High photocatalytic activity of V-doped SrTiO₃ porous nanofibers produced from a combined electrospinning and thermal diffusion process

• Panpan Jing,
• Wei Lan,
• Qing Su and
• Erqing Xie

Beilstein J. Nanotechnol. 2015, 6, 1281–1286, doi:10.3762/bjnano.6.132

• above room temperature in air, generally, the oxygen vacancy is one of the most important defects that can be easily introduced [31]. The crystal cell is then distorted and the cell volume or lattice constant is reduced. However, if a few Ti4+ ions are substituted by V5+ ions, some oxygen vacancies will

Characterization of nanostructured ZnO thin films deposited through vacuum evaporation

• Jose Alberto Alvarado,
• Arturo Maldonado,
• Héctor Juarez,
• Mauricio Pacio and
• Rene Perez

Beilstein J. Nanotechnol. 2015, 6, 971–975, doi:10.3762/bjnano.6.100

• region) corresponds to oxygen vacancies (VO). The emission intensities are similar intensity for the thin films annealed at 400 and 25 °C. They change drastically when we have the nanostructures deposited as thin film where the main emission line attributed to VZn is related to the form of the

Transformation of hydrogen titanate nanoribbons to TiO₂ nanoribbons and the influence of the transformation strategies on the photocatalytic performance

• Melita Rutar,
• Nejc Rozman,
• Matej Pregelj,
• Carla Bittencourt,
• Romana Cerc Korošec,
• Andrijana Sever Škapin,
• Aleš Mrzel,
• Srečo D. Škapin and
• Polona Umek

Beilstein J. Nanotechnol. 2015, 6, 831–844, doi:10.3762/bjnano.6.86

• ., TO-580, TN-400 and TN-580, both resonances that were observed at room temperature (Figure 8) increase, i.e., the number of oxygen vacancies and the Ti3+ ions increases. Moreover, the former are most likely responsible also for the resonances appearing at g values [35][41] of approx. 2.012, and approx

• within the band-gap states created by substitutional and interstitional N-doping [23][36] and to creation of an additional localized state due to oxygen vacancies below the conduction band [36]. Assessment of the photocatalytic performance of the TiO2 NRs The photocatalytic performance (PP) of the

• were required to decompose the iPrOH. In our case this is reflected in lower k1 values [44]. The calcination of the TiO2 in an ammonia atmosphere increases the amount of oxygen vacancies and Ti3+, which is in agreement with the EPR results (Figure 8 and Figure 9). The oxygen vacancies act as

Tm-doped TiO₂ and Tm₂Ti₂O₇ pyrochlore nanoparticles: enhancing the photocatalytic activity of rutile with a pyrochlore phase

• Desiré M. De los Santos,
• Javier Navas,
• Teresa Aguilar,
• Antonio Sánchez-Coronilla,
• Concha Fernández-Lorenzo,
• Rodrigo Alcántara,
• Jose Carlos Piñero,
• Ginesa Blanco and
• Joaquín Martín-Calleja

Beilstein J. Nanotechnol. 2015, 6, 605–616, doi:10.3762/bjnano.6.62

• , respectively, confirming the presence of Tm(III) in an oxide matrix. Thus, considering that the predominant cations in the TiO2 lattice of the doped samples are Ti4+ and Tm3+, and that the doping is substitutional, oxygen vacancies are generated to maintain the local neutrality of the lattice. The presence of

• oxygen vacancies is interesting for photocatalytic applications because, for example, an increase in oxygen vacancies generates more surface defects on the synthesized nanoparticles. This can be studied from the O 1s XPS spectra. Figure 2c (bottom) shows the different contributions in the O 1s spectrum

• demonstrates how the amount of O in the adsorbed species increases with the Tm concentration. This is due to the increase in oxygen vacancies produced, and thus in the number of adsorption centers available. The adsorption of hydroxy groups onto the surface is of interest in photocatalytic applications

Novel ZnO:Ag nanocomposites induce significant oxidative stress in human fibroblast malignant melanoma (Ht144) cells

• Syeda Arooj,
• Samina Nazir,
• Akhtar Nadhman,
• Nafees Ahmad,
• Bakhtiar Muhammad,
• Ishaq Ahmad,
• Kehkashan Mazhar and
• Rashda Abbasi

