Oriented zinc oxide nanorods: A novel saturable absorber for lasers in the near-infrared

• Pavel Loiko,
• Tanujjal Bora,
• Josep Maria Serres,
• Haohai Yu,
• Magdalena Aguiló,
• Francesc Díaz,
• Uwe Griebner,
• Valentin Petrov,
• Xavier Mateos and
• Joydeep Dutta

Beilstein J. Nanotechnol. 2018, 9, 2730–2740, doi:10.3762/bjnano.9.255

• + and O2− ions stacked along the [001]-axis. Thus, there are many options to accommodate intrinsic defects (e.g., interstitial Zn2+ ions, Zni, or O2− vacancies, VO, which are the most widespread ones), as well as external dopants (e.g., divalent transition-metal ions M2+ entering into the Td sites

• were grown hydrothermally (in oxygen-rich conditions) one can expect the presence of zinc vacancies that have a low formation energy under such conditions. The singly charged zinc vacancy (VZn−1) is typically located at 0.8–0.9 eV above the ZnO valence band (VB) [9][33][34]. This defect site can be a

• possible source for the near-IR absorption. For longer NRs, one can expect more VZn−1 vacancies and stronger near-IR absorption, in agreement with Figure 3a. In Figure 3c, we compare the small-signal absorption spectra of ZnO NRs grown for 10 h and several well-known nanostructured “fast” SAs, namely a

Disorder in H⁺-irradiated HOPG: effect of impinging energy and dose on Raman D-band splitting and surface topography

• Lisandro Venosta,
• Noelia Bajales,
• Sergio Suárez and
• Paula G. Bercoff

Beilstein J. Nanotechnol. 2018, 9, 2708–2717, doi:10.3762/bjnano.9.253

• . [35] identified the type of defects generated in different HOPG samples and were able to relate the corresponding ID/IG-vs-ID′/IG ratios to different kinds of defects. They found that ID/ID′ ≈ 13 is related to sp3-hybridized sites in fluorinated graphene, ID/ID′ ≈ 7 refers to vacancies in ion

• sub-band represents a different group of defects. Based on these results for graphene, we claim that D1, with the lowest slope (1.6 ± 0.2), could be related to boundary-like defects in HOPG, while D2, with a slope of (4.4 ± 0.2), could be associated to vacancies and armchair edges [5][12][36], and to

• work, while the dashed, dashed-dotted and dotted lines are taken from Eckmann and co-workers [35]. The symbols +, * and # refer to sp3-hybridized bonds, vacancies, and boundary defects, respectively. a) Hysteresis loops of pristine HOPG and irradiated samples with low (LD) and high (HD) H+ doses, in

Impact of the anodization time on the photocatalytic activity of TiO₂ nanotubes

• Jesús A. Díaz-Real,
• Geyla C. Dubed-Bandomo,
• Juan Galindo-de-la-Rosa,
• Luis G. Arriaga,
• Janet Ledesma-García and
• Nicolas Alonso-Vante

Beilstein J. Nanotechnol. 2018, 9, 2628–2643, doi:10.3762/bjnano.9.244

• is supported by the fact that atomic radii for O (48 pm) and F (42 pm) are similar enough to allow for the replacement of the former, effectively doping the material by creating oxygen vacancies and different energy states [29]. XPS To characterize the surface chemistry, high-resolution XPS

• ca. 20% compared to the measurement in N2-saturated electrolyte, revealing the scavenging action of dissolved oxygen. While electrons are generated and collected in the outer circuit, electron vacancies (holes, h+) are left behind in the valence band of the material, which have an elevated oxidation

• N and F. Nevertheless, some physical phenomena such as light scattering (from the top part of the TNTs) and oxygen vacancies could also create distortions in the IPCE spectra. Furthermore, the bandgap (Eg) can be obtained from the Tauc plots, Figure 7b, plotting jph as a function of the wavelength

Exploring the photoleakage current and photoinduced negative bias instability in amorphous InGaZnO thin-film transistors with various active layer thicknesses

• Dapeng Wang and
• Mamoru Furuta

Beilstein J. Nanotechnol. 2018, 9, 2573–2580, doi:10.3762/bjnano.9.239

• oxygen-related defects, such as oxygen vacancies (VO), may be the origin of high-density electron traps near the EV in a-IGZO TFTs, which occupy the region near the valence band maximum with an energy width of ≈1.5 eV [26][27]. Figure 3a–d shows the variation in the transfer characteristics of a-IGZO

