Near-infrared photoactive Ag-Zn-Ga-S-Se quantum dots for high-performance quantum dot-sensitized solar cells

• Roopakala Kottayi,
• Ilangovan Veerappan and
• Ramadasse Sittaramane

Beilstein J. Nanotechnol. 2022, 13, 1337–1344, doi:10.3762/bjnano.13.110

• surface trap state defects [11][12]. In order to minimize the number of these defects, a wide-bandgap material, such as ZnS or ZnSe, is deposited on group I-III-VI QDs. Zhang et al. over coated a ZnS layer [13][14] on Cu-In-S and Cu-In-Se QDs to obtain highly efficient sensitizers for QDSCs. Hua Zhang et

• [16]. Recently, Larsen et al. reported that, due to the appropriate bandgap (1.6–1.8 eV), AgGaSe2 is a wide-range light absorber in thin film solar cells [17]. Tianya Bai et al. [18] examined that ZnS-coated AgGaS2 nanocrystals (AgGaS2/ZnS core–shell nanocrystals) have a tunable bandgap and PL colors

• spectrum of colloidal AZGSSe QDs (Figure 4a) reveals a wide absorption range in the near-infrared (NIR) region. This confirms the NIR photoactive nature of the synthesized QDs. Figure 4b depicts the Tauc plot [30] of the synthesized QDs. From this, the bandgap energy of AZGSSe QDs was found to be 1.37 eV

Recent trends in Bi-based nanomaterials: challenges, fabrication, enhancement techniques, and environmental applications

• Vishal Dutta,
• Ankush Chauhan,
• Ritesh Verma,
• C. Gopalkrishnan and
• Van-Huy Nguyen

Beilstein J. Nanotechnol. 2022, 13, 1316–1336, doi:10.3762/bjnano.13.109

• environmentally beneficial alternatives [7]. The choice of the photocatalysts is one of the most important steps in attaining high performance in photocatalysis. Semiconductors with bandgaps greater than 3 eV are called wide-bandgap photocatalysts. These semiconductors include oxides (e.g., TiO2, Bi2O3, Bi2WO6

• , and SrTiO3), sulfates (e.g., MoS2 and Bi2S3), selenides (e.g., MoSe2 and CdSe), and phosphates (e.g., Ag3PO4) [8][9][10][11][12][13][14][15]. The bandgap of photocatalysts sensitive to visible light is smaller than 3 eV. Wide-bandgap photocatalysts can only be stimulated by ultraviolet light, which

• oxides, and binary Bi sulfides. Bismuth oxyhalides are indirect bandgap semiconductors in which photogenerated electrons and holes rarely recombine. BiOX is an excellent photocatalyst, and it is widely applied due to its small bandgap and high electron density, which are easily adjustable by changing the

Enhanced electronic transport properties of Te roll-like nanostructures

• E. R. Viana,
• N. Cifuentes and
• J. C. González

Beilstein J. Nanotechnol. 2022, 13, 1284–1291, doi:10.3762/bjnano.13.106

• Earth’s crust and a well-known p-type and narrow-bandgap (≈0.35 eV at room temperature) semiconductor material. Tellurium is widely used in thermoelectric devices, piezoelectric devices, photoconductive devices, gas sensing, nonlinear optical devices, solar cells, photonic crystals, holographic recording

Rapid fabrication of MgO@g-C₃N₄ heterojunctions for photocatalytic nitric oxide removal

• Minh-Thuan Pham,
• Duyen P. H. Tran,
• Xuan-Thanh Bui and
• Sheng-Jie You

Beilstein J. Nanotechnol. 2022, 13, 1141–1154, doi:10.3762/bjnano.13.96

• spectroscopy (DRS) was used to determine the optical properties and bandgap energies of the material. The bandgap of the material decreases with increasing amounts of MgO. The photoluminescence spectra indicate that the recombination of electron–hole pairs is hindered by doping MgO onto g-C3N4. Also, NO

