Ultrathin Ni_1−xCo_xS₂ nanoflakes as high energy density electrode materials for asymmetric supercapacitors

• Xiaoxiang Wang,
• Teng Wang,
• Rusen Zhou,
• Lijuan Fan,
• Shengli Zhang,
• Feng Yu,
• Tuquabo Tesfamichael,
• Liwei Su and
• Hongxia Wang

Beilstein J. Nanotechnol. 2019, 10, 2207–2216, doi:10.3762/bjnano.10.213

• -dispersive spectrometry (EDS) using an accelerating voltage of 15 kV, and transmission electron microscopy (TEM, JEOL 2100) were used to study the morphology, structure and elemental distributions of the samples. Elemental composition of the as-prepared materials and valence states of each element were

• supported by aluminium SEM sample stages. Chemical composition and valence states of each element in the material are further confirmed by using XPS. The high-resolution XPS spectra confirm the existence of nickel, cobalt, and sulfur. After fitting the XPS with the Gaussian method, the HRXPS spectrum of Ni

Improved adsorption and degradation performance by S-doping of (001)-TiO₂

• Xiao-Yu Sun,
• Xian Zhang,
• Xiao Sun,
• Ni-Xian Qian,
• Min Wang and
• Yong-Qing Ma

Beilstein J. Nanotechnol. 2019, 10, 2116–2127, doi:10.3762/bjnano.10.206

• . Wang et al. reported that TiO2 with an ideal (001) face was inert to both methanol and water, and the activity of the (001) face was only enhanced after surface reduction or reoxidation [11]. It is well known that the conduction band of anatase TiO2 is composed of the Ti 3d state and the valence band

• -S3 sample has the largest ΔR, which is consistent with the XRD results. The XP spectra do not only provide information on the binding energy of the atoms but also on the total density of states (DOS) in the valence band of TiO2 [12][49]. In order to investigate if S-doping produces energy levels

• above the valence band maximum, we measured the valence-band XP spectra of the 2-S0, 2-S0.5, 2-S1, 2-S3 and 2-S5 samples as shown in Figure 5. For all the samples, the valence band maximum is located around 2.4 eV, so S-doping does not shift the valence band maximum towards the forbidden band. Mid-gap

Improvement of the thermoelectric properties of a MoO₃ monolayer through oxygen vacancies

• Wenwen Zheng,
• Wei Cao,
• Ziyu Wang,
• Huixiong Deng,
• Jing Shi and
• Rui Xiong

Beilstein J. Nanotechnol. 2019, 10, 2031–2038, doi:10.3762/bjnano.10.199

• the Γ point, while the maximum of the first valence band (VBM) appears at the S point. The indirect bandgap of the MoO3 monolayer is computed as 1.79 eV for PBE and 2.85 eV for HSE06, which is consistent with previous studies [17][31]. Since the MoO3 monolayer is a wide-gap semiconductor, it is likely

Magnetic properties of biofunctionalized iron oxide nanoparticles as magnetic resonance imaging contrast agents

• Natalia E. Gervits,
• Andrey A. Gippius,
• Alexey V. Tkachev,
• Evgeniy I. Demikhov,
• Sergey S. Starchikov,
• Igor S. Lyubutin,
• Alexander L. Vasiliev,
• Vladimir P. Chekhonin,
• Maxim A. Abakumov,
• Alevtina S. Semkina and
• Alexander G. Mazhuga

Beilstein J. Nanotechnol. 2019, 10, 1964–1972, doi:10.3762/bjnano.10.193

• valence Fe2.5+. At about TV = 120 K the Verwey transition occurs, which leads to changes in the magnetite crystal structure, as well as the electronic and magnetic properties [20]. Below TV the electron exchange between the Fe3+ and Fe2+ ions in the B-sites is frozen. These changes can be easily

• identified in the Mössbauer spectrum of magnetite. Mössbauer spectroscopy is a highly sensitive method with respect to the valence of iron ions in these bulk oxides, since the hyperfine parameters corresponding to Fe3+ and Fe2+ ions are well distinguishable in the spectra. For the processing of the low

First principles modeling of pure black phosphorus devices under pressure

• Ximing Rong,
• Zhizhou Yu,
• Zewen Wu,
• Junjun Li,
• Bin Wang and
• Yin Wang

Beilstein J. Nanotechnol. 2019, 10, 1943–1951, doi:10.3762/bjnano.10.190

• substance of pressure-related quantum transport in pure BP devices in this paper is not changed. When RC = 15%, monolayer BP becomes an indirect bandgap semiconductor. When RC = 30%, the conduction band minimum (CBM) descends below the valence band maximum (VBM), and the monolayer BP finally becomes a