• required for the transition from VO to VO+ and VO2+, respectively. Moreover, the ionized oxygen vacancies of VO+ and VO2+ are located near the mid-gap and the bottom of the EC [15][29], respectively. It is sufficient to excite high-density VO defects to VO+/VO2+ and then to generate free electrons to EC

• oxygen vacancies in the bulk of the IGZO for the enhancement of electrical properties and stress stability of the TFTs, the following two aspects should be mainly considered: (i) oxidizing the densities of the defect state of oxide semiconductors to suppress charge trapping, for example by oxygen

Improved catalytic combustion of methane using CuO nanobelts with predominantly (001) surfaces

• Qingquan Kong,
• Yichun Yin,
• Bing Xue,
• Yonggang Jin,
• Wei Feng,
• Zhi-Gang Chen,
• Shi Su and
• Chenghua Sun

Beilstein J. Nanotechnol. 2018, 9, 2526–2532, doi:10.3762/bjnano.9.235

• indicates that the key role of OV is to activate O2 and release a highly active oxygen atom, although a barrier of 0.91 eV is found for O2 dissociation in the case of CuO(001), but the dehydrogenation from CHx becomes exothermic, confirming the importance of surface oxygen and oxygen vacancies, as suggested

Thickness-dependent photoelectrochemical properties of a semitransparent Co₃O₄ photocathode

• Malkeshkumar Patel and
• Joondong Kim

Beilstein J. Nanotechnol. 2018, 9, 2432–2442, doi:10.3762/bjnano.9.228

• octahedral (Co3+) and tetrahedral (Co2+) cobalt sites, where Co vacancies are the dominant sources of the p-type conductivity of Co3O4 under oxygen-rich conditions [9][13]. Despite these interesting properties of Co3O4 its application in photocathodes has been rarely studied [18][19][20][21][22][23

Lead-free hybrid perovskites for photovoltaics

• Oleksandr Stroyuk

Beilstein J. Nanotechnol. 2018, 9, 2209–2235, doi:10.3762/bjnano.9.207

• perovskite layer under a reductive atmosphere, for example, in the presence of hydrazine vapors [119]. The conversion of Sn4+ into Sn2+, which can be described as 2SnI62– + N2H4 = 2SnI42– + N2 + 2HI, results in a reduction of the density of Sn2+ vacancies (Figure 5a) suppressing the undesirable p-type

• trap-mediated non-radiative recombination losses. The effect of elimination of Sn2+ vacancies in FASnI3 HP resulting from tin(II) oxidation can also be achieved by a partial substitution of iodide with bromide [120]. The devices with a mixed Br/I halide component displayed a reduced dark current and

• lower recombination rate, resulting in an increased Voc and FF and showed a PCE above 5%, whereby the cells retained stability over a 1000 h time trial span [120]. In a similar manner, the mixed CsSnIBr2 HP revealed a higher stability and a lower density of Sn2+ vacancies which can be further decreased

Electrospun one-dimensional nanostructures: a new horizon for gas sensing materials

• Muhammad Imran,
• Nunzio Motta and
• Mahnaz Shafiei

Beilstein J. Nanotechnol. 2018, 9, 2128–2170, doi:10.3762/bjnano.9.202

• ]. Al-doped SnO2 NTs exhibit a high response to low concentrations of formaldehyde by Sn4+ by Al3+ in a SnO2 lattice as well as increase in oxygen vacancies [184]. Pure and 8Al-Sn NTs (i.e., the Al/(Al + Sn) ratio is 8%) have nearly the same average diameter (120 nm inner diameter and 200 nm outer

• to 64.9 due to an increase in oxygen vacancies. The response and the recovery time are about 7 s and 30 s, respectively [179]. WO3 NFs/NTs functionalized by Pt [168][187], Pd [107][188], Cu [101], Ru [189], Rh2O3 [106], Au NPs [109], RuO2 NPs [189], La2O3 [104] as well as Pd-loaded ZnO nanocubes [1

• resulting in high oxygen vacancies [215]. Similarly, Nd-doped In2O3 NTs showed enhanced formaldehyde sensing due to their porous and cracked morphology. Nd-doped In2O3 NTs have an average diameter of 200 nm as shown in Figure 10a–c. The optimum doping amount of Nd was 11 mol %. Nd-doped In2O3 porous NTs

Metal-free catalysis based on nitrogen-doped carbon nanomaterials: a photoelectron spectroscopy point of view

• Mattia Scardamaglia and
• Carla Bittencourt

Beilstein J. Nanotechnol. 2018, 9, 2015–2031, doi:10.3762/bjnano.9.191

• . Indeed, the graphitic network can be easily modified by the introduction of heteroatoms, functional groups or defects, such as dislocations, vacancies or edges [25][34][35]. They act as active sites for electron localization or they are useful to anchor metal clusters or foreign molecules that will, in