• absorbs visible light due to its small bandgap below 2.7 eV. Because of this, it has been consistently regarded as a catalyst with excellent optical properties [14][15]. Unfortunately, its narrow bandgap leads to rapid recombination of electron–hole (e−–h+) pairs, and the valence band potential of g-C3N4

• oxide with wide bandgap (3.5–5 eV), high availability, non-toxicity, low cost, and native structural defects [18][19]. The large bandgap energy is the limitation of MgO, reducing the photocatalytic performance and applicability of MgO [20]. Various efforts have been made to enhance the absorption in the

Green synthesis of zinc oxide nanoparticles toward highly efficient photocatalysis and antibacterial application

• Vo Thi Thu Nhu,
• Nguyen Duy Dat,
• Le-Minh Tam and
• Nguyen Hoang Phuong

Beilstein J. Nanotechnol. 2022, 13, 1108–1119, doi:10.3762/bjnano.13.94

• approach for the complete removal of organic pollutants due to their advantages. Semiconductors can act as catalysts for the complete degradation of organic substances when excited by light with an energy value higher than their bandgap. Among many semiconductors, TiO2 and ZnO are widely used as

• the use of ZnO catalysts occurs when ZnO is illuminated by light. When excited by light with an energy greater than the bandgap of ZnO, electrons from the valence band (VB) are excited to the conduction band (CB) to form photogenerated electrons in the CB and photogenerated holes in the VB [11][12

• dihydrate and synthesized ZnO NPs with sizes in the range of 9–18 nm. UV–vis DRS spectra of ZnO were shown in Figure 6a. ZnO absorbs light in the ultraviolet region. The bandgap energy of synthesized ZnO was determined by extrapolation of the linear part of the curve (α·hν)2 as a function of photon energy

Spindle-like MIL101(Fe) decorated with Bi₂O₃ nanoparticles for enhanced degradation of chlortetracycline under visible-light irradiation

• Chen-chen Hao,
• Fang-yan Chen,
• Kun Bian,
• Yu-bin Tang and
• Wei-long Shi

Beilstein J. Nanotechnol. 2022, 13, 1038–1050, doi:10.3762/bjnano.13.91

• be improved by combining it with other suitable semiconductor materials to construct Z-scheme heterojunctions. Bismuth trioxide (Bi2O3), a metal oxide semiconductor with a bandgap of 2.8 eV, can be excited by visible light [43][44]. However, pure Bi2O3 exhibits poor photocatalytic activity due to the

• investigate the optical response and bandgap of the prepared samples, UV–vis diffuse reflectance (UV–vis DRS) spectra were recorded and given in Figure 5. As seen from Figure 5a, both Bi2O3 and MIL101(Fe) show strong visible-light response with absorption edge of 460 nm and 510 nm, respectively. Compared with

• holes. The bandgap (Eg) of a semiconductor is usually estimated by the Tauc formula (αhν) = A(hv − Eg)n/2, where α is the absorbance, hν is the photon energy, A is a constant, Eg is the bandgap , and n is a constant. For Bi2O3 and MIL101(Fe), as direct bandgap semiconductors, the value of n is 1 [58

Numerical study on all-optical modulation characteristics of quantum cascade lasers

• Biao Wei,
• Haijun Zhou,
• Guangxiang Li and
• Bin Tang

Beilstein J. Nanotechnol. 2022, 13, 1011–1019, doi:10.3762/bjnano.13.88

• ,i are the electron lifetimes in A3 with and without injected light, respectively, and Kb is the Boltzmann constant. To determine ΔT, we assume that all the energy of the optically excited electrons, except those that overcome the bandgap, converts to the kinetic energy of the electrons in the cavity

• . So the kinetic energy of a single optically excited electron E can be described by the following function (it can be verified by the well-known Fermi–Dirac distribution function): And E can be described as where Eg is the bandgap. So the average variation in electron temperature can be described as

Theoretical investigations of oxygen vacancy effects in nickel-doped zirconia from ab initio XANES spectroscopy at the oxygen K-edge

