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

• indirect bandgap semiconductor, since the grains are small and the energy levels are discrete: In Equation 1, h is Plank’s constant (6.626 × 10−34 J s), ν is the frequency of light, and Eg represents the bandgap energy. For the calculation of Eg by the Tauc plot absorbance the value of the absorption (Abs

• narrowed under the action of LSPR and hot electron injection, and the samples have absorption peaks in the visible part. In Figure 6d, since Ag covers TiO2, the light absorption of ACT3 is substantially generated by Ag, so the sample has no bandgap. The photocatalytic reaction takes place on the surface of

• , 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

Structural optical and electrical properties of a transparent conductive ITO/Al–Ag/ITO multilayer contact

• Aliyu Kabiru Isiyaku,
• Ahmad Hadi Ali and
• Nafarizal Nayan

Beilstein J. Nanotechnol. 2020, 11, 695–702, doi:10.3762/bjnano.11.57

• excellent optical and electrical properties [4][5]. It is a wide-bandgap material (3.6–4.0 eV) with low electrical resistivity. ITO contains the rare and expensive metal indium, which is reflected in the market value of the material [6]. Hence, a reduction of the ITO consumption is desirable. ITO films with

Effect of substitutional defects on resonant tunneling diodes based on armchair graphene and boron nitride nanoribbons lateral heterojunctions

• Majid Sanaeepur

Beilstein J. Nanotechnol. 2020, 11, 688–694, doi:10.3762/bjnano.11.56

• heterojunctions of armchair graphene and boron nitride nanoribbons, exhibiting negative differential resistance is proposed. Low-bandgap armchair graphene nanoribbons and high-bandgap armchair boron nitride nanoribbons are used to design the well and the barrier region, respectively. The effect of all possible

• of applications including ultra-fast switching devices, oscillators, frequency multipliers, one-transistor static memories and multi-valued memory circuits [12][17][18][19][20]. In a RTD, a material with low bandgap energy is sandwiched between two materials with larger bandgaps, i.e., a quantum well

• rather high transmission probabilities. Electrons with other energies have an extremely small chance of passing through. This causes RTDs to exhibit NDR in their current–voltage characteristic. Conventionally, RTDs are made by vertical stacking of bulk semiconductor materials with different bandgap

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

• , photocatalytic purification might become the main means for the treatment of water and air pollutants [4]. Photocatalytic reactions on metal oxide semiconductors can degrade many pollutants and are, thus, of great interest [5]. Photogenerated charge carriers formed through bandgap excitation can reduce or

• semiconductor material to the other [7][8][9][10]. ZnO is a semiconductor material with a wide direct bandgap of 3.2 eV, which can absorb a small part of the solar spectrum in the UV region [11][12][13]. CuO is a nontoxic, chemically stable and naturally abundant material. It is a p-type semiconductor with a

• narrow direct bandgap of 1.2–1.79 eV [14]. Because of that, CuO is usually used in combination with large-bandgap semiconductors, such as ZnO and TiO2, in order to improve their photocatalytic activity under solar light irradiation [15]. It was reported that the p–n heterojunction between ZnO and CuO has

Soybean-derived blue photoluminescent carbon dots

• Shanshan Wang,
• Wei Sun,
• Dong-sheng Yang and
• Fuqian Yang

Beilstein J. Nanotechnol. 2020, 11, 606–619, doi:10.3762/bjnano.11.48

• synthesized from glassy carbon [16], graphite [26], polymethyl methacrylate (PMMA) [27], and a graphite–cement mixture [6] via LAL in various liquids. In general, there are three major mechanisms contributing to the photoluminescence (PL) of CDs: 1) size-dependent bandgap (quantum confinement), 2) surface

• carbonyl and other oxygen or nitrogen-containing groups [37]. There is no visible peak for the annealed-CDs, which exhibited continuous, weak absorbance in the wavelength range of 200 to 600 nm. Such a result suggests that the annealed-CDs are conductive and the corresponding bandgap is zero [38]. For the

• likely attributed to the fluctuations of the bandgap associated with the functional groups and the disorder of crystallinity introduced by the LAL processing. According to Yu et al. [42], the emission peak of CDs can be fitted with a two-Gaussian function, associated with the “core” state and “surface

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

• band (VB) and conduction band (CB) were determined using solid-state UV–vis measurements in combination with PESA. Similar to the determination of the HOMO, the VB can be determined with PESA. Solid-state reflection spectra of the LHPs give information about the bandgap energy Eg of the semiconductor

