Reduced graphene oxide supported C₃N₄ nanoflakes and quantum dots as metal-free catalysts for visible light assisted CO₂ reduction

• Md Rakibuddin and
• Haekyoung Kim

Beilstein J. Nanotechnol. 2019, 10, 448–458, doi:10.3762/bjnano.10.44

• , we report the synthesis of novel reduced graphene oxide (rGO)-supported C3N4 nanoflake (NF) and quantum dot (QD) hybrid materials (GCN) for visible light induced reduction of CO2. The C3N4 NFs and QDs are prepared by acid treatment of C3N4 nanosheets followed by ultrasonication and hydrothermal

• , and 20 h) to yield g-C3N4 NFs and QDs. The product obtained after 5 h of heating at 190 °C is denoted as CN-5, and those obtained after 10 and 20 h heating at 130 °C are denoted as CN-10 and CN-20, respectively. Preparation of rGO@g-C3N4 nanoflake/quantum dot hybrid materials (GCN) GO was synthesized

• dots. Particle size distribution of the synthesized CN nanoflakes and quantum dots. TEM image of CN nanoflake and quantum dot samples under heating at 190 °C for 5 h (a,b), 170 °C for 5 h (c,d), and 150 °C for 5 h (e,f). Field emission scanning electron microscopy images of the a) g-C3N4 nanosheet, b

Transport signatures of an Andreev molecule in a quantum dot–superconductor–quantum dot setup

• Zoltán Scherübl,
• András Pályi and
• Szabolcs Csonka

Beilstein J. Nanotechnol. 2019, 10, 363–378, doi:10.3762/bjnano.10.36

• experiments and applications. Keywords: Andreev bound state; crossed Andreev reflection; elastic co-tunneling; quantum dot; Introduction Superconducting hybrid nanodevices provide a promising platform for quantum architectures. While superconductors (SCs) allow for a spatially extended coherent state

• . Finally, we analyze the transport signatures of the different non-local coupling terms via the zero bias conductance, the finite-bias conductance, and the triplet blockade effect. Model Microscopic Hamiltonian of the proximitized double quantum dot Throughout this work, we study a standard Cooper-pair

• tunneling to the N leads is assumed to be weak, and are treated by Fermi’s Golden Rule in the transport model outlined below. Finally, describes interdot tunneling (IT), i.e., direct tunneling between the QDs, with an amplitude tLR. Effective Hamiltonian of the proximitized double quantum dot The complete

Time-resolved universal temperature measurements using NaYF₄:Er³⁺,Yb³⁺ upconverting nanoparticles in an electrospray jet

• Kristina Shrestha,
• Arwa A. Alaulamie,
• Ali Rafiei Miandashti and
• Hugh H. Richardson

Beilstein J. Nanotechnol. 2018, 9, 2916–2924, doi:10.3762/bjnano.9.270

• ][18][19][20][21][22][23][24][25][26][27], phase transitions [28][29], quantum dot luminescence thermometry [30], and ultrafast pump–probe measurements [31][32][33][34]. An optical temperature measurement has the advantage of remote sensing but is diffraction-limited with the spatial uncertainty

Variation of the photoluminescence spectrum of InAs/GaAs heterostructures grown by ion-beam deposition

• Alexander S. Pashchenko,
• Leonid S. Lunin,
• Eleonora M. Danilina and
• Sergei N. Chebotarev

Beilstein J. Nanotechnol. 2018, 9, 2794–2801, doi:10.3762/bjnano.9.261

• . It is shown that isovalent doping of GaAs potential barriers by bismuth was accompanied by a red-shift of the photoluminescence peak of InAs quantum dots of 121 meV. Keywords: infrared photodetectors; ion-beam deposition; nanoheterostructures; photoluminescence; quantum dot; semiconductors

• photodetectors (QWIPs) [4]. The QWIPs, in turn, have a simpler technology but a low quantum efficiency and require cooling. One way to solve these problems is to grow semiconductor heterostructures in which QDs are embedded. The localization of photogenerated charge carriers in a quantum dot along three

• : the top with a GaAs strain-reducing layer; the bottom with a strained buffer layer (wetting layer) [15][16][17][18][19]. Thus, the simplified energy band diagram of the active region of an InAs/GaAs heterostructure is an InAs quantum dot built into a GaAs matrix in the form of a quantum well. It

Two-dimensional semiconductors pave the way towards dopant-based quantum computing