• Dick Hartmann Douma,
• Lodvert Tchibota Poaty,
• Alessio Lamperti,
• Stéphane Kenmoe,
• Abdulrafiu Tunde Raji,
• Alberto Debernardi and
• Bernard M’Passi-Mabiala

Beilstein J. Nanotechnol. 2022, 13, 975–985, doi:10.3762/bjnano.13.85

• stoichiometric concentration required to ensure overall charge neutrality can modify the presence of defect states in the electron bandgap [4][26][27]. In diluted magnetic semiconductors (DMS), magnetic impurities such as the transition metals (TM) Fe or Ni are introduced to produce a magnetic ground state. The

Solar-light-driven LaFe_xNi_1−xO₃ perovskite oxides for photocatalytic Fenton-like reaction to degrade organic pollutants

• Chao-Wei Huang,
• Shu-Yu Hsu,
• Jun-Han Lin,
• Yun Jhou,
• Wei-Yu Chen,
• Kun-Yi Andrew Lin,
• Yu-Tang Lin and
• Van-Huy Nguyen

Beilstein J. Nanotechnol. 2022, 13, 882–895, doi:10.3762/bjnano.13.79

• essential role in photocatalytic reactions for wastewater [38]. Fe doping of LaNiO3 revealed the potential of tuning bandgap and boosting the light absorption to degrade RhB [39]. However, little literature comprehensively and systematically discusses the effect of different doping ratios on photocatalytic

Efficient liquid exfoliation of KP₁₅ nanowires aided by Hansen's empirical theory

• Zhaoxuan Huang,
• Zhikang Jiang,
• Nan Tian,
• Disheng Yao,
• Fei Long,
• Yanhan Yang and
• Danmin Liu

Beilstein J. Nanotechnol. 2022, 13, 788–795, doi:10.3762/bjnano.13.69

• the concentration of the KP15 dispersions. The absorbance A and the absorption coefficient K are related to the wavelength of the incident light. To determine A and K, it is necessary to choose a specific incident wavelength. The bandgap of bulk KP15 is approx. 1.75 eV [20]. However, according to our

• influence of the surface state, a wavelength (800 nm) which is far away from the bandgap of KP15 bulk and surface state in the KP15 nanowires was chosen. Some dispersions for which we predetermined the concentration were prepared to fit and determine the absorption coefficient K. Solutions of five different

Recent advances in nanoarchitectures of monocrystalline coordination polymers through confined assembly

• Lingling Xia,
• Qinyue Wang and
• Ming Hu

Beilstein J. Nanotechnol. 2022, 13, 763–777, doi:10.3762/bjnano.13.67

• packing than spherical particles. In addition, their porous structure can accommodate guest molecules, which can further alternate the properties of the whole assembly. These features give the assembled superstructures more freedom to change their properties, such as the photonic bandgap, which has been

Hierarchical Bi₂WO₆/TiO₂-nanotube composites derived from natural cellulose for visible-light photocatalytic treatment of pollutants

• Zehao Lin,
• Zhan Yang and
• Jianguo Huang

Beilstein J. Nanotechnol. 2022, 13, 745–762, doi:10.3762/bjnano.13.66

• ][8]. However, the wide bandgap of TiO2 inhibits the absorption of light in the visible region and the rapid recombination of photogenerated electron−hole pairs restrains its photocatalytic activity. It has been verified that constructing TiO2-based heterostructured composites by using visible-light

• (Supporting Information File 1, Figure S7), the cellulose-derived 70%−Bi2WO6/TiO2-NT nanocomposite possesses wider absorption edge in the UV–vis DRS, corresponding narrower bandgap, and weaker PL intensity in the PL spectra, suggesting stronger response to visible light and more efficient separation of the

Direct measurement of surface photovoltage by AC bias Kelvin probe force microscopy

