoelectron emission angle is converted to momentum, the resulting momentum maps approximately

• to the same saturation exposure on the same 2 ML MgO(100) film. The initial work function, ΦMgO, was tuned to different values. Figure 4a shows wide scans in normal emission, where the MgO valence band dominates at an energy between 9 and 4 eV below EF. For ΦMgO greater than 2.8 eV, there is only a

• ][34] produces a scatter of the ΦMgO values on either side of the critical work function (Φcrit = 2.8 eV). Figure 5 shows the evolution of the ARUPS spectra with an increasing 6P dose on an MgO(100) film with ΦMgO = 2.58 eV (i.e., below Φcrit). In the MgO valence band region (Figure 5a), gradual

Antimicrobial metal-based nanoparticles: a review on their synthesis, types and antimicrobial action

• Matías Guerrero Correa,
• Fernanda B. Martínez,
• Cristian Patiño Vidal,
• Camilo Streitt,
• Juan Escrig and
• Carol Lopez de Dicastillo

Beilstein J. Nanotechnol. 2020, 11, 1450–1469, doi:10.3762/bjnano.11.129

• from light irradiation to excite and mobilize an electron from the valence band to the conduction band, leaving a highly reactive gap (H+). This zone becomes a ROS source as it interacts with H2O or OH− that surrounds the nanoparticles [152]. In addition to molecules such as ascorbic acid, carotene

Impact of fluorination on interface energetics and growth of pentacene on Ag(111)

• Qi Wang,
• Meng-Ting Chen,
• Antoni Franco-Cañellas,
• Bin Shen,
• Thomas Geiger,
• Holger F. Bettinger,
• Frank Schreiber,
• Ingo Salzmann,
• Alexander Gerlach and
• Steffen Duhm

Beilstein J. Nanotechnol. 2020, 11, 1361–1370, doi:10.3762/bjnano.11.120

• of chemisorption [74][75][76][77], pointed to a weak interfacial coupling. Figure 2a shows the UPS data for the valence band region of stepwise deposited F4PEN on Ag(111). For a nominal thickness of 1 Å, two peaks that could be assigned to the HOMO and HOMO−1 levels of F4PEN were visible. The low BE

•  2a). However, the HOMO-derived peak broadened, and for a nominal thickness of 48 Å, its onset was at 1.51 eV BE. The HOMO−1-derived peak also broadened, but its maximum showed a shift to higher BE with increasing coverage. This shift was essentially parallel to that of a deeper-lying valence electron

• , the valence band spectra were almost identical for the monolayer coverages. In all cases, the HOMO-derived peak was centered at 1.85 eV, while the peak centered at a higher BE (≈3.00 eV) was identified as the HOMO−1-derived peak. In addition, the vertical adsorption geometries were rather similar

Structural and electronic properties of SnO₂ doped with non-metal elements

• Jianyuan Yu,
• Yingeng Wang,
• Yan Huang,
• Xiuwen Wang,
• Jing Guo,
• Jingkai Yang and
• Hongli Zhao

Beilstein J. Nanotechnol. 2020, 11, 1321–1328, doi:10.3762/bjnano.11.116

• CASTEP program based on DFT. The Perdew–Burke–Ernzerhof (PBE) generalized gradient approximation (GGA) was selected as the exchange–correlation functional. The interaction between inner electrons and valence electrons was described by the OTFG ultra-soft pseudopotential. The valence electronic

• conduction band. The electronic structure including the energy band structure, total density of states and partial wave state density of the doped system are shown in Figure 2. For SnO2, the Fermi energy level is at the top of the valence band, indicating that the conductivity of SnO2 is low. The conduction

• band minimum (CBM) and the valence band maximum (VBM) are located at the same G point, which is consistent with the calculation results [14][15] indicating that SnO2 is a direct bandgap semiconductor. In this work, the calculated bandgap is 1.28 eV, which is consistent with previous calculation results