• José Carlos Abadillo-Uriel,
• Belita Koiller and
• María José Calderón

Beilstein J. Nanotechnol. 2018, 9, 2668–2673, doi:10.3762/bjnano.9.249

• oscillations [11]. This problem can be deterrent to the implementation of quantum computing in Si due to the relative lack of control about the exact position of dopants in the bulk. Alternative proposals suggested to overcome this difficulty include hybrid dopant–quantum dot structures [12][13], a charge–spin

Interaction-induced zero-energy pinning and quantum dot formation in Majorana nanowires

• Samuel D. Escribano,
• Alfredo Levy Yeyati and
• Elsa Prada

Beilstein J. Nanotechnol. 2018, 9, 2171–2180, doi:10.3762/bjnano.9.203

• -dimensional model of the dielectric surroundings, here we show that, under certain circumstances, these interactions lead to a suppression of the Majorana oscillations predicted by simpler theoretical models, and to the formation of low-energy quantum-dot states that interact with the Majorana modes. Both

• unexplored before is the creation of deep potential wells at the ends of the wire close to the bulk metallic electrodes. These wells, obtained explicitly here through the self-consistent calculation, are similar to the confinement potentials typical of quantum dots. Localized quantum dot-like energy levels

• . In the next section we study the effect of including the bulk normal leads of Figure 1a, finding that they give rise to the formation of quantum dot-like bound states. We further analyze the interplay of such states with the MBSs. Finally, we present the conclusions of our work. The robustness of the

Cryochemical synthesis of ultrasmall, highly crystalline, nanostructured metal oxides and salts

• Elena A. Trusova and
• Nikolai S. Trutnev

Beilstein J. Nanotechnol. 2018, 9, 1755–1763, doi:10.3762/bjnano.9.166

• dispersity by 3–18 times and to increase their specific surface area by an order of magnitude. The proposed approach also reduces the agglomeration of the nanoparticles, and at the same time, results in NiO, Fe2O3 and CeO2 crystallite sizes of less than 10 nm (quantum dot size regime). The diameter of NaNO3

A zero-dimensional topologically nontrivial state in a superconducting quantum dot

• Pasquale Marra,
• Alessandro Braggio and
• Roberta Citro

Beilstein J. Nanotechnol. 2018, 9, 1705–1714, doi:10.3762/bjnano.9.162

• spectrum. Here, we show that a quantum dot coupled with two superconducting leads can realize a nontrivial zero-dimensional topological superconductor with broken time-reversal symmetry, which corresponds to the finite size limit of the one-dimensional topological superconductor. Topological phase

• simplest realization of such a 0D topological superconductor, i.e., a quantum dot [51][52][53][54] coupled with two superconducting leads in a magnetic Zeeman field, forming a superconductor–quantum dot–superconductor (SC–QD–SC) Josephson junction. Zero-energy modes and the corresponding CPR

• consider a semiconducting quantum dot in a magnetic field B and coupled with two superconducting leads, as shown in Figure 1. We assume that the only effect of the magnetic field is the lifting of the spin degeneracy via the Zeeman effect, and we neglect orbital effects of the field. Moreover, we assume

Josephson effect in junctions of conventional and topological superconductors

• Alex Zazunov,
• Albert Iks,
• Miguel Alvarado,
• Alfredo Levy Yeyati and
• Reinhold Egger

Beilstein J. Nanotechnol. 2018, 9, 1659–1676, doi:10.3762/bjnano.9.158

• spinful TS nanowire model can generate a Josephson effect. The critical current is much smaller in the topological regime and exhibits a kink-like dependence on the Zeeman field along the wire. When a correlated quantum dot (QD) in the magnetic regime is present in the junction region, however, the

• magnetic impurity in a local magnetic field. We here analyze the S–QD–TS setup in Figure 1a in some detail, where a quantum dot (QD) is present within the S–TS junction region. The QD is modeled as an Anderson impurity [36], which is equivalent to a spin-1/2 quantum impurity over a wide parameter regime

• that similar ideas have also been explored for TS–N–TS systems [55]. Results and Discussion S–QD–TS junction Model Let us start with the case of an S–QD–TS junction, where an interacting spin-degenerate single-level quantum dot (QD) is sandwiched between a conventional s-wave superconductor (S) and a

Spatial Rabi oscillations between Majorana bound states and quantum dots

• Jun-Hui Zheng,
• Dao-Xin Yao and
• Zhi Wang

Beilstein J. Nanotechnol. 2018, 9, 1527–1535, doi:10.3762/bjnano.9.143

• of this amplitude equality by analyzing the spatial Rabi oscillations of the quantum states of a quantum dot that is tunneling-coupled to the Majorana bound states. Results: We find two resonant Rabi driving energies that correspond to the energy splitting due to the coupling of two spatially

