A top-down approach for fabricating three-dimensional closed hollow nanostructures with permeable thin metal walls

• Carlos Angulo Barrios and
• Víctor Canalejas-Tejero

Beilstein J. Nanotechnol. 2017, 8, 1231–1237, doi:10.3762/bjnano.8.124

• as artificial cells [2], controlled transport and delivery of chemical agents (e.g., pharmaceutical drugs) [3], catalysis [4], lithium batteries [5] and confined reaction compartments (nanoreactors) [1]. Most fabrication methods of nanocages are based on bottom-up techniques, mainly colloidal and sol

• –gel chemical reactions [1][2][3][4][5]. These procedures allow the synthesis of disperse, hollow nanostructures with precise control of their physical and chemical properties, such as size, shape, material composition and structural characteristics of the shell (thickness, permeability and surface

Preparation of thick silica coatings on carbon fibers with fine-structured silica nanotubes induced by a self-assembly process

• Benjamin Baumgärtner,
• Hendrik Möller,
• Thomas Neumann and
• Dirk Volkmer

Beilstein J. Nanotechnol. 2017, 8, 1145–1155, doi:10.3762/bjnano.8.116

• carbon fibers with a silica shell is presented in this work. By immobilizing linear polyamines on the carbon fiber surface, the high catalytic activity of polyamines in the sol–gel-processing of silica precursors is used to deposit a silica coating directly on the fiber’s surface. The surface

• fiber by fibrillar and interconnected silica fine-structures. The high surface area of the nanostructured composite fiber may be exploited for catalytic applications and adsorption purposes. Keywords: biomimetic silicification; carbon fiber; self-assembly; silica nanotubes; sol–gel process

• –gel techniques [6]. Even though the CVD method leads typically to a uniform and dense surface coating, low deposition rates can make this process time-consuming and expensive. The sol–gel method is advantageous owing to the low processing temperature, inexpensive and commercially available precursors

Assembly of metallic nanoparticle arrays on glass via nanoimprinting and thin-film dewetting

• Sun-Kyu Lee,
• Sori Hwang,
• Yoon-Kee Kim and
• Yong-Jun Oh

Beilstein J. Nanotechnol. 2017, 8, 1049–1055, doi:10.3762/bjnano.8.106

• noble metal nanoparticles on glass substrates via nanoimprinting and dewetting of metallic thin films. Glass templates were made via pattern transfer from a topographic Si mold to an inorganically cross-linked sol–gel (IGSG) resist on glass using a two-layer polydimethylsiloxane (PDMS) stamp followed by

• metallic thin films at high temperatures. Hybrid sol–gel thin films prepared from methyltriethoxysilane (MTEOS) may fulfill these requirements due to the complete hydrolyzation of the ethoxy groups and decomposition of the methyl groups [16][17]. MTEOS films have attracted attention as self-sustainable

• 184 PDMS. In the next imprinting step, an inorganically cross-linked sol–gel (ICSG) resist with a thickness (tf) of 400 nm was spin-coated on a Pyrex glass substrate. To improve the wettability of the resist, the glass surface was pretreated with a dielectric barrier discharge (DBD) using He and O2

High photocatalytic activity of Fe₂O₃/TiO₂ nanocomposites prepared by photodeposition for degradation of 2,4-dichlorophenoxyacetic acid

• Shu Chin Lee,
• Hendrik O. Lintang and
• Leny Yuliati

Beilstein J. Nanotechnol. 2017, 8, 915–926, doi:10.3762/bjnano.8.93

• ][15]. Commonly, the reported methods for the preparation of Fe2O3/TiO2 include impregnation [5][6][16][17][18], sol–gel [7][19], and hydrothermal methods [8][9][10]. A combination of several processes has also been employed, such as the electrospinning method combined with a hydrothermal approach [11

• the Fe(III) complex at 400 °C [5]. This is in contrast to the one prepared by the sol–gel method that showed an obviously reduced Eg value as the Fe ions were incorporated into the TiO2 lattice [7][19]. Diffuse reflectance (DR) UV–vis spectra and Tauc plots of the nanocomposites prepared by the

First examples of organosilica-based ionogels: synthesis and electrochemical behavior

• Andreas Taubert,
• Ruben Löbbicke,
• Barbara Kirchner and
• Fabrice Leroux

Beilstein J. Nanotechnol. 2017, 8, 736–751, doi:10.3762/bjnano.8.77

• . Experimental Preparation of the organosilica monoliths. Silica monoliths were made via sol–gel reaction from bis(3-(trimethoxysilyl)propyl)amine (BTMSPA) and tetramethylorthosilicate (TMOS) or methyltrimethoxysilane (MTMS). Reactions were made such that the total silicon concentration in the reaction mixture

• remain intact. The monoliths synthesized in methanol are clear to translucent as long as they are wet, but turn opaque upon drying. The monoliths grown in acetone are opaque already after the sol–gel reaction and Soxhlet extraction. Transmission electron microscopy (TEM, Figure 2) images obtained from

Synthesis of graphene–transition metal oxide hybrid nanoparticles and their application in various fields