• devices with a length of the pressure region equal to 24L and RC equal to 0 and 15%, respectively. When RC = 0, the Fermi level of both leads locates in the center of conduction-band maximum (CBM) and valence-band maximum (VBM). When RC reaches 15%, both VBM and CBM are pushed towards positive energy

• both zigzag and armchair BP devices, ΔEV is always smaller than ΔEC indicating the valence band domination of quantum transport for all BP devices, especially for the armchair BP devices. More interestingly, ΔEV of the armchair BP devices increases as function of RC when RC is less than 15%, which

Charge-transfer interactions between fullerenes and a mesoporous tetrathiafulvalene-based metal–organic framework

• Manuel Souto,
• Joaquín Calbo,
• Samuel Mañas-Valero,
• Aron Walsh and
• Guillermo Mínguez Espallargas

Beilstein J. Nanotechnol. 2019, 10, 1883–1893, doi:10.3762/bjnano.10.183

• a small bandgap calculated to be 0.90 eV in spin-up or α-channel, and 0.72 eV in spin-down or β-channel (Figure 6), slightly smaller than that predicted for pristine MUV-2 (0.86 eV in β-channel) [53]. Analysis of the projected density of states (PDoS) indicates that the valence band maximum (VBM) in

TiO₂/GO-coated functional separator to suppress polysulfide migration in lithium–sulfur batteries

• Ning Liu,
• Lu Wang,
• Taizhe Tan,
• Yan Zhao and
• Yongguang Zhang

Beilstein J. Nanotechnol. 2019, 10, 1726–1736, doi:10.3762/bjnano.10.168

• Li2S and Li2S2 into the high valence state Li2S4–8 [42][43][44]. One should note that the Li/S batteries with a pristine separator and those with a GO-coated separator exhibit much broader redox peaks than that of the Li/S batteries with TiO2/GO-coated separator due to the high polarization and poor

Giant magnetoresistance ratio in a current-perpendicular-to-plane spin valve based on an inverse Heusler alloy Ti₂NiAl

• Yu Feng,
• Zhou Cui,
• Bo Wu,
• Jianwei Li,
• Hongkuan Yuan and
• Hong Chen

Beilstein J. Nanotechnol. 2019, 10, 1658–1665, doi:10.3762/bjnano.10.161

• utilizing a density functional theory (DFT)-based Vienna ab-initio simulation package (VASP) [31][32]. Ti (3d24s2), Ni (3d84s2), Al (3s23p1) and Ag (4d105s1) were chosen to be the valence electron configurations. The exchange-correlation interaction is described by the Perdew–Burke–Ernzerhof (PBE

Effects of surface charge and boundary slip on time-periodic pressure-driven flow and electrokinetic energy conversion in a nanotube

• Mandula Buren,
• Yongjun Jian,
• Yingchun Zhao,
• Long Chang and
• Quansheng Liu

Beilstein J. Nanotechnol. 2019, 10, 1628–1635, doi:10.3762/bjnano.10.158

• concentration and z is the valence of ions. Taking the Debye–Hückel approximation for low zeta potential, i.e., sinh(ezφ/(kBT)) ≈ ezφ/(kBT), and utilizing Equation 3 and Equation 4 we obtain the linearized Poisson–Boltzmann equation The electric potential distribution φ satisfies where ρe = −εκ2φ is used, ζ is

Kelvin probe force microscopy work function characterization of transition metal oxide crystals under ongoing reduction and oxidation

• Dominik Wrana,
• Karol Cieślik,
• Wojciech Belza,
• Christian Rodenbücher,
• Krzysztof Szot and
• Franciszek Krok

Beilstein J. Nanotechnol. 2019, 10, 1596–1607, doi:10.3762/bjnano.10.155

• and similarities between those two structures. Based on the electronic conduction, most transition metal oxides could be classified as insulators or semiconductors. However, due to the plethora of available valence states in which a cation can be, many transition metal oxides may also exhibit metallic

• also in various heterostructures, with exotic electronic states, e.g., a two-dimensional electron gas (2DEG) on the interface with LaAlO3 [16][17]. On the other side of the transition metal oxides spectrum lies titanium monoxide, TiO, in which the titanium atoms adopt the valence state 2+, contributing

