Mo-doped boron nitride monolayer as a promising single-atom electrocatalyst for CO₂ conversion

• Qianyi Cui,
• Gangqiang Qin,
• Weihua Wang,
• Lixiang Sun,
• Aijun Du and
• Qiao Sun

Beilstein J. Nanotechnol. 2019, 10, 540–548, doi:10.3762/bjnano.10.55

• ), including Sc to Zn, Mo, Ru, Rh, Pd and Ag, supported on a boron nitride (BN) monolayer with boron vacancies, were investigated as electrocatalysts for the CO2 reduction reaction (CRR) using comprehensive density functional theory (DFT) calculations. The results demonstrate that a single-Mo-atom-doped boron

• refractory nature [11][35][36][37][38][39][40][41]. Moreover, BN nanomaterials have been used as superior substrates for doping various transition metals by electron beam irradiation [42] or solvent exfoliation [43] to form selected point defects, which are preferred to growing specific boron vacancies [42

Ceria/polymer nanocontainers for high-performance encapsulation of fluorophores

• Kartheek Katta,
• Dmitry Busko,
• Yuri Avlasevich,
• Katharina Landfester,
• Stanislav Baluschev and
• Rafael Muñoz-Espí

Beilstein J. Nanotechnol. 2019, 10, 522–530, doi:10.3762/bjnano.10.53

• combine biocompatibility with a high oxygen-scavenging ability. Cerium oxide is a lanthanide metal oxide with a redox potential behavior that can easily switch between cerium(IV) and cerium(III) and has the capability to leave oxygen vacancies in the crystal lattice [39]. Cerium(IV) oxide exhibits

• , which yielded the hybrid sample NC-CeO2. The fluorescence intensity is higher than for nanocapsules synthesized under ambient conditions without CeO2, but also even higher than for the sample NC(Ar) prepared under argon atmosphere. The oxygen vacancies present in the structure of cerium(IV) oxide

Sub-wavelength waveguide properties of 1D and surface-functionalized SnO₂ nanostructures of various morphologies

• Venkataramana Bonu,
• Binaya Kumar Sahu,
• Arindam Das,
• Sankarakumar Amirthapandian,
• Sandip Dhara and
• Harish C. Barshilia

Beilstein J. Nanotechnol. 2019, 10, 379–388, doi:10.3762/bjnano.10.37

• usual yellow-red luminescence (owing to bridging oxygen vacancies; OB) of the SnO2 is significantly suppressed and the luminescence appearing around the blue spectrum (owing to in-plane O vacancies; OP) becomes strong [13]. Interestingly, with surface functionalization, luminescence tuning is

• . Then, surface passivation takes place leading to suppression of the luminescence related to the OB vacancy sites. Moreover, luminescence from OP arises at high energy relative to the luminescence OB vacancies. We previously reported a detailed study on OTS functionalization of the SnO2 NPs [19]. It is

• 2.6 eV are assigned to band edge transitions. Earlier, it was shown from DFT calculations using an all-electron Gaussian approximation that formation of an acceptor state close to 1 eV above the valence band occurs due to the stable oxygen vacancies [31]. Thus, the above mentioned studies point out

Site-specific growth of oriented ZnO nanocrystal arrays

• Rekha Bai,
• Dinesh K. Pandya,
• Sujeet Chaudhary,
• Veer Dhaka,
• Vladislav Khayrudinov,
• Jori Lemettinen,
• Christoffer Kauppinen and
• Harri Lipsanen

Beilstein J. Nanotechnol. 2019, 10, 274–280, doi:10.3762/bjnano.10.26

• may in turn impact the physical properties on account of the known role of oxygen vacancies and defects on electron transport behavior of ZnO [26][27]. But in our case no such high temperature processing is required at any stage. Cho et al. [17] have used a solution method with tri-potassium citrate

Zn/F-doped tin oxide nanoparticles synthesized by laser pyrolysis: structural and optical properties

• Florian Dumitrache,
• Iuliana P. Morjan,
• Elena Dutu,
• Ion Morjan,
• Claudiu Teodor Fleaca,
• Monica Scarisoreanu,
• Alina Ilie,
• Marius Dumitru,
• Cristian Mihailescu,
• Adriana Smarandache and
• Gabriel Prodan

Beilstein J. Nanotechnol. 2019, 10, 9–21, doi:10.3762/bjnano.10.2

• SnO2 in its undoped form is an n-type semiconductor with a direct bandgap of 3.6 eV at room temperature. Its n-type conductivity is due to oxygen vacancies in its rutile structure. The bandgap, starting from the bulk value, increases as the size of the nanocrystal decreases, due to electron confinement

Nanostructure-induced performance degradation of WO₃·nH₂O for energy conversion and storage devices

• Zhenyin Hai,
• Mohammad Karbalaei Akbari,
• Zihan Wei,
• Danfeng Cui,
• Chenyang Xue,
• Hongyan Xu,
• Philippe M. Heynderickx,
• Francis Verpoort and
• Serge Zhuiykov

Beilstein J. Nanotechnol. 2018, 9, 2845–2854, doi:10.3762/bjnano.9.265

• samples originate from W5+ ions in the lattice, which reveals the formation of a few oxygen vacancies [29][46]. The O 1s spectra for all samples in Figure 5c depict two peaks with one main peak from the lattice oxygen, OL, and another from the oxygen in water molecules, OH2O [47][48]. With increasing

Graphene-enhanced metal oxide gas sensors at room temperature: a review

• Dongjin Sun,
• Yifan Luo,
• Marc Debliquy and
• Chao Zhang

Beilstein J. Nanotechnol. 2018, 9, 2832–2844, doi:10.3762/bjnano.9.264

• -sensing material. Therefore, further reduction of GO is necessary and the product after reduction is called reduced graphene oxide (rGO). Some oxygen functional groups remain after the reduction, some defects and vacancies are generated during the reduction, which are beneficial for the gas adsorption [13

• concentrations of NH3 and responded dramatically, which could be ascribed to the p–n heterojunctions formed between ZnO and rGO. However, the influence of humidity on the sensor response was not negligible due to the residual oxygen (high hydrophilicity) on rGO and the active sites (oxygen vacancies) on ZnO

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

• Bi = 148 pm and In = 142 pm atoms are very close. Therefore, in the InAs QD growth process on the GaAs1−xBix surface, In adatom surface diffusion can be realized both through substituting Ga or Bi vacancies. Increase of QD heights in the InAs/GaAs0.95Bi0.05 heterosystem is an indirect demonstration

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