Influence of the magnetic nanoparticle coating on the magnetic relaxation time

• Mihaela Osaci and
• Matteo Cacciola

Beilstein J. Nanotechnol. 2020, 11, 1207–1216, doi:10.3762/bjnano.11.105

• surface potential of the i-th nanoparticle at infinite separation, z is the ion valence, e = 1.6 × 10−19 C and k is the thickness of the screening ionic layer “κ”, estimated by the inverse of Debye constant. Polymers and surfactants are usually used for steric stabilization. The model uses the following

Hybridization vs decoupling: influence of an h-BN interlayer on the physical properties of a lander-type molecule on Ni(111)

• Maximilian Schaal,
• Takumi Aihara,
• Marco Gruenewald,
• Felix Otto,
• Jari Domke,
• Roman Forker,
• Hiroyuki Yoshida and
• Torsten Fritz

Beilstein J. Nanotechnol. 2020, 11, 1168–1177, doi:10.3762/bjnano.11.101

• -temperature scanning tunneling microscopy. Finally, the investigation of the valence band structure by ultraviolet photoelectron spectroscopy shows that the low work function of h-BN/Ni(111) further decreases after the DBP deposition. For this reason, the h-BN-passivated Ni(111) surface may serve as potential

• as clusters of molecules on top of the first DBP layer. The fast Fourier transform (FFT) of that STM image resembles the LEED simulation of the molecular lattice (considering eight symmetry equivalent domains only), which supports our structural model. Valence band structure and work function change

• is consistent with vacuum level alignment (see section “Valence band structure and work function change” above). The origin of the more pronounced broadening as well as the asymmetric line shape [45] of the C 1s level in the case of DBP on bare Ni(111) may stem from a variety of different adsorption

Monolayers of MoS₂ on Ag(111) as decoupling layers for organic molecules: resolution of electronic and vibronic states of TCNQ

• Asieh Yousofnejad,
• Gaël Reecht,
• Nils Krane,
• Christian Lotze and
• Katharina J. Franke

Beilstein J. Nanotechnol. 2020, 11, 1062–1071, doi:10.3762/bjnano.11.91

• due to the rapid decay of the tunneling constant with k∥[38][45]. The same applies to the valence band maximum, such that the strongest feature in the tunneling spectra at −2 V arises from bands close to the point [38]. Comparison of spectra on the moiré hollow sites suggest a rigid shift of the

• . The reduced spatial resolution is most probably caused by the overlap with density of states of the substrate as we are approaching the onset of the valence band of MoS2. One may suggest that the stronger localization of dI/dV intensity toward the quinone center is in agreement with the large

• considerations may help when searching for appropriate decoupling layers for specific molecules. We have challenged the decoupling properties of MoS2/Ag(111) for TCNQ molecules. These exhibit their LUMO resonance just at the conduction band onset of MoS2, whereas the HOMO lies within the valence band. Hence, the

Excitonic and electronic transitions in Me–Sb₂Se₃ structures

• Nicolae N. Syrbu,
• Victor V. Zalamai,
• Ivan G. Stamov and
• Stepan I. Beril

Beilstein J. Nanotechnol. 2020, 11, 1045–1053, doi:10.3762/bjnano.11.89

• the electrons at the bottom of the conduction band (mc* = 0.67m0) as well as the holes at the four top valence bands (mv1* = 3.32m0, mv2* = 3.83m0, mv3* = 3.23m0 and mv4* = 3.23m0) were calculated in the Г-point of the Brillouin zone. The magnitude of the valence band splitting V1–V2 due to the spin

• absorption, reflection and excitonic spectra were obtained. The Sb2Se3 crystalline anisotropy of the ground and excited states of four excitonic series were determined at 300 and 11 K. Due to the crystal field (Δcf) and spin–orbit (Δso) interactions, the high valence band splittings were estimated in the

• single crystals was carried out by our group [24]. Since Sb2S3 and Sb2Se3 have a similar band structure, the four excitonic states (A, B, C and D) were also obtained for the Sb2S3 single crystals. Based in our previous work [24], the exciton binding energies, valence band parameters, valence band

Electrochemical nanostructuring of (111) oriented GaAs crystals: from porous structures to nanowires