• transformation from (1×1) to (√5×√5)R26.6°, and in the vicinity of extended defects in a crystal (dislocations) which act as easy conduction paths for electrons. Oxygen vacancy formation, and therefore Ti3+ valence, results in the appearance of new t2g electron states within Ti 3d, which are below the conduction

High-temperature resistive gas sensors based on ZnO/SiC nanocomposites

• Vadim B. Platonov,
• Marina N. Rumyantseva,
• Alexander S. Frolov,
• Alexey D. Yapryntsev and
• Alexander M. Gaskov

Beilstein J. Nanotechnol. 2019, 10, 1537–1547, doi:10.3762/bjnano.10.151

• ]. Taking into account the difference in the band gap (Eg) of 2H-SiC (Eg = 3.3 eV [39]) and 3C-SiC (Eg = 2.36 eV [40]) polytypes, and assuming that the position of the valence band for these polytypes does not vary significantly, we constructed a diagram of the band alignment for ZnO and 3C-SiC phases

Rapid thermal annealing for high-quality ITO thin films deposited by radio-frequency magnetron sputtering

• Petronela Prepelita,
• Ionel Stavarache,
• Doina Craciun,
• Florin Garoi,
• Catalin Negrila,
• Beatrice Gabriela Sbarcea and
• Valentin Craciun

Beilstein J. Nanotechnol. 2019, 10, 1511–1522, doi:10.3762/bjnano.10.149

• RTA-treatment in an open atmosphere. The percentage of oxygen pressure used in the experiments is shown in Table 1. It is obvious that the oxygen flux during deposition affects the difference between the maximum valence band and the Fermi level. In this way oxygen-induced acceptor states are formed

• near the valence band (such as oxygen interstitials and indium vacancies) and the number of states increases with increasing oxygen flow. A poor crystalline quality with abundant structural defects leads to effective compensation of doping [33][48]. The metallic nature of the highly conductive ITO

Synthesis of P- and N-doped carbon catalysts for the oxygen reduction reaction via controlled phosphoric acid treatment of folic acid

• Rieko Kobayashi,
• Takafumi Ishii,
• Yasuo Imashiro and
• Jun-ichi Ozaki

Beilstein J. Nanotechnol. 2019, 10, 1497–1510, doi:10.3762/bjnano.10.148

• in N, S, P-doped carbon materials [24]. The 400.5 eV peak observed in the N 1s spectra of the PH-series carbon materials has traditionally been assigned to pyrrole/pyridone-type N. The electron configuration of pyridinic N can be described as follows: Two out of five N valence electrons are used for

• σ-bond formation, two more electrons form an unshared electron pair, and the remaining electron is donated to the π-electron system. Conversely, in the case of pyrrolic N, two valence electrons are used to form C–N–C σ-bonds, one electron is used to form the N–H bond, and the remaining two electrons

BiOCl/TiO₂/diatomite composites with enhanced visible-light photocatalytic activity for the degradation of rhodamine B

• Minlin Ao,
• Kun Liu,
• Xuekun Tang,
• Zishun Li,
• Qian Peng and
• Jing Huang

Beilstein J. Nanotechnol. 2019, 10, 1412–1422, doi:10.3762/bjnano.10.139

• TiO2/diatomite: Therefore, the positions of the valence band (VB) for BiOCl and TiO2/diatomite are 2.64 V and 2.14 V, respectively. The photocatalytic activity is determined not only by the band structure but also by the carrier transport efficiency [47]. In order to study the carrier migration

Construction of a 0D/1D composite based on Au nanoparticles/CuBi₂O₄ microrods for efficient visible-light-driven photocatalytic activity

• Weilong Shi,
• Mingyang Li,
• Hongji Ren,
• Feng Guo,
• Xiliu Huang,
• Yu Shi and
• Yubin Tang

Beilstein J. Nanotechnol. 2019, 10, 1360–1367, doi:10.3762/bjnano.10.134

• novel visible-light-driven photocatalysts. Due to the valence-band hybridization of O 2p and Bi 6s, the bismuth-based photocatalysts possess a relatively narrow bandgap. Moreover, benefiting from the filled Bi 6s band of Bi3+ or the empty 6s band of Bi5+, Bi-containing compounds strongly absorb visible

• suggests that h+ and·O2− are crucial active species during the photocatalysis. Based on the above experimental results, a possible photocatalytic mechanism was proposed (Figure 9). The valence band (VB) and conduction band (CB) positions of CBO can be estimated based on the following equation: where X is