• Masato Miyazaki,
• Yasuhiro Sugawara and
• Yan Jun Li

Beilstein J. Nanotechnol. 2022, 13, 712–720, doi:10.3762/bjnano.13.63

• [41][42][43][44]. Rutile TiO2 has a bandgap of 3.0 eV [45] and shows the SPV under UV illumination [46][47][48]. A clean rutile TiO2(110) surface (Crystal Base) was prepared by several cycles of Ar+ sputtering (1 keV, 1 × 10−6 Torr, 15 min) and annealing (993 K, less than 2 × 10−10 Torr, 30 min

Sodium doping in brookite TiO₂ enhances its photocatalytic activity

• Boxiang Zhuang,
• Honglong Shi,
• Honglei Zhang and
• Zeqian Zhang

Beilstein J. Nanotechnol. 2022, 13, 599–609, doi:10.3762/bjnano.13.52

• mixes with anatase or rutile [14][15]. (2) The bandgap Eg is important for the photocatalytic behavior of brookite TiO2; however, the precise value of Eg is still unknown. The measured Eg value varies from 1.9 to 3.4 eV [16][17], and the theoretical value ranges from 1.8 to 3.3 eV [18]. (3) The

• , the reaction rate constant in this report was about three times higher than that of the quasi-spherical brookite TiO2 (k = 0.0206) [22]. The excellent photocatalytic activity can be correlated with the crystal structure, micromorphology, and chemical composition [23][24][25]. The bandgap is useful to

• understand the photocatalytic behavior of a given material. The bandgap values were determined from the diffuse reflectance spectra using the Tauc plot method [26]: where A in Equation 1 is a proportional constant, α is the absorption coefficient, and n depends on the type of electron transition. The bandgap

Revealing local structural properties of an atomically thin MoSe₂ surface using optical microscopy

• Lin Pan,
• Peng Miao,
• Anke Horneber,
• Alfred J. Meixner,
• Pierre-Michel Adam and
• Dai Zhang

Beilstein J. Nanotechnol. 2022, 13, 572–581, doi:10.3762/bjnano.13.49

• fascinating optical and electronic properties [1]. In particular, the optical absorption, direct bandgap, and broken inversion symmetry of 2D transition-metal dichalcogenide (2D-TMDC) monolayers make these materials promising candidates for light-emitting diodes, photodetectors, field-effect transistors

• all Raman peaks. This is attributed to the fact that these vibrational modes possess large dipoles leading to a strong dipole–dipole interaction with the underlying h-BN. The MoSe2 monolayer used in our work is a direct-bandgap semiconductor and has a polar covalent bond (Mo–Se). The Raman peaks of

• region (bilayer) and the center position (monolayer) of CuPc on MoSe2 flake. The photoluminescence peak is due to the direct bandgap emission in the MoSe2 monolayer. (c) A sketch of the energy level diagram at the interface between CuPc molecule and 2H MoSe2 monolayer. The ground-state charge transfer

Zinc oxide nanostructures for fluorescence and Raman signal enhancement: a review

• Ioana Marica,
• Fran Nekvapil,
• Maria Ștefan,
• Cosmin Farcău and
• Alexandra Falamaș

Beilstein J. Nanotechnol. 2022, 13, 472–490, doi:10.3762/bjnano.13.40

• their wide bandgap energy (3.3–3.7 eV), strong luminescence [4][5], antibacterial properties, and UV-protection properties. Additionally, ZnO nanomaterials can be designed into various morphologies, such as nanoparticles, nanoneedles, nanorods, nanocages, nanocombs, and nanoflowers [5][6][7][8]. Hybrid

• shapes used for SERS applications, as well as spherical ZnO nanoparticles [8] are given in Figure 1. Combination of ZnO nanostructures with noble metals The use of inexpensive semiconducting materials, such as wide-bandgap ZnO or TiO2, for SPR-based substrates has gained increased attention in recent