Beilstein J. Nanotechnol. 2015, 6, 570–582, doi:10.3762/bjnano.6.59

• possible presence of the ZnO2 structure. The minor variation in oxygen amount is, however, due to oxygen vacancies created by the Fermi gas we used in our annealing procedure. These oxygen vacancies gradually obtained some atmospheric oxygen when samples were stored under normal atmospheric conditions. The

Tunable white light emission by variation of composition and defects of electrospun Al₂O₃–SiO₂ nanofibers

• Jinyuan Zhou,
• Gengzhi Sun,
• Hao Zhao,
• Xiaojun Pan,
• Zhenxing Zhang,
• Yujun Fu,
• Yanzhe Mao and
• Erqing Xie

Beilstein J. Nanotechnol. 2015, 6, 313–320, doi:10.3762/bjnano.6.29

• -like heterostructure composed of SiOx particles orderly embedded in the highly crystalline α-Al2O3 nanoribbons. They observed a strong and stable blue emission centered at 467 nm under excitation at 320 nm, which was attributed to the neutral oxygen vacancies (≡Si–Si≡) in the SiOx–Al2O3 heterostructure

Morphology, structural properties and reducibility of size-selected CeO_2−x nanoparticle films

• Maria Chiara Spadaro,
• Sergio D’Addato,
• Gabriele Gasperi,
• Francesco Benedetti,
• Paola Luches,
• Vincenzo Grillo,
• Giovanni Bertoni and
• Sergio Valeri

Beilstein J. Nanotechnol. 2015, 6, 60–67, doi:10.3762/bjnano.6.7

• electrostatic force. With the assumption that the increase of the lattice parameter is also due to a higher concentration of oxygen vacancies, Tsunekawa results are complementary with the ones of Zhou et al. [7], obtained for NP diameters between 4 and 60 nm. These results led to the conclusion that the lattice

• parameter increase is related to the formation of oxygen vacancies and Ce3+ ions. Following this approach, Deshpande et al. [8] correlated the lattice parameter expansion with the concentration of Ce3+ ions (measured by X-ray photoelectron spectroscopy, XPS), ascribing it to the higher ionic radius of Ce3

• +, compared to the Ce4+, and to the introduction of oxygen vacancies, which in turn induces a distortion of the local symmetry. In the last years a ‘Madelung model’ has been proposed to describe the properties of ionic crystals as a function of their surface to volume ratio. Here, the balance between long

Manganese oxide phases and morphologies: A study on calcination temperature and atmospheric dependence

• Matthias Augustin,
• Daniela Fenske,
• Ingo Bardenhagen,
• Anne Westphal,
• Martin Knipper,
• Thorsten Plaggenborg,
• Joanna Kolny-Olesiak and
• Jürgen Parisi

Beilstein J. Nanotechnol. 2015, 6, 47–59, doi:10.3762/bjnano.6.6

• especially useful for application as molecular sieves and absorbents for the removal of toxic species from waste gases such as carbon monoxide and nitrogen oxide [6][7][8]. Additionally, manganese oxide structures exhibiting oxygen vacancies provide additional active sites for reduction and oxidation

• crystallite sizes of less than a third compared to those obtained in O2. Furthermore, the lattice constants of Mn3O4 produced in Ar are smaller at all temperatures than those obtained by calcination in O2 atmosphere. This could be due to oxygen vacancies, as the oxygen for the oxidation to Mn3O4 in pure Ar is

• only supplied by the manganese glycolate precursor and cannot be obtained from the gas atmosphere. The presence of oxygen vacancies is also supported by the less pronounced variation of the lattice constants of Mn3O4 obtained at 320 °C and 350 °C in O2 atmospheres, leading to the assumption of

Silicon and germanium nanocrystals: properties and characterization

• Ivana Capan,
• Alexandra Carvalho and
• José Coutinho

Beilstein J. Nanotechnol. 2014, 5, 1787–1794, doi:10.3762/bjnano.5.189

• by varying the implantation conditions (implantation energy and dose) and subsequent annealing. It is a well-known fact that Si ion implantation of SiO2 is characterized by the production of a large number of oxygen vacancies and other defects in the oxide matrix. These defects enhance the QD

Effects of palladium on the optical and hydrogen sensing characteristics of Pd-doped ZnO nanoparticles

• Anh-Thu Thi Do,
• Hong Thai Giang,
• Thu Thi Do,
• Ngan Quang Pham and
• Giang Truong Ho