Luminescence of Tb₃Al₅O₁₂ phosphors co-doped with Ce³⁺/Gd³⁺ for white light-emitting diodes

• Yu-Guo Yang,
• Lei Wei,
• Jian-Hua Xu,
• Hua-Jian Yu,
• Yan-Yan Hu,
• Hua-Di Zhang,
• Xu-Ping Wang,
• Bing Liu,
• Cong Zhang and
• Qing-Gang Li

Beilstein J. Nanotechnol. 2019, 10, 1237–1242, doi:10.3762/bjnano.10.123

• increasing x values, which is induced by the substitution of Tb3+ with Ce3+/Gd3+. The ionic radii of Tb3+, Ce3+ and Gd3+ are 1.040 Å (CN = 8), 1.143 Å (CN = 8) and 1.053 Å (CN = 8), respectively. Due to the same valence and similar ionic radii of Tb3+, Ce3+, and Gd3+, Tb3+ ions are replaced by Ce3+ and Gd3

Imaging the surface potential at the steps on the rutile TiO₂(110) surface by Kelvin probe force microscopy

• Masato Miyazaki,
• Huan Fei Wen,
• Quanzhen Zhang,
• Yuuki Adachi,
• Jan Brndiar,
• Ivan Štich,
• Yan Jun Li and
• Yasuhiro Sugawara

Beilstein J. Nanotechnol. 2019, 10, 1228–1236, doi:10.3762/bjnano.10.122

• to the step is localized closely to the top of the valence band compared to a more distant oxygen atom, resulting in decrease of oxygen vacancy formation energy and consequent vacancy migration towards the step. This geometry produces a massive positive charge pinned around a vacancy, see Figure 5c

Quantitative analysis of annealing-induced instabilities of photo-leakage current and negative-bias-illumination-stress in a-InGaZnO thin-film transistors

• Dapeng Wang and
• Mamoru Furuta

Beilstein J. Nanotechnol. 2019, 10, 1125–1130, doi:10.3762/bjnano.10.112

• conduction is insensitive to disorder because the conduction band edge depends on the In s-orbital [1]. However, there is a high density of oxygen-containing trap states (ca. 1020 cm−3) in the region above the valence band [2], which is sensitive to irradiation with light [3]. The typical staggered/coplanar

• the valence band (EV). When the annealing temperature increases to 350 °C, the transfer curves exhibit outstanding initial electrical properties. However, a positive shift accompanied by the appearance of a hump and SS degradation occurs and gradually increases with increasing stress duration. The

Synthesis and characterization of quaternary La(Sr)S–TaS₂ misfit-layered nanotubes

• Marco Serra,
• Erumpukuthickal Ashokkumar Anumol,
• Dalit Stolovas,
• Iddo Pinkas,
• Ernesto Joselevich,
• Reshef Tenne,
• Andrey Enyashin and
• Francis Leonard Deepak

Beilstein J. Nanotechnol. 2019, 10, 1112–1124, doi:10.3762/bjnano.10.111

• treated, applying norm-conserving Troullier–Martins pseudopotentials. The pseudopotential core radii (given in the following in brackets, in aB units) for the valence shells were chosen as 6s2(3.47)6p0(3.74)5d1(3.22) for La, 6s1(2.55)6p0(2.74)5d4(2.55) for Ta, 5s2(3.58)5p0(3.76)4d0(3.58) for Sr, and 3s2

• content. At a Sr content of about 40 atom % the DOS difference with respect to the DOS of pristine LaS–TaS2 MLC becomes more pronounced: a clear shoulder of the valence band appears at −1.0...1.5 eV (see Figure S4, Supporting Information File 1). It consists of S3p-states, which are responsible for the Sr

CuInSe₂ quantum dots grown by molecular beam epitaxy on amorphous SiO₂ surfaces

• Henrique Limborço,
• Pedro M.P. Salomé,
• Rodrigo Ribeiro-Andrade,
• Jennifer P. Teixeira,
• Nicoleta Nicoara,
• Kamal Abderrafi,
• Joaquim P. Leitão,
• Juan C. Gonzalez and
• Sascha Sadewasser

Beilstein J. Nanotechnol. 2019, 10, 1103–1111, doi:10.3762/bjnano.10.110

• energy for the QD [48] and QW [49] can be calculated as: where Eg is the CIS low-temperature bandgap energy, h is the Planck constant, me is the effective conduction-band mass, mh is the effective valence-band mass, e is the rest electron charge, ε is the CIS dielectric constant and Ex is the exciton

Electronic and magnetic properties of doped black phosphorene with concentration dependence