• decrease of the bandgap of ZnO. All of these are contributing to the SERS enhancement. A SERS substrate enhancement factor of 5.4 × 107 and an analytical enhancement factor of 1.3 × 1010 were obtained with Ag–ZnO heterostructures on glass substrates for the detection of methylene orange molecules. These

Selected properties of Al_xZn_yO thin films prepared by reactive pulsed magnetron sputtering using a two-element Zn/Al target

• Witold Posadowski,
• Artur Wiatrowski,
• Jarosław Domaradzki and
• Michał Mazur

Beilstein J. Nanotechnol. 2022, 13, 344–354, doi:10.3762/bjnano.13.29

• shorter wavelengths, from about 370 to 342 nm (Figure 5b). The measured light transmission characteristics were further used to determine the thickness and the optical bandgap energy of the prepared films. For the analysis, the reverse synthesis method was applied. The analysis allowed for simultaneous

• distance of about 70 mm from the target axis. Therefore, one can conclude that the area for the substrate placement with favorable conditions for the preparation of transparent and well-conductive films is located outside the radial boundary of the target. The analysis of the optical bandgap energy (Eg) as

• a function of X for the films deposited at the front side of the substrate is presented in Figure 8. As one can see, with increasing X, the optical bandgap increased from about 3.10 to about 3.55 eV. Such a large change suggests a relatively large change in the material composition, which will be

The effect of metal surface nanomorphology on the output performance of a TENG

• Yiru Wang,
• Xin Zhao,
• Yang Liu and
• Wenjun Zhou

Beilstein J. Nanotechnol. 2022, 13, 298–312, doi:10.3762/bjnano.13.25

• –semiconductor and semiconductor–metal contact pairs [14][15]. A semiconductor–metal contact can be described by the band diagram shown in Figure 1. The frictional electrical properties of materials depend on their work functions and Fermi levels [16][17]. The intermediate state in the bandgap can reduce the

Investigation of a memory effect in a Au/(Ti–Cu)Ox-gradient thin film/TiAlV structure

• Damian Wojcieszak,
• Jarosław Domaradzki,
• Michał Mazur,
• Tomasz Kotwica and
• Danuta Kaczmarek

Beilstein J. Nanotechnol. 2022, 13, 265–273, doi:10.3762/bjnano.13.21

• resistive switching behavior. Results of optical, X-ray, and ultraviolet photoelectron spectroscopy measurements allowed us to elaborate the scheme of the bandgap alignment of the prepared thin films with respect to the Au and TiAlV electrical contacts. Detailed structure and elemental profile

• and reaches 40% on average. Visible maxima and minima result from multiple interferences of the light reflected from interfaces between air and thin film and thin film and SiO2 substrate. From the optical spectra, an optical bandgap width of about 2.8 eV was determined for the allowed indirect

• spectrum as marked in Figure 7a; it is 1.20 eV below the Fermi level (EF). Taking into consideration the bandgap energy of the thin films equal to 2.80 eV, the thin film surface exhibits p-type conduction. The electron affinity (χ) of the thin film surface was equal to 2.41 eV and was calculated based on

Engineered titania nanomaterials in advanced clinical applications

• Padmavati Sahare,
• Paulina Govea Alvarez,
• Juan Manual Sanchez Yanez,
• Gabriel Luna-Bárcenas,
• Samik Chakraborty,
• Sujay Paul and
• Miriam Estevez

Beilstein J. Nanotechnol. 2022, 13, 201–218, doi:10.3762/bjnano.13.15

• therapy. The cytotoxic properties of TiO2 are related to differences in phase composition. The anatase phase has a higher toxicity due to its wider bandgap and effectiveness in the generation of ROS [27]. Lower amounts of ROS, which operate as redox signaling messengers, are essential for optimal

• direct route for both bandgap engineering and photoactivity enhancement. One strategy employed was high-pressure and high-temperature hydrogenation, resulting in reduced “black TiO2” (B-TiO2−x) nps with a crystalline center and a disordered surface that absorbs light in the visible range. Chen et al

Theoretical understanding of electronic and mechanical properties of 1T′ transition metal dichalcogenide crystals