• separated Majorana bound states. The resulting Rabi oscillating frequencies from these two different resonant driving energies are identical for the Majorana bound states, while different for ordinary Andreev bound states. We further study a double-quantum-dot setup and find a nonlocal quantum correlation

• splitting between two Majorana bound states. Keywords: Andreev bound state; Majorana bound state; nonlocal quantum correlation; quantum dot; spatial Rabi oscillation; Introduction Majorana bound states are exotic non-Abelian quasiparticles in topological superconductors [1][2][3][4][5][6][7][8][9][10][11

Colorimetric detection of Cu²⁺ based on the formation of peptide–copper complexes on silver nanoparticle surfaces

• Gajanan Sampatrao Ghodake,
• Surendra Krishna Shinde,
• Rijuta Ganesh Saratale,
• Avinash Ashok Kadam,
• Ganesh Dattatraya Saratale,
• Asad Syed,
• Fuad Ameen and
• Dae-Young Kim

Beilstein J. Nanotechnol. 2018, 9, 1414–1422, doi:10.3762/bjnano.9.134

• . Although colorimetric probes based on the aggregation of nanoparticles (NPs) induced by target-metal ions are advantageous, these probes may have difficulties in detecting Cu2+ in complex matrices [7]. Quantum-dot-based fluorescent probes showed improved sensitivity and selectivity for Cu2+ compared to

Interplay between pairing and correlations in spin-polarized bound states

• Szczepan Głodzik,
• Aksel Kobiałka,
• Anna Gorczyca-Goraj,
• Andrzej Ptok,
• Grzegorz Górski,
• Maciej M. Maśka and
• Tadeusz Domański

Beilstein J. Nanotechnol. 2018, 9, 1370–1380, doi:10.3762/bjnano.9.129

• square lattice of a superconducting host, (ii) a nanoscopic chain of magnetic impurities on the classical superconductor (i.e., proximitized Rashba nanowire) in its topologically trivial/nontrivial superconducting phase, and (iii) a strongly correlated quantum dot side-attached to the Rashba chain, where

• attempting to braid the Majorana end modes, e.g., in T-shape nanowires upon turning on and off the topological superconducting phase in its segments. We briefly analyse here the polarized zero-energy Majorana modes leaking into the multi-site quantum dot (comprising ten lattice sites) side-attached to the

• proximitized Rashba chain discussed above. Figure 6 displays the spatial profile of the polarized spectrum obtained at ω = 0 as a function of the gate voltage Vg, which detunes the energies Vg = εi − μ of the multi-site (1 ≤ i ≤ 10) quantum dot. For numerical calculations we used the model parameters λ = 0.15t

Disorder-induced suppression of the zero-bias conductance peak splitting in topological superconducting nanowires

• Jun-Tong Ren,
• Hai-Feng Lü,
• Sha-Sha Ke,
• Yong Guo and
• Huai-Wu Zhang

Beilstein J. Nanotechnol. 2018, 9, 1358–1369, doi:10.3762/bjnano.9.128

• ][41][42][43]. Secondly, theory predicts an increasing oscillation magnitude of Majorana energy splitting with the increase of magnetic field [36][44], while the experiment indicates the damped oscillation with increasing field. Similar discrepancy was also shown in the Majorana-quantum dot hybrid

Andreev spectrum and supercurrents in nanowire-based SNS junctions containing Majorana bound states

• Jorge Cayao,
• Annica M. Black-Schaffer,
• Elsa Prada and
• Ramón Aguado

Beilstein J. Nanotechnol. 2018, 9, 1339–1357, doi:10.3762/bjnano.9.127

• levels (belonging to γ1,4) and the dispersive levels (belonging to γ2,3) around = π depends on the overlap of MBSs on each topological segment. It can be used to quantify the degree of Majorana non-locality (a variant of this idea using quantum-dot parity crossings has been discussed in [55][56]). This

Computational exploration of two-dimensional silicon diarsenide and germanium arsenide for photovoltaic applications

• Sri Kasi Matta,
• Chunmei Zhang,
• Yalong Jiao,
• Anthony O'Mullane and
• Aijun Du

Beilstein J. Nanotechnol. 2018, 9, 1247–1253, doi:10.3762/bjnano.9.116

• . Additionally, the exciton binding energies are quite low and are comparable to quantum dot semiconductors. It might be possible that these semiconductors could be synthesized as quantum dots and studied in further detail. Band gap tuning appears also possible and could be used to tailor the compounds for