• Elena I. Monaico,
• Eduard V. Monaico,
• Veaceslav V. Ursaki,
• Shashank Honnali,
• Vitalie Postolache,
• Karin Leistner,
• Kornelius Nielsch and
• Ion M. Tiginyanu

Beilstein J. Nanotechnol. 2020, 11, 966–975, doi:10.3762/bjnano.11.81

• band at 1.485 eV is related to the recombination of electrons from the conduction band with holes trapped by the SiAs state the energy level of which is situated 35 meV above the valence band [31]. The higher intensity of the emission from the anodized GaAs sample is indicative of an effective

Effect of Ag loading position on the photocatalytic performance of TiO₂ nanocolumn arrays

• Jinghan Xu,
• Yanqi Liu and
• Yan Zhao

Beilstein J. Nanotechnol. 2020, 11, 717–728, doi:10.3762/bjnano.11.59

• structures were observed using a field emission scanning electron microscope (FE-SEM, FEI, Tecnai G2 F30). The elemental composition and valence distribution of the film were measured by X-ray photoelectron spectroscopy (XPS, Thermo Fisher Scientific, ESCALAB 250Xi). The photoluminescence (PL) intensity of

• the sample. Meanwhile, the two characteristic peaks of Ti 2p are located at 458.6 and 464.3 eV in Figure 5c. These peaks represent the binding energy of Ti 2p3/2 and Ti 2p1/2, which indicates that Ti is in the +4 valence state in the sample. The spacing between the two peaks of 5.7 eV is also

• , transfer to the conduction band of TiO2, or directly participate in the catalytic reaction [39]. Because of the wide bandgap, TiO2 can only absorb UV light. After the valence band electron absorbs the photon energy, it transitions from the valence band to the conduction band, and it takes part in the

Preparation, characterization and photocatalytic performance of heterostructured CuO–ZnO-loaded composite nanofiber membranes

• Wei Fang,
• Liang Yu and
• Lan Xu

Beilstein J. Nanotechnol. 2020, 11, 631–650, doi:10.3762/bjnano.11.50

• -loaded CNFMs is illustrated in Figure 24. When the UV light irradiates the CuO-ZnO heterostructure on the CNFMs, the valence-band (VB) electrons are excited to the conduction band (CB), resulting in the formation of electron–hole pairs. Holes and electrons both act in the photocatalytic degradation of

Multilayer capsules made of weak polyelectrolytes: a review on the preparation, functionalization and applications in drug delivery

• Varsha Sharma and
• Anandhakumar Sundaramurthy

Beilstein J. Nanotechnol. 2020, 11, 508–532, doi:10.3762/bjnano.11.41

• the film erosion rate, the effect of ionic strength was largely dependent on the type and valence state of the salts [51]. Although the hydrogen bond is much weaker than the electrostatic interactions, and could be easily damaged by the dissolution processes, their stimuli responsiveness and the

Evolution of Ag nanostructures created from thin films: UV–vis absorption and its theoretical predictions

• Robert Kozioł,
• Marcin Łapiński,
• Paweł Syty,
• Damian Koszelow,
• Wojciech Sadowski,
• Józef E. Sienkiewicz and
• Barbara Kościelska

Beilstein J. Nanotechnol. 2020, 11, 494–507, doi:10.3762/bjnano.11.40

• Evolution 220 spectrophotometer in transmission mode, in a range of 200–1100 nm. For these measurements films were deposited on glass substrates. The quality of the obtained nanostructures and the valence states of Ag were measured using X-ray photoelectron spectroscopy (XPS, Omicron NanoTechnology

• the spectrum corresponding to the 3 nm layer, an additional maximum appears at about 350 nm, which is also present in the spectra of thicker samples. In metals, valence and conduction bands can overlap, which leads to a continuous spectrum of sites available for electrons. However, for inner levels

• observed using XPS. The spectral contribution of 5s and 5p electronic states to the valence band spectrum of Ag is negligible and the valence band mainly originates from 4d electronic state. The Ag 3d valence-band and Ag 4d core-level spectra are shown, respectively, in Figure 12a and Figure 12b. It should

Interfacial charge transfer processes in 2D and 3D semiconducting hybrid perovskites: azobenzene as photoswitchable ligand