• Seyedeh Alieh Kazemi,
• Sadegh Imani Yengejeh,
• Vei Wang,
• William Wen and
• Yun Wang

Beilstein J. Nanotechnol. 2022, 13, 160–171, doi:10.3762/bjnano.13.11

• well-known differences between these two phases is their electronic properties. Using MoS2 as an example, its 1T′ and 2H polytypes are discussed by presenting their DOS and band structure, as illustrated in Figure 5a. There is a bandgap in the 2H polytype, which indicates that it is a semiconductor. On

A comprehensive review on electrospun nanohybrid membranes for wastewater treatment

• Senuri Kumarage,
• Imalka Munaweera and
• Nilwala Kottegoda

Beilstein J. Nanotechnol. 2022, 13, 137–159, doi:10.3762/bjnano.13.10

A photonic crystal material for the online detection of nonpolar hydrocarbon vapors

• Evgenii S. Bolshakov,
• Aleksander V. Ivanov,
• Andrei A. Kozlov,
• Anton S. Aksenov,
• Elena V. Isanbaeva,
• Sergei E. Kushnir,
• Aleksei D. Yapryntsev,
• Aleksander E. Baranchikov and
• Yury A. Zolotov

Beilstein J. Nanotechnol. 2022, 13, 127–136, doi:10.3762/bjnano.13.9

• qualitative detection of saturated vapors of volatile organic compounds due to configuration changes of the photonic bandgap, recorded by diffuse reflectance spectroscopy. The exposure of the sensor to aromatic (benzene, toluene and p-xylene) and aliphatic (n-pentane, n-heptane, n-octane and n-decane

• removed, then it is an inverse opal structure [11][12][13]. A photonic bandgap (PBG) appears in colloidal crystals due to the periodic modulation of the refractive index. At the bandgap, selective reflection of light is observed, which is connected to a low photon density of states within the materials

• [14]. Most of the configuration changes of the photonic bandgap in opal and inverse opal structures occur due to swelling or compression of the polymer matrix or gel. To date, four main methods for the modification of photonic crystals are used for the creation of stimuli-responsive materials: (a

Tin dioxide nanomaterial-based photocatalysts for nitrogen oxide oxidation: a review

• Viet Van Pham,
• Hong-Huy Tran,
• Thao Kim Truong and
• Thi Minh Cao

Beilstein J. Nanotechnol. 2022, 13, 96–113, doi:10.3762/bjnano.13.7

• morphology. Recent studies have been focused on the modification of properties of SnO2 to increase the photocatalytic efficiency of SnO2, including bandgap engineering, defect regulation, surface engineering, heterojunction construction, and using co-catalysts, which will be thoroughly highlighted in this

• morphology [25][26][27][28][29][30]. However, pure SnO2 suffers from some inherent drawbacks that limit its practical applications. With a wide bandgap (3.5–3.7 eV) [31][32], SnO2 can only be excited by UV irradiation. As a typical oxidation photocatalyst with the CB edge energy level, which is not conducive

• depends on many factors, including the structure and energy band, surface and defect states, morphology, etc. For that reason, recent studies are being focused on the modification of properties of SnO2 to upgrade the photocatalytic efficiency of SnO2, including bandgap engineering, defect regulation

Chemical vapor deposition of germanium-rich CrGe_x nanowires

• Vladislav Dřínek,
• Stanislav Tiagulskyi,
• Roman Yatskiv,
• Jan Grym,
• Radek Fajgar,
• Věra Jandová,
• Martin Koštejn and
• Jaroslav Kupčík

Beilstein J. Nanotechnol. 2021, 12, 1365–1371, doi:10.3762/bjnano.12.100

• undoped Ge nanowires or intrinsic bulk germanium [21]. One of the possible explanations is that Cr can form deep levels within the Ge bandgap [22]. These levels act as recombination centers and increase the resistivity. However, a precise determination of the influence of Cr incorporation on the