• successful functionalization. The UV–vis absorption spectra, shown in Figure 4F, confirm these findings. 3D-AzoC2 shows absorption maxima at 518 and 324 nm. The absorption at 518 nm is assigned to the excitonic bandgap of the perovskite. The absorption at 324 nm indicates the coordination of the azobenzene

• precipitate, which also known for other systems [47]. Because of this effect, the absorption of AzoC2 at 325 nm shows an exponential decay over the time of irradiation in relation to the excitonic bandgap at 524 nm. Thus, the drop in absorption at 325 nm signals indicates successful photoswitching. For a

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

• semiconductors, unlike graphene, and have thus garnered significant interest in the electronics industry [4]. Often, the properties of the monolayer are different from those of the bulk materials. For example, MoS2 has an indirect bandgap in its bulk structure, while it exhibits a direct bandgap as a monolayer

• depending on the computational setup, the authors conclude that the adsorption of noble metal chains allows for a small opening of the bandgap of graphene, although they are unable to interpret the exact mechanism by which this occurs. The adsorption of 29 atom nanoparticles of Cu, Ag and Au on a MoS2

Implementation of data-cube pump–probe KPFM on organic solar cells

• Benjamin Grévin,
• Olivier Bardagot and
• Renaud Demadrille

Beilstein J. Nanotechnol. 2020, 11, 323–337, doi:10.3762/bjnano.11.24

• -processed organic donor–acceptor blends called bulk heterojunctions (BHJ), for polycrystalline direct bandgap semiconductors such as CdTe, CuInxGa(1−x)Se2 and Cu2ZnSnS4 and for hybrid organic–inorganic perovskite solar cells. Whatever material used, improving the performance of the solar cell requires a

• charges. The latter can eventually reach the collection electrodes of the device. Here, the low-bandgap polymer PTB7 was used as the donor and the fullerene derivative PC71BM as the acceptor. In the BHJ configuration [26], the D and A materials should form two interpenetrated networks phase-segregated at

Recent progress in perovskite solar cells: the perovskite layer

• Xianfeng Dai,
• Ke Xu and
• Fanan Wei

Beilstein J. Nanotechnol. 2020, 11, 51–60, doi:10.3762/bjnano.11.5

• perovskites is lower than that of their 3D counterparts because of the lower carrier mobility, the wide optical bandgap, the low conductivity and the large exciton binding energy. Therefore, Priya et al. [8] created a methylammonium (MA)-based 2D perovskite film by using the vapor-fumigation technique. The

Synthesis and acetone sensing properties of ZnFe₂O₄/rGO gas sensors

• Kaidi Wu,
• Yifan Luo,
• Ying Li and
• Chao Zhang

Beilstein J. Nanotechnol. 2019, 10, 2516–2526, doi:10.3762/bjnano.10.242

• amounts of acetone still need to be enhanced. As a dual metal oxide, AB2O4 spinel materials received much attention in the field of gas sensing [13][14]. With a unique spinel structure and a narrow bandgap width (≈1.94 eV), zinc ferrite (ZnFe2O4) has remarkable properties and shows good potential in the

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

• be explained by the proportionality of the Seebeck coefficient to the bandgap [33]. Unlike the Seebeck coefficient, the electrical and thermal conductivities exhibit a clear anisotropic behavior which is attributed to the anisotropic relaxation time [17]. Figure 2b reveals that the electrical

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

• .10.190 Abstract Black phosphorus (BP) has a pressure-dependent bandgap width and shows the potential for applications as a low-dimensional pressure sensor. We built two kinds of pure BP devices with zigzag or armchair conformation, and explored their pressure-dependent conductance in detail by using

• the use as field-effect transistor [1][25][26][27][28]. Different from the planar 2D materials, such as graphene and silicene, the puckered configuration of BP makes structural deformation much easier by tension or compression along any direction. Meanwhile, large-scale bandgap modulation accompanied

• by high carrier mobilities can be realized, which are two main focuses of nanoscale electronic devices [1][3][7][13][25][29][30][31]. Previous studies indicated that BP can withstand a tensile stress as high as 10 N/m and a strain up to 30%, and exhibit a direct–indirect–direct bandgap phase

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

• intermolecular CT excitation between the C60 and TTF ligands, as supported by theoretical calculations (see below). The experimental optical bandgap calculated from the onset is near 1.4 eV (885 nm), which is in agreement with the calculated electrochemical bandgap (1.43 eV) since the redox potential of TTF