Thermoelectric current in topological insulator nanowires with impurities

• Sigurdur I. Erlingsson,
• Jens H. Bardarson and
• Andrei Manolescu

Beilstein J. Nanotechnol. 2018, 9, 1156–1161, doi:10.3762/bjnano.9.107

• thermoelectric current can be obtained when the temperature gradient is increased, which affects the population of the resonant level in the quantum dot [16][17][18][19]. For topological insulator nanowires one can expect reversed, or anomalous, currents measured in tens of nanoamperes [11], well within

Theoretical study of strain-dependent optical absorption in a doped self-assembled InAs/InGaAs/GaAs/AlGaAs quantum dot

• Tarek A. Ameen,
• Hesameddin Ilatikhameneh,
• Archana Tankasala,
• Yuling Hsueh,
• James Charles,
• Jim Fonseca,
• Michael Povolotskyi,
• Jun Oh Kim,
• Sanjay Krishna,
• Monica S. Allen,
• Jeffery W. Allen,
• Rajib Rahman and
• Gerhard Klimeck

Beilstein J. Nanotechnol. 2018, 9, 1075–1084, doi:10.3762/bjnano.9.99

• devices. We also show that for doped quantum dots, many-particle configuration interaction is also critical to accurately capture the optical transitions of the system. The sophisticated models presented in this work reproduce the experimental results for both undoped and doped quantum dot systems. The

• effects of alloy mole fraction of the strain controlling layer and quantum dot dimensions are discussed. Increasing the mole fraction of the strain controlling layer leads to a lower energy gap and a larger absorption wavelength. Surprisingly, the absorption wavelength is highly sensitive to the changes

• absorption; quantum qot filling; self-assembled quantum dots; semi-empirical tight-binding; sp3d5s* with spin–orbit coupling (sp3d5s*_SO); Introduction Self-assembled quantum dots are employed as light absorbers in many optoelectronic devices, such as quantum-dot infrared photodetectors (QDIPs) [1][2], and

Dynamic behavior of nematic liquid crystal mixtures with quantum dots in electric fields

• Emil Petrescu,
• Cristina Cirtoaje and
• Octavian Danila

Beilstein J. Nanotechnol. 2018, 9, 399–406, doi:10.3762/bjnano.9.39

• quantum dot surface. Dynamic experiments performed in alternating electric fields proved that by adding a small amount of CdSe/ZnS quantum dots in thermotropic nematic liquid crystal with positive dielectric anisotropy, we obtain a decrease of the relaxation time. When an external electric field higher

• permittivity, is the perpendicular permittivity. In this case H becomes: where d(z) the depolarization coefficient, which for an ellipsoid with almost spherical shape (horizontal axis equal b = R and vertical axis a = R + 0.0005R) is If a quantum dot is placed inside this cavity, another polarization field

• dielectric constant of the QDs (εQD) and the volumetric fraction of the quantum dots (cv). The intraction free energy between nematic molecules and a quantum dot can be calculated from the Rapini formula [21]. Considering an elliptical quantum dot with one of the axes just a little bit longer than the others

Nanoparticle delivery to metastatic breast cancer cells by nanoengineered mesenchymal stem cells

• Liga Saulite,
• Karlis Pleiko,
• Ineta Popena,
• Dominyka Dapkute,
• Ricardas Rotomskis and
• Una Riekstina

Beilstein J. Nanotechnol. 2018, 9, 321–332, doi:10.3762/bjnano.9.32

• study was to demonstrate that nanoengineered MSCs can serve as a delivery vehicle to target breast cancer cells in a 3D co-culture model. Results Optimal quantum dot labelling conditions in mesenchymal stem cells The flow cytometry data revealed that MSCs incubated in serum-free conditions accumulated

• ]. However, after 48 h, 72 h and 96 h propagation on polyHEMA coatings, CD90 expression was reduced to 92%, 81% and 88%, respectively (Figure 2C). Therefore, we chose 24 h as the optimal incubation time for 3D cell co-culture experiments to ensure the selectivity of the CD90 marker towards MSCs. Quantum dot

• subsequently more pronounced (Figure 3D). Thus, we chose to label MSCs with QDs in serum-free medium to ensure the highest load of intracellular QDs for further 3D co-culture experiments. Quantum dot uptake in breast cancer cell 2D and 3D monocultures MCF7 and MDA-MB-231 cells formed loose, floating aggregates

Review on optofluidic microreactors for artificial photosynthesis

• Xiaowen Huang,
• Jianchun Wang,
• Tenghao Li,
• Jianmei Wang,
• Min Xu,
• Weixing Yu,
• Abdel El Abed and
• Xuming Zhang