• the electronic states of graphene. In general, point defects generate localized states at the Fermi level, easily identifiable as protrusion by scanning tunneling microscopy (STM) [56], while carbon vacancies are responsible for an opening of the energy gap [57]. The increase in the density of states

• the ion mass, the aforementioned probability is lower for nitrogen than for argon. The energy required to displace a C atom from the hexagonal network was reported to be about 22 eV [87]. This allows for the creation of carbon vacancies that are subsequently filled by N atoms. It was shown that at

Defect formation in multiwalled carbon nanotubes under low-energy He and Ne ion irradiation

• Santhana Eswara,
• Jean-Nicolas Audinot,
• Brahime El Adib,
• Maël Guennou,
• Tom Wirtz and
• Patrick Philipp

Beilstein J. Nanotechnol. 2018, 9, 1951–1963, doi:10.3762/bjnano.9.186

• show that ion irradiation with incidence angles closer to the surface normal favours the formation of double and multiple vacancies and in-plane disorder while more grazing incidence leads mainly to single vacancies and substitution, the latter being limited to chemical species reacting with carbon [9

Multimodal noncontact atomic force microscopy and Kelvin probe force microscopy investigations of organolead tribromide perovskite single crystals

• Yann Almadori,
• David Moerman,
• Jaume Llacer Martinez,
• Philippe Leclère and
• Benjamin Grévin

Beilstein J. Nanotechnol. 2018, 9, 1695–1704, doi:10.3762/bjnano.9.161

• above, there is nowadays overwhelming evidence that hybrid perovskites should be treated (at least to some extent) as mixed electronic–ionic semiconductors [29]. Ion migration occurs in these materials due to the existence of anion and cation vacancies [30] and is already known to induce changes in the

Cr(VI) remediation from aqueous environment through modified-TiO₂-mediated photocatalytic reduction

• Rashmi Acharya,
• Brundabana Naik and
• Kulamani Parida

Beilstein J. Nanotechnol. 2018, 9, 1448–1470, doi:10.3762/bjnano.9.137

Understanding the performance and mechanism of Mg-containing oxides as support catalysts in the thermal dry reforming of methane

• Nor Fazila Khairudin,
• Mohd Farid Fahmi Sukri,
• Mehrnoush Khavarian and
• Abdul Rahman Mohamed

Beilstein J. Nanotechnol. 2018, 9, 1162–1183, doi:10.3762/bjnano.9.108

• . Therefore, the combination of Ce with Mg improves the catalyst basicity site. CeO2, commonly known for its oxygen storage capacity, contains a great concentration of highly mobile oxygen vacancies which could reduce the deposition of carbon on the catalyst surface [76]. In fact, CO2 molecules are more

• attracted to the base center (–Mg–OH group) and then dissociate on Ce2O3 via electron transfer to CO2 through oxygen vacancies to form CO2 and CeO2. Thus, the base center is most suitable for adsorbing the largest amount of CO2. The catalyst was stable for up to 50 h of reaction at 700 °C with an equal feed

Room-temperature single-photon emitters in titanium dioxide optical defects

• Kelvin Chung,
• Yu H. Leung,
• Chap H. To,
• Aleksandra B. Djurišić and
• Snjezana Tomljenovic-Hanic

Beilstein J. Nanotechnol. 2018, 9, 1085–1094, doi:10.3762/bjnano.9.100

• , rutile and brookite [34]. Defects can be introduced during fabrication or are intrinsic to the crystallographic structure. Extensive work on TiO2 surface defects [35] has come from the need to progress catalytic reactions. Point defects within the TiO2 include interstitials and vacancies [36][37][38

• surface defect sites [59] and surface oxygen vacancies on anatase nanocrystal films [60]. Similar photoluminescence in the red was also observed from ZnO defects [7][8][9]. The photodynamics of D1 was also recorded and can be seen for a pump power of 82 μW in Figure 4b. The time trace shows photostability

• attributed their visible emission to surface states originating from oxygen vacancies associated with Ti3+ ions. The work of Zhang et al. [42] on anatase nanocrystals fabricated through a chemical process could not conclude definitively the origin of their broad visible emission band centred around 578 nm

Cyclodextrin inhibits zinc corrosion by destabilizing point defect formation in the oxide layer

• Abdulrahman Altin,
• Maciej Krzywiecki,
• Adnan Sarfraz,
• Cigdem Toparli,
• Claudius Laska,
• Philipp Kerger,
• Aleksandar Zeradjanin,
• Karl J. J. Mayrhofer,
• Michael Rohwerder and
• Andreas Erbe