• 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

• to the relatively low bandgap, the nature of the frontier crystal orbitals and the close proximity between the electroactive donor TTF and acceptor C60 moieties, CT processes are expected upon light irradiation. Donor–acceptor interactions in C60@MUV-2 were first assessed at the ground state

Fabrication and characterization of Si_1−xGe_x nanocrystals in as-grown and annealed structures: a comparative study

• Muhammad Taha Sultan,
• Adrian Valentin Maraloiu,
• Ionel Stavarache,
• Jón Tómas Gudmundsson,
• Andrei Manolescu,
• Valentin Serban Teodorescu,
• Magdalena Lidia Ciurea and
• Halldór Gudfinnur Svavarsson

Beilstein J. Nanotechnol. 2019, 10, 1873–1882, doi:10.3762/bjnano.10.182

• the advantage of a bandgap fine-tuning by varying the Ge atomic fraction [5][6]. These properties are useful for optoelectronic devices working in the visible to far-infrared region [4][7]. Issues commonly observed with the fabrication of such structures include inhomogeneity at the matrix

• to surface polarization effects due to local fields, which play a crucial role in systems characterized by strong charge inhomogeneity. Further, the development of strain in the structure influences the size and shape of the NCs, thus resulting in a change of the bandgap energy. A common method to

• possible. An increased number of dangling bonds increases the number of localized states in the band structure along with an increase in non-radiative centers (Pb) [48][49]. This results in a broadening of the energy width of localized states with annealing temperature, resulting in bandgap alteration

Prestress-loading effect on the current–voltage characteristics of a piezoelectric p–n junction together with the corresponding mechanical tuning laws

• Wanli Yang,
• Shuaiqi Fan,
• Yuxing Liang and
• Yuantai Hu

Beilstein J. Nanotechnol. 2019, 10, 1833–1843, doi:10.3762/bjnano.10.178

• present are third-generation semiconductors, for instance, ZnO, GaN, CdS, and AlN, with wide bandgap, high breakdown electric field, high thermal conductivity, and even mechanical tunability [3]. They show numerous application prospects in electric devices and sensors, such as energy harvesters [4][5][6

Remarkable electronic and optical anisotropy of layered 1T’-WTe₂ 2D materials

• Qiankun Zhang,
• Rongjie Zhang,
• Jiancui Chen,
• Wanfu Shen,
• Chunhua An,
• Xiaodong Hu,
• Mingli Dong,
• Jing Liu and
• Lianqing Zhu

Beilstein J. Nanotechnol. 2019, 10, 1745–1753, doi:10.3762/bjnano.10.170

• its semi-metal bandgap structure and high anisotropy. In addition to angle-dependent photodetectors, its angle-resolved photoelectric properties may permit the development of plasmonic devices in which the surface plasmon polariton frequency has a highly directional dependence on the wave vector

• . Besides, the semi-metal bandgap structure allows various energy band engineering methods [36][37] to be explored for the promising application in electronic and photonic devices [38][39][40][41]. In general, due to its highly anisotropic nature, 1T’-WTe2 offers optimistic prospects for the applications in

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

• ]). Strontium titanate, SrTiO3, is a perfect example of a semiconductor with a wide bandgap of 3.2 eV and also a model perovskite oxide. Ti4+ cations provide no electrons for the d-band, which can participate in conductivity. Strontium titanate finds many applications as a dielectric ceramic material [15] but

Graphynes: an alternative lightweight solution for shock protection

• Kang Xia,
• Haifei Zhan,
• Aimin Ji,
• Jianli Shao,
• Yuantong Gu and
• Zhiyong Li

Beilstein J. Nanotechnol. 2019, 10, 1588–1595, doi:10.3762/bjnano.10.154

• [8]. GY has a non-zero bandgap, which indicates a potential application in next-generation carbon-based semiconductors [9]. In addition, the properties of GYs are highly tunable through the modification of the topology. For instance, GYs are found to absorb light in the HOMO–LUMO band and the energy

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

• treated ITO films is essential in assessing the advantages of the RTA procedure. To obtain information on the bandgap width, absorption coefficient, refractive index, extinction coefficient, dielectric permittivity, position of the impurity levels in the bandgap and characteristics of the optical