Beilstein J. Nanotechnol. 2014, 5, 1261–1267, doi:10.3762/bjnano.5.140

• interstitials, Zn anti-site vacancies, and oxygen vacancies, it is of interest to find out whether Pd incorporated in ZnO significantly improves sensitivity and specificity for hydrogen [13][14]. In this work, we have successfully synthesized Pd-doped ZnO nanoparticles for an application as gas sensors by a low

Electron-beam induced deposition and autocatalytic decomposition of Co(CO)₃NO

• Florian Vollnhals,
• Martin Drost,
• Fan Tu,
• Esther Carrasco,
• Andreas Späth,
• Rainer H. Fink,
• Hans-Peter Steinrück and
• Hubertus Marbach

Beilstein J. Nanotechnol. 2014, 5, 1175–1185, doi:10.3762/bjnano.5.129

• subsequently exposed to Co(CO)3NO. The investigated surfaces were SiOx layers on Si(100) and Si3N4, both of which are suitable substrates for EBISA using Fe(CO)5 [7][16]. On these surfaces, electron stimulated desorption of oxygen and the thereby created oxygen vacancies were identified as the active sites for

Mesoporous cerium oxide nanospheres for the visible-light driven photocatalytic degradation of dyes

• Subas K. Muduli,
• Songling Wang,
• Shi Chen,
• Chin Fan Ng,
• Cheng Hon Alfred Huan,
• Tze Chien Sum and
• Han Sen Soo

Beilstein J. Nanotechnol. 2014, 5, 517–523, doi:10.3762/bjnano.5.60

• , and solar thermal dissociation of water and CO2 [14][15][16][17][18]. Cerium oxides with oxygen vacancies represent an underexplored area of nanotechnology with the potential to provide visible-light absorbing photocatalysts [13][19][20][21]. Cerium is relatively earth-abundant and the oxides

• Polycrystalline Ce7O12 samples have been previously synthesized, but harsh conditions (up to 1030 °C) by reduction of CeO2 with CO were employed [25][26]. Instead, mild, surfactant-free solvothermal conditions were used to prepare mesoporous cerium oxide with oxygen vacancies. A solution of ceric ammonium nitrate

• P25 TiO2 nanomaterials. The estimated band gap from the Tauc plot is approximately 2.7 eV (Figure 2b), which corresponds to an absorption edge in the blue region (460 nm). The reduced band gap compared to CeO2 can be attributed to the presence of oxygen vacancies, as previously reported [32]. The

Encapsulation of nanoparticles into single-crystal ZnO nanorods and microrods

• Jinzhang Liu,
• Marco Notarianni,
• Llew Rintoul and
• Nunzio Motta

Beilstein J. Nanotechnol. 2014, 5, 485–493, doi:10.3762/bjnano.5.56

• –matter interaction within those crystals, the luminescence of the cavity material has been conventionally used as a light source. Under excitation, ZnO emits UV light at about 380 nm ascribed to its wide band gap (Eg ≈ 3.4 eV). With crystal defects such as oxygen vacancies, ZnO show visible

Structural, optical and photocatalytic properties of flower-like ZnO nanostructures prepared by a facile wet chemical method

• Sini Kuriakose,
• Neha Bhardwaj,
• Jaspal Singh,
• Biswarup Satpati and
• Satyabrata Mohapatra

Beilstein J. Nanotechnol. 2013, 4, 763–770, doi:10.3762/bjnano.4.87

• have shown that the surface morphology of the ZnO nanostructures plays a very important role in the photocatalytic activity [17][19][20][21][43]. Differences mainly originate from differences in surface area, polar planes or oxygen vacancies. The processes underlying the photocatalytic degradation of

Modulation of defect-mediated energy transfer from ZnO nanoparticles for the photocatalytic degradation of bilirubin

• Tanujjal Bora,
• Karthik K. Lakshman,
• Soumik Sarkar,
• Abhinandan Makhal,
• Samim Sardar,
• Samir K. Pal and
• Joydeep Dutta

Beilstein J. Nanotechnol. 2013, 4, 714–725, doi:10.3762/bjnano.4.81

• of the heme catabolism that can cause jaundice when its excretion is impaired. The photocatalytic degradation of BR activated by ZnO nanoparticles through a non-radiative energy transfer pathway can be influenced by the surface defect-states (mainly the oxygen vacancies) of the catalyst nanoparticles

• ]. It has been reported that the native defects in the ZnO lattice, mostly the oxygen vacancy sites, play an important role in the photocatalytic activity of the nanostructures [11]. Oxygen vacancies have been reported as the cause of the characteristic green luminescence of ZnO [12][13][14]. These