Beilstein J. Nanotechnol. 2018, 9, 936–944, doi:10.3762/bjnano.9.86

• an effect of the defect levels. The most probable defects are zinc vacancies VZn, as these have the lowest formation energy among the native point defects in ZnO [36][37]. VZn can be treated as deep acceptors, hence they should be manifested close to the top of the VB of ZnO [36][37]. A possible

• alternative explanation is a contribution from the β-CD HOMO to ZnO VBonset changes, since the β-CD HOMO onset was found 1.85 eV from the Fermi level. Intuitively, one would assume oxygen vacancies or zinc interstitials as dominating defects in the predominately n-type ZnO. The largest energy shift was

Effect of annealing treatments on CeO₂ grown on TiN and Si substrates by atomic layer deposition

• Silvia Vangelista,
• Rossella Piagge,
• Satu Ek and
• Alessio Lamperti

Beilstein J. Nanotechnol. 2018, 9, 890–899, doi:10.3762/bjnano.9.83

• equilibrium under standard conditions of temperature and pressure, stoichiometric CeO2 hosts Ce4+ and O2− ions in the cubic fluorite structure (space group Fm−3m in Pearson notation). However, Ce3+ ions can also be accommodated in the lattice structure in relation with oxygen vacancies, and Ce2O3 as minority

• growth and the oxygen vacancies, while preserving the cubic fluorite structure [12][13][14]. The electrical properties of CeO2 have been improved by performing post-deposition annealing at various temperatures [15]. In light of these previous studies, the interaction between substrate and annealing is

• atmosphere with the aim to passivate the film defects, namely the oxygen vacancies. A second set of samples has been annealed at high temperatures (600–900 °C) to induce full crystallization in CeO2 films and follow the corresponding structural and chemical changes induced by the annealing process

Surface-plasmon-enhanced ultraviolet emission of Au-decorated ZnO structures for gas sensing and photocatalytic devices

• T. Anh Thu Do,
• Truong Giang Ho,
• Thu Hoai Bui,
• Quang Ngan Pham,
• Hong Thai Giang,
• Thi Thu Do,
• Duc Van Nguyen and
• Dai Lam Tran

Beilstein J. Nanotechnol. 2018, 9, 771–779, doi:10.3762/bjnano.9.70

• factors, including absorbed oxygen species (O2−, O−, and O2−), charge carrier concentration, and the defects and vacancies on the ZnO surfaces. The gas response performance can be improved by a charge transfer process through surface modification [3][5][6] and doping of catalytic materials [7][8][9]. The

• emission band at 600 nm which was attributed to defects and vacancies [5][9][26][27][28]. After the Au NPs were decorated on the ZnO sub-micrometer spheres, one can see an enhanced band edge emission and a quenched visible emission. Interestingly, the UV–vis spectrum of plasmonic Au NPs overlaps with the

A review of carbon-based and non-carbon-based catalyst supports for the selective catalytic reduction of nitric oxide

• Shahreen Binti Izwan Anthonysamy,
• Syahidah Binti Afandi,
• Mehrnoush Khavarian and
• Abdul Rahman Bin Mohamed

Beilstein J. Nanotechnol. 2018, 9, 740–761, doi:10.3762/bjnano.9.68

• prepared using the sol–gel method had better catalytic activity than that of the impregnation method. Besides that, a huge amount of oxygen vacancies and superoxide ions was observed when cobalt metal was introduced via the sol–gel method, thereby enhancing the SCR performance. On the other hand, the co

Synthesis and characterization of two new TiO₂-containing benzothiazole-based imine composites for organic device applications

• Anna Różycka,
• Agnieszka Iwan,
• Krzysztof Artur Bogdanowicz,
• Michal Filapek,
• Natalia Górska,
• Damian Pociecha,
• Marek Malinowski,
• Patryk Fryń,
• Agnieszka Hreniak,
• Jakub Rysz,
• Paweł Dąbczyński and
• Monika Marzec

Beilstein J. Nanotechnol. 2018, 9, 721–739, doi:10.3762/bjnano.9.67

• both investigated imines. Similar interactions of oxygen vacancies existing on the TiO2 surface with SP1 and SP2 were observed. The imine:TiO2 mixtures showed good air stability and reusability, which demonstrates its potential for organic device applications. Keywords: azomethines; composites; HOMO

• hydrocarbon chains or aromatic rings are not visible. The observed changes confirmed the significant influence of titanium dioxide on the structural properties of both investigated compounds. It can be explained by the interactions of oxygen vacancies existing on the TiO2 surface with SP1 as well as SP2