• Nicole Fillafer,
• Tobias Seewald,
• Lukas Schmidt-Mende and
• Sebastian Polarz

Beilstein J. Nanotechnol. 2020, 11, 466–479, doi:10.3762/bjnano.11.38

• states of naphthalene [23]. Regarding the electronic alignment of molecular orbitals, valence and conduction bands, the chromophore may serve as a quantum well [24]. The energy transfer between the semiconducting perovskite layer and the chromophore can easily be influenced by the chemical structure and

• photoswitching of azobenzene on semiconducting TiO2 is suppressed due to a sudden oxidation of the chromophore. The formation of a heterogeneous charge-transfer complex disturbs the isomerisation and no photoswitching is observed [37]. To clarify possible electronical processes, the relative energies of valence

Synthesis and enhanced photocatalytic performance of 0D/2D CuO/tourmaline composite photocatalysts

• Changqiang Yu,
• Min Wen,
• Zhen Tong,
• Shuhua Li,
• Yanhong Yin,
• Xianbin Liu,
• Yesheng Li,
• Tongxiang Liang,
• Ziping Wu and
• Dionysios D. Dionysiou

Beilstein J. Nanotechnol. 2020, 11, 407–416, doi:10.3762/bjnano.11.31

• nontoxic products. In this work, a CuO/tourmaline composite with zero-dimensional/two-dimensional (0D/2D) CuO architecture was successfully obtained via a facile hydrothermal process, and its photocatalytic activity was evaluated by the degradation of methylene blue (MB). Surface element valence state and

• ), (410), (122), (051), (232), (511), (502), (431), (303), (152), (342), (143), (063), (271), (550), (054), (713), and (505) planes of schorl (JCPDS 85-1811). No impurity peaks were detected, indicating the predominance of CuO and tourmaline in the composite. The surface element component and valence

• −. With a combination of the analyses carried out above, a plausible mechanism for strengthening the photocatalytic degradation activity of CuO with tourmaline was proposed and shown in Figure 9. The e− in the valence band (VB) of CuO was excited with the generation of e−/h+ pairs under light irradiation

DFT calculations of the structure and stability of copper clusters on MoS₂

• Cara-Lena Nies and
• Michael Nolan

Beilstein J. Nanotechnol. 2020, 11, 391–406, doi:10.3762/bjnano.11.30

• functional [35]. The valence electrons are described explicitly using a plane wave basis set with an energy cut-off of 450 eV. The valence electron configurations used for this study are Mo = 5s14d5, S = 3s23p4 and Cu = 4s13d10. The core–valence electron interactions are described using the projector

High-performance asymmetric supercapacitor made of NiMoO₄ nanorods@Co₃O₄ on a cellulose-based carbon aerogel

• Meixia Wang,
• Jing Zhang,
• Xibin Yi,
• Benxue Liu,
• Xinfu Zhao and
• Xiaochan Liu

Beilstein J. Nanotechnol. 2020, 11, 240–251, doi:10.3762/bjnano.11.18

• , which agrees well with the XRD results. To investigate the chemical composition and the valence states of the NiMoO4@Co3O4/CA nanocomposite, X-ray photoelectron spectroscopy (XPS) was performed and the results are shown in Figure 4. According to Figure 4a, the elements Co, Ni, Mo, O and C can be clearly

Nonequilibrium Kondo effect in a graphene-coupled quantum dot in the presence of a magnetic field

• Levente Máthé and
• Ioan Grosu

Beilstein J. Nanotechnol. 2020, 11, 225–239, doi:10.3762/bjnano.11.17

• [52]. The points where the conduction and valence bands touch each other in momentum space are the Dirac points. The Dirac points play an important role in the electronic properties of graphene because around these points low-energy excitations can be achieved. Furthermore, the motion of the charge

• Keldysh nonequilibrium Green’s function theory by Li and co-workers [67]. They found that the Kondo peak can be observed in a wide parameter range from the Kondo regime to the mixed valence regime or to the empty orbital regime, which is in agreement with the literature [68][69][70]. In the latter two