• vacancies exist in three charged states: singly charged (VO+), doubly charged (VO++) and neutral (VOx). The presence of the oxygen vacancies and other native defects in the ZnO lattice reduces the direct e−/h+ recombination process and thus increases the quantum yield of ZnO nanocrystalline photocatalysts

Evolution of microstructure and related optical properties of ZnO grown by atomic layer deposition

• Adib Abou Chaaya,
• Roman Viter,
• Mikhael Bechelany,
• Zanda Alute,
• Donats Erts,
• Anastasiya Zalesskaya,
• Kristaps Kovalevskis,
• Vincent Rouessac,
• Valentyn Smyntyna and
• Philippe Miele

Beilstein J. Nanotechnol. 2013, 4, 690–698, doi:10.3762/bjnano.4.78

• ]. Crystallinity and stochiometry of the film determine the concentration of point defects (zinc and oxygen vacancies, interstitial zinc and oxygen) [20]. The band gap of ZnO nanostructures decreases from 3.29 to 3.23 eV with an increase of the grain size [21]. The electrical conductivity of ZnO is affected by a

• ]. According to Wang et al. [18], emission bands at 1.9–2.0 eV of ZnO ALD ultrathin films are due to doubly ionized oxygen vacancies (V(O)++) [48]. The PL spectra correlate with the absorption spectra. Absorption spectra have tails and peaks in the 3.2–1.78 eV range matching the optical transitions defect

• interstitials at 2.21–2.25 eV identified in PL spectra of oxygen-rich samples correlate well with the EDX results. Doubly ionized oxygen vacancies show up in the PL spectra of all samples at 1.9–2.0 eV pointing to the active role of surface effects in the emission spectra. An increasing thickness during the

Characterization of electroforming-free titanium dioxide memristors

• John Paul Strachan,
• J. Joshua Yang,
• L. A. Montoro,
• C. A. Ospina,
• A. J. Ramirez,
• A. L. D. Kilcoyne,
• Gilberto Medeiros-Ribeiro and
• R. Stanley Williams

Beilstein J. Nanotechnol. 2013, 4, 467–473, doi:10.3762/bjnano.4.55

• , which can be considered an ordered array of oxygen vacancies in a TiO2 rutile phase, is a thermodynamically stable and metallic (at room temperature) Magnéli phase. In the unipolar switching mode [25], this conductive channel is created and destroyed during ON and OFF switching, respectively, and spans

• eV). While not as distinct as the heavily reduced phase found in the electroformed layer (Figure 3a, blue curve), the trend is the same, showing that indeed the as-grown film for forming-free devices contains a substantial concentration of reduced valence titanium atoms and therefore oxygen vacancies

Photoresponse from single upright-standing ZnO nanorods explored by photoconductive AFM

• Igor Beinik,
• Markus Kratzer,
• Astrid Wachauer,
• Lin Wang,
• Yuri P. Piryatinski,
• Gerhard Brauer,
• Xin Yi Chen,
• Yuk Fan Hsu,
• Aleksandra B. Djurišić and
• Christian Teichert

Beilstein J. Nanotechnol. 2013, 4, 208–217, doi:10.3762/bjnano.4.21

• properties is negligible. It has been shown recently that the phenomenon of persistent photoconductivity in ZnO can also be attributed to the presence of oxygen vacancies in the bulk [25]. Thus, more precise confirmation of the origin of this phenomenon is required and the characterization of single

• carriers from defect-localized states. The experimental findings are in good agreement with previous theoretical predictions based on density functional theory calculations [42] and will be discussed on the basis of the presence of oxygen vacancies. Experimental ZnO nanorods were grown by thermal

• commonly attributed to the presence of oxygen vacancies [17]. The crystalline quality can be estimated by a simple comparison of the intensities of the exciton peak and defect band. From the PL measurements we conclude that the generation of electron–hole pairs at room temperature becomes possible with a

Plasmonics-based detection of H₂ and CO: discrimination between reducing gases facilitated by material control

• Gnanaprakash Dharmalingam,
• Nicholas A. Joy,
• Benjamin Grisafe and
• Michael A. Carpenter