• Ke Wang,
• Hai Wang,
• Min Zhang,
• Yan Liu and
• Wei Zhao

Beilstein J. Nanotechnol. 2019, 10, 993–1001, doi:10.3762/bjnano.10.100

• to 4 × 4, corresponding to an impurity concentration of 1.56%, the direct bandgap of S-doped phosphorene between the conduction band minimum (CBM) and the valence band maximum (VBM) at Γ is opened to 0.32 eV suggesting the S-doped phosphorene becomes a magnetic semiconductor. When the in-plane size

Synthesis of novel C-doped g-C₃N₄ nanosheets coupled with CdIn₂S₄ for enhanced photocatalytic hydrogen evolution

• Jingshuai Chen,
• Chang-Jie Mao,
• Helin Niu and
• Ji-Ming Song

Beilstein J. Nanotechnol. 2019, 10, 912–921, doi:10.3762/bjnano.10.92

• absorption coefficient, h being Planck’s constant, and v being the frequency. The Eg of g-C3N4, CCN and CdIn2S4 are estimated as 2.82 eV, 2.79 eV and 2.26 eV, respectively. Besides, the position of the valence band is determined by the following equation: EVB = X − Ec − 0.5Eg, where Ec is the energy of free

• electrons on the hydrogen scale (about 4.5 eV), X is the electronegativity of the semiconductor, and Eg is the band gap energy of the semiconductor. The edge of the valence band (VB) and conduction band (CB) of g-C3N4, CCN and CdIn2S4 are summarized in Table 1. The separation–recombination rate of photo

• position of the conduction and valence bands of the g-C3N4 and CCN samples. CCN has a narrower band gap than the original g-C3N4 because of the C-doping, allowing for more visible light to be harvested. Furthermore, C-doping can increase the π-electron availability and reduce the hydrogen absorption energy

Comparing a porphyrin- and a coumarin-based dye adsorbed on NiO(001)

• Sara Freund,
• Antoine Hinaut,
• Nathalie Marinakis,
• Edwin C. Constable,
• Ernst Meyer,
• Catherine E. Housecroft and
• Thilo Glatzel

Beilstein J. Nanotechnol. 2019, 10, 874–881, doi:10.3762/bjnano.10.88

• first step towards the design of tandem solar cells with two photoactive electrodes [17][18]. In p-type DSSCs, the charge transfer is in the opposite direction to that in n-type devices. Holes are injected from the highest occupied molecular orbital (HOMO) of the dye to the valence band (VB) of the

Electronic properties of several two dimensional halides from ab initio calculations

• Mohamed Barhoumi,
• Ali Abboud,
• Lamjed Debbichi,
• Moncef Said,
• Torbjörn Björkman,
• Dario Rocca and
• Sébastien Lebègue

Beilstein J. Nanotechnol. 2019, 10, 823–832, doi:10.3762/bjnano.10.82

• to the top of the valence bands. For instance, for AcOBr, the top of the valence bands is made of states coming from Ac, O, and Br, while Ac-derived states constitute most of the bottom of the conduction bands, as seen in the corresponding PDOS. Similarly, we have computed the DOSs and PDOSs of XOCl

• (where X = Cr, Ga, In, La) monolayers, as presented in Figure 4. For instance, we can see from the PDOS of AcOCl that the valence bands come from the Ac, O, and Cl atoms while the bottom of the conduction bands correspond mainly to states derived from the Ac atoms. The DOSs and PDOSs of the fluoride

• monolayers CrOF, GaOF, InOF and LaOF are shown in Figure 5. From the DOS, it can be seen that the CrOF monolayer has a finite spin polarisation, and its magnetic moments are ordered ferromagnetically. Also, it is seen that the fluorine atoms contribute to the valence bands for all fluorides monolayers, while

Tungsten disulfide-based nanocomposites for photothermal therapy

• Tzuriel Levin,
• Hagit Sade,
• Rina Ben-Shabbat Binyamini,
• Maayan Pour,
• Iftach Nachman and
• Jean-Paul Lellouche

Beilstein J. Nanotechnol. 2019, 10, 811–822, doi:10.3762/bjnano.10.81

• chemistry, thanks to an available valence electron in its 4f orbital. In our group, cerium was utilized in the complex form of ceric ammonium nitrate [(NH4)2Ce(IV)(NO3)6, or CAN]. In CAN the cerium ion is coordinated with six nitrate ligands through their oxygen atoms. CAN is a strong oxidizer, turning