• transitions, we plotted and studied the transmission spectra of the ITO thin films (Figure 5). These polycrystalline thin films show considerable promise for integration into photovoltaic structures, having the bandgap width close to the optimum value of 3.7 eV [39]. Following the RTA process, the ITO thin

• energy of the oscillator, E0, and dispersion energy, Ed [44] as: where ν is the photon frequency. From the graphical representation (n2 − 1)−1 = f [(hν)2] we get the slope (E0Ed)−1, where E0 is considered to be an average of the bandgap energy of semiconductor and has the expression E0 ≈ 2Eg. The optical

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

• ]. Strelko et al. used theoretical methods to establish an interesting relationship between the bandgap energy of a given catalyst and its ability to promote reactions involving electron transfer [21]. Moreover, P-doping of graphitic layers was revealed to have an effect similar to that of N-doping and hence

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

• and high carrier utilization rate with slightly reduced bandgap, which will effectively improve the photocatalytic activity. According to the discussion and analysis of the above results, the possible degradation mechanism of RhB by BTD composites was demonstrated in Figure 11. The result shows that

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

• photocatalysis as an advanced green technology has been widely studied and applied for the removal of organic pollutants from water [1][2][3]. The catalytic activity of many wide-bandgap (Eg) semiconductor photocatalysts is restricted to UV light radiation, which is only 5% of the solar spectrum. Hence, the

• 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

• the absolute electronegativity of the photocatalyst, Ee is the energy of the free electrons (4.5 eV) on the hydrogen scale, and Eg is the bandgap width of the photocatalyst. Thus, the VB and CB positions of CBO are calculated to be about 1.13 eV and −0.63 eV, respectively. Under irradiation with

Green fabrication of lanthanide-doped hydroxide-based phosphors: Y(OH)₃:Eu³⁺ nanoparticles for white light generation

• Tugrul Guner,
• Anilcan Kus,
• Mehmet Ozcan,
• Aziz Genc,
• Hasan Sahin and
• Mustafa M. Demir

Beilstein J. Nanotechnol. 2019, 10, 1200–1210, doi:10.3762/bjnano.10.119

• bandgap of 3.83 eV, some midgap states emerge after the interstitial doping of Eu. The energy bandgap of the host at the vicinity of doped region increases to 4.28 eV. The band and orbital decomposed charge density presented in Figure 5b shows that the midgap state is formed by strongly hybridized Eu and

Photoactive nanoarchitectures based on clays incorporating TiO₂ and ZnO nanoparticles

• Eduardo Ruiz-Hitzky,
• Pilar Aranda,
• Marwa Akkari,
• Nithima Khaorapapong and
• Makoto Ogawa

Beilstein J. Nanotechnol. 2019, 10, 1140–1156, doi:10.3762/bjnano.10.114

• @montmorillonite materials can be synthesized from a Zn solution and cetyltrimethylammonium (CTA)-montmorillonite organoclays. In these materials, the bandgap energy of ZnO is decreased compared to bare ZnO NPs, which results in a faster photodegradation of MB. In experiments to prepare ZnO@clay nanoarchitectures

• perspectives Nanoparticulated TiO2 has almost the same bandgap characteristics than ZnO, with bandgap energies of 3.20 eV and 3.37 eV, respectively [48][134][135][136]. Therefore, the photocatalytic capability of both types of NPs should be quite similar. Apart from these large bandgap energy values, both

• transition metals or with other semiconductors. Among them, semiconductor heterojunctions have attracted great attention [139]. The doping of TiO2 and ZnO NPs with the aim to conveniently tuning the bandgap energy values can be a suitable option. In this context, it has been verified for both types of NPs, a

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

• bandgap and in agreement with the distribution of sizes. A blue-shift of the luminescence is observed as the average size of the nanodots gets smaller, evidencing quantum confinement in all samples. By using simple quantum confinement calculations, we correlate the photoluminescence peak emission energy

• formation of a Cu–In–Se ordered defect compound, which has been reported to form along the tie-line of the (Cu2Se)x–(In2Se3)1−x pseudo-binary system [38][39], and which has a bandgap energy very close to that of CuInSe2 [40]. In this compositional region, i.e., low amounts of Cu compared with In, the so

• show in detail the spectra in Figure 4c–e. The dashed line indicates the bulk bandgap of CIS (1.04–1.05 eV) [45][46]. It is clear that all samples show peak emission at energies above the bulk bandgap, which we preliminarily explain by a quantum confinement effect due to the small mean size of the