Beilstein J. Nanotechnol. 2018, 9, 30–41, doi:10.3762/bjnano.9.5

• splitting and CO2 reduction [80], but significant progress had already been made before it was combined with the optofluidics [81]. Park et al. developed CdS quantum-dot-sensitized TiO2 nanotube arrays for the photo-regeneration of nicotinamide cofactors [82]. They also used SiO2-supported CdS quantum dots

Beyond Moore’s technologies: operation principles of a superconductor alternative

• Igor I. Soloviev,
• Nikolay V. Klenov,
• Sergey V. Bakurskiy,
• Mikhail Yu. Kupriyanov,
• Alexander L. Gudkov and
• Anatoli S. Sidorenko

Beilstein J. Nanotechnol. 2017, 8, 2689–2710, doi:10.3762/bjnano.8.269

• different operating regime. It is interesting to note that the manner of parametric quantron cell operation was implemented later in a single-electron device [24][53] in 1996. The “single-electron parametron” operation was in fact quite similar to the ones of quantum-dot cellular automata (QCA) which were

PTFE-based microreactor system for the continuous synthesis of full-visible-spectrum emitting cesium lead halide perovskite nanocrystals

• Chengxi Zhang,
• Weiling Luan,
• Yuhang Yin and
• Fuqian Yang

Beilstein J. Nanotechnol. 2017, 8, 2521–2529, doi:10.3762/bjnano.8.252

• (XRD) measurements were performed on a Rigaku D/max2550 (Rigaku, USA) device operating with Cu Kα (λ = 0.154056 nm), and the QDs were spin-coated on fluorine-doped tin oxide glass. (a) Color luminescence under ultraviolet light and (b) photoluminescence of CsPbX3 quantum dot solutions. High-resolution

Hydrothermal synthesis of ZnO quantum dot/KNb₃O₈ nanosheet photocatalysts for reducing carbon dioxide to methanol

• Xiao Shao,
• Weiyue Xin and
• Xiaohong Yin

Beilstein J. Nanotechnol. 2017, 8, 2264–2270, doi:10.3762/bjnano.8.226

• loaded onto KNb3O8 nanosheets was characterized via TEM (Figure 4) and HRTEM (Figure 5). The crystalline ZnO quantum dot average diameter was about 10 nm and they were found dispersed on the surface of the KNb3O8 nanosheets. The HRTEM image revealed a lattice spacing of 0.282 nm (Figure 5), which clearly

• reflectance spectra for different amounts of ZnO quantum dots loaded onto KNb3O8 nanosheets are illustrated in Figure 7. The steep absorption edge of the pure KNb3O8 nanosheets occurred around 343 nm under UV light owing to its large intrinsic band gap. When increasing the ZnO quantum dot loading, the sample

• KNb3O8 nanosheets: (a) 0 wt %; (b) 1 wt %; (c) 2 wt %; (d) 3 wt %; (e) 4 wt %. TEM image of the 2 wt % ZnO quantum dot/KNb3O8 nanosheet composite photocatalyst. HRTEM image of the 2 wt % ZnO quantum dot/KNb3O8 nanosheet composite photocatalyst. Energy dispersive X-ray spectroscopy pattern of the 2 wt

Three-in-one approach towards efficient organic dye-sensitized solar cells: aggregation suppression, panchromatic absorption and resonance energy transfer

• Jayita Patwari,
• Samim Sardar,
• Bo Liu,
• Peter Lemmens and
• Samir Kumar Pal

Beilstein J. Nanotechnol. 2017, 8, 1705–1713, doi:10.3762/bjnano.8.171

• broad wavelength range without affecting the key parameters such as open circuit voltage (Voc) or fill factor (FF) of the DSSCs [23]. An enhancement in photocurrent due to efficient energy transfer from a quantum dot to the sensitizing dye has been reported earlier for quantum dot co-sensitized DSSCs

Two-dimensional carbon-based nanocomposites for photocatalytic energy generation and environmental remediation applications

• Suneel Kumar,
• Ashish Kumar,
• Ashish Bahuguna,
• Vipul Sharma and
• Venkata Krishnan

Beilstein J. Nanotechnol. 2017, 8, 1571–1600, doi:10.3762/bjnano.8.159

• . Feng et al. reported novel CdS quantum dot (QDs) coupled with g-C3N4 photocatalysts by a chemical impregnation method [16]. The reported photocatalyst was used for visible-light-based H2 evolution from an aqueous methanol solution with Pt as a cocatalyst. The effect of CdS loading was optimized to be