Beilstein J. Nanotechnol. 2012, 3, 712–721, doi:10.3762/bjnano.3.81

• overcoat has a crucial role in restricting the growth of the Au NPs during long-term high-temperature exposures, and its thickness has a direct impact on the number of oxygen vacancies in the film. The vacancies are introduced into the film through the yttria dopant in zirconia. YSZ is an excellent oxygen

• , and the number of oxygen vacancies that would be formed due to the yttria dopant level. Calculation of the number of oxygen vacancies per square centimeter led to the following numbers for the films: 8.16 × 1015/cm2 for the small-particle sample and the thinner gold sample, 2.04 × 1015/cm2 for the

• H2 adsorption, coupled with the smaller-diameter Au particles. Although the thinner Au sample has the same thickness of YSZ and hence essentially the same number of oxygen vacancies as the small-particle sample, the smaller Au particles in the latter case lead to an increased response. This may be

Paper modified with ZnO nanorods – antimicrobial studies

• Mayuree Jaisai,
• Sunandan Baruah and
• Joydeep Dutta

Beilstein J. Nanotechnol. 2012, 3, 684–691, doi:10.3762/bjnano.3.78

• offer large surface-to-volume ratios. Hydrothermally grown ZnO nanorods possess inherent defects in the form of oxygen vacancies and zinc interstitials, which shift its optical absorption from the ultraviolet to the visible region [20]. We previously reported the visible-light photocatalytic degradation

Functionalised zinc oxide nanowire gas sensors: Enhanced NO₂ gas sensor response by chemical modification of nanowire surfaces

• Eric R. Waclawik,
• Jin Chang,
• Andrea Ponzoni,
• Isabella Concina,
• Dario Zappa,
• Elisabetta Comini,
• Nunzio Motta,
• Guido Faglia and
• Giorgio Sberveglieri

Beilstein J. Nanotechnol. 2012, 3, 368–377, doi:10.3762/bjnano.3.43

• approach to the use of organic SAMs to enhance gas response is to use them to generate extra oxygen vacancies and defects in the MOx sensor surface. This has been successfully demonstrated previously for the case of a ZnO nanobelt oxygen gas sensor, by heating the sensor to temperatures at which desorption

Ultraviolet photodetection of flexible ZnO nanowire sheets in polydimethylsiloxane polymer

• Jinzhang Liu,
• Nunzio Motta and
• Soonil Lee

Beilstein J. Nanotechnol. 2012, 3, 353–359, doi:10.3762/bjnano.3.41

• expected. Oxygen vacancies and antisite oxygen give contributions to the green PL emission around 520 nm; zinc vacancies and interstitial oxygen contribute to the blue PL emission (450–470 nm) [17]. We made devices based on the strap-shaped nanowire sheets (width 2 mm). To make electrode contacts, silver

Investigation on structural, thermal, optical and sensing properties of meta-stable hexagonal MoO₃ nanocrystals of one dimensional structure

• Angamuthuraj Chithambararaj and
• Arumugam Chandra Bose

Beilstein J. Nanotechnol. 2011, 2, 585–592, doi:10.3762/bjnano.2.62

• counts/ppm for λmax = 684, 764 and 935 nm, respectively. From the plot, the maximum sensitivity is seen for λmax = 684 nm. Here, it is proposed that the gas sensing mechanism follows the changes in the refractive index and evanescent wave absorption. For h-MoO3, the oxygen vacancies and interstitial

Defects in oxide surfaces studied by atomic force and scanning tunneling microscopy

• Thomas König,
• Georg H. Simon,
• Lars Heinke,
• Leonid Lichtenstein and
• Markus Heyde

Beilstein J. Nanotechnol. 2011, 2, 1–14, doi:10.3762/bjnano.2.1

• single point defects or single adsorbates, instead of integrating over a square millimeter range. However, absolute values of the work function cannot be measured directly, only work function differences. Point defects Oxygen vacancies, also known as color centers, are electron trapping point defects and

Enhanced visible light photocatalysis through fast crystallization of zinc oxide nanorods

• Sunandan Baruah,
• Mohammad Abbas Mahmood,
• Myo Tay Zar Myint,
• Tanujjal Bora and
• Joydeep Dutta

Beilstein J. Nanotechnol. 2010, 1, 14–20, doi:10.3762/bjnano.1.3

• Abstract Hydrothermally grown ZnO nanorods have inherent crystalline defects primarily due to oxygen vacancies that enhance optical absorption in the visible spectrum, opening up possibilities for visible light photocatalysis. Comparison of photocatalytic activity of ZnO nanorods and nanoparticle films on