Dynamics and fragmentation mechanism of (C₅H₄CH₃)Pt(CH₃)₃ on SiO₂ surfaces

• Kaliappan Muthukumar,
• Harald O. Jeschke and
• Roser Valentí

Beilstein J. Nanotechnol. 2018, 9, 711–720, doi:10.3762/bjnano.9.66

• ca. 15 Å in the original supercell) and an enhanced concentration of surface hydroxyl vacancies is provided in the reduced cell on partially dehydroxylated surfaces (i.e., 25% and 50% compared to 11% and 22%). However, the environment around these sites is similar (i.e., the sites are isolated on the

Mechanistic insights into plasmonic photocatalysts in utilizing visible light

• Kah Hon Leong,
• Azrina Abd Aziz,
• Lan Ching Sim,
• Pichiah Saravanan,
• Min Jang and
• Detlef Bahnemann

Beilstein J. Nanotechnol. 2018, 9, 628–648, doi:10.3762/bjnano.9.59

• the formation of copper vacancies in the material through exposure to oxygen or to a Ce(IV) complex [143]. Similarly, the LSPR band in stoichiometric Cu2–xS, Cu2–xSe and Cu2–xTe was improved by converting them into their nonstoichiometric counterparts via oxidation/reductive reactions [142]. Besides

Sensing behavior of flower-shaped MoS₂ nanoflakes: case study with methanol and xylene

• Maryam Barzegar,
• Masoud Berahman and
• Azam Iraji zad

Beilstein J. Nanotechnol. 2018, 9, 608–615, doi:10.3762/bjnano.9.57

• sulfur vacancies in the samples. The previous report shows that sulfur vacancies can increase the possibility of charge transfer in MoS2 nanoflakes which may act as the main reason to alter the conductivity [35]. It has been also reported that the crystal phase and edge play a significant role in the

• electro-activity of MoS2 nanosheets. Furthermore, sulfur vacancies contribute significantly to the electronic properties of MoS2 [36][37]. Hence, such sulfur vacancy is desirable for the gas sensing properties of MoS2. To study the application of the flower-shaped MoS2 for gas sensing, the Brunauer–Emmett

• the resistance returns back to its initial value. In the hydrothermal growth of MoS2 (as proven before), the high edges, corners and vacancies provide proper sites for reaction and sensing of the gas molecules [43]. A scrutinized investigation of the results revealed that when methanol enters the

Influence of the preparation method on the photocatalytic activity of Nd-modified TiO₂

• Patrycja Parnicka,
• Paweł Mazierski,
• Tomasz Grzyb,
• Wojciech Lisowski,
• Ewa Kowalska,
• Bunsho Ohtani,
• Adriana Zaleska-Medynska and
• Joanna Nadolna

Beilstein J. Nanotechnol. 2018, 9, 447–459, doi:10.3762/bjnano.9.43

• increasing the content of surface oxygen vacancies and defects [31][40]. These electron trapping sites can enhance the separation of photogenerated electron–hole pairs [24]. Furthermore, both pristine and Nd-TiO2 NPs exhibit obvious excitonic PL signals with a similar curve shape. The observed phenomena can

• amount of oxygen vacancies and defects was found on the surface of the 0.25% Nd-TiO2(HT) sample. As previously mentioned, the presence of oxygen deficient centres on the surface and surface defects such as Ti3+ can reduce the rate of electron–hole pair recombination [45][46][47]. Further, the light

Wafer-scale bioactive substrate patterning by chemical lift-off lithography

• Chong-You Chen,
• Chang-Ming Wang,
• Hsiang-Hua Li,
• Hong-Hseng Chan and
• Wei-Ssu Liao

Beilstein J. Nanotechnol. 2018, 9, 311–320, doi:10.3762/bjnano.9.31

• create distinct regions carrying dissimilar surface properties for a variety of applications [21]. With conformal contact-induced reactions, the top layer Au–Au bond breakage on an alkanethiol SAM covered Au substrate leads to the exposure of fresh Au toward the exterior environment. These vacancies can

Anchoring of a dye precursor on NiO(001) studied by non-contact atomic force microscopy

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

Beilstein J. Nanotechnol. 2018, 9, 242–249, doi:10.3762/bjnano.9.26

• nor any contrast inversion, as for example in measurements on TiO2 [51], and considering that Ni vacancies are supposed to occur more frequently in NiO [52], it can be assumed that the protrusions are related to oxygen atoms. This is also in agreement with earlier experimental studies on NiO where