• Arpita Jana,
• Elke Scheer and
• Sebastian Polarz

Beilstein J. Nanotechnol. 2017, 8, 688–714, doi:10.3762/bjnano.8.74

• thermochromic transition at 257 °C and this material is used as a catalyst for industrial processes, gas sensors and in LIBs [105]. Various nanostructures of V2O5 such as nanotubes, nanowires, nanofibers, nanobelts, and nanorods have been prepared by sol–gel processes, hydrothermal processes [106

• 3D flower hybrids [113], where this typical morphology results in a high surface area as well as better electrical contact with the graphene leading to better electrochemical performance. Liu et al. have developed a sol–gel method for the incorporation of GSs into V2O5 nanoribbons [114]. These

Carbon nanotube-wrapped Fe₂O₃ anode with improved performance for lithium-ion batteries

• Guoliang Gao,
• Yan Jin,
• Qun Zeng,
• Deyu Wang and
• Cai Shen

Beilstein J. Nanotechnol. 2017, 8, 649–656, doi:10.3762/bjnano.8.69

• sol–gel method to prepare graphene-wrapped Fe2O3, which demonstrated an excellent capacity retention of 777 mAh·g−1 at a current density of 100 mA·g−1 after 30 cycles. Wang et al. [29] synthesized Fe2O3/GCNTs via a hydrothermal synthesis method and subsequent thermal reduction. The synthesized Fe2O3

Investigation of the photocatalytic efficiency of tantalum alkoxy carboxylate-derived Ta₂O₅ nanoparticles in rhodamine B removal

• Subia Ambreen,
• Mohammad Danish,
• Narendra D. Pandey and
• Ashutosh Pandey

Beilstein J. Nanotechnol. 2017, 8, 604–613, doi:10.3762/bjnano.8.65

• Subia Ambreen Mohammad Danish Narendra D. Pandey Ashutosh Pandey Department of Chemistry, Motilal Nehru National Institute of Technology, Allahabad, 211004, India 10.3762/bjnano.8.65 Abstract Ta2O5 nanoparticles have been synthesized from alkoxy carboxylates of tantalum via the sol–gel route

• . Tantalum alkoxides were reacted with chlorocarboxylic acids in order to lower the susceptibility hydrolysis. When these modified alkoxy carboxylates were used in the sol–gel synthesis, they yielded Ta2O5 nanoparticles of better properties than those of the alkoxide-derived Ta2O5 nanoparticles. These

• absorption of these materials [9][10][11]. Tantalum(V) alkoxides are important precursors for materials based on tantalum oxide in sol–gel processes. The reactions involved in sol–gel processes can be written as: An inorganic network is formed during hydrolysis the ends of which are occupied either by –OH

Thin SnO_x films for surface plasmon resonance enhanced ellipsometric gas sensing (SPREE)

• Daniel Fischer,
• Andreas Hertwig,
• Uwe Beck,
• Volkmar Lohse,
• Detlef Negendank,
• Martin Kormunda and
• Norbert Esser

Beilstein J. Nanotechnol. 2017, 8, 522–529, doi:10.3762/bjnano.8.56

• , several different coating methods were developed which include chemical vapor deposition [11], sol–gel [12], spray pyrolysis [13], sputtering [14][15][16] and electron beam evaporation [17]. In our approach, we aim to develop a new sensing concept which combines the adsorption concept of MOS sensors with

Fiber optic sensors based on hybrid phenyl-silica xerogel films to detect n-hexane: determination of the isosteric enthalpy of adsorption

• Jesús C. Echeverría,
• Ignacio Calleja,
• Paula Moriones and
• Julián J. Garrido

Beilstein J. Nanotechnol. 2017, 8, 475–484, doi:10.3762/bjnano.8.51

• , respectively. The films were synthesized by the sol–gel method and affixed to the end of optical fibers by the dip-coating technique. Fourier transform infrared spectroscopy, N2 adsorption–desorption at 77 K and X-ray diffraction analysis were used to characterize the xerogels. At a given pressure of n-hexane

• ]. Some advantages of FOCSs over electrical methods are immunity to electromagnetic interference and safety while working with flammable and explosive compounds. Although the xerogel films prepared by the sol–gel method are often considered chemically inert, the films and analytes can interact by one or

• more mechanisms, such as electrostatic, hydrophobic or hydrogen bonding. Films made of hybrid silica materials synthesized by the sol–gel process are well suited for the preparation of sensing elements. These films have chemical and thermal stability, transparency over a wide wavelength range

The longstanding challenge of the nanocrystallization of 1,3,5-trinitroperhydro-1,3,5-triazine (RDX)

• Florent Pessina and
• Denis Spitzer

Beilstein J. Nanotechnol. 2017, 8, 452–466, doi:10.3762/bjnano.8.49

• diameter of 70 to 100 nm. However, the nanoparticles produced from this elegant solution exhibit an undesired rod-like morphology. Sol–gel Energetic materials processed by the sol–gel method are desensitized by being embedded in a matrix, usually a silica one. Developed by Gash et al. [23] and Tillotson et

• nanocomposites using a technique similar to sol–gel [30]. The matrix is the NC itself solidified by micrometer-sized AP crystals and cross-linked with toluene diisocyanate (TDI) and dibutyltin dilaurate (DBTDL), whereas RDX is dissolved in acetone inside that template. The gel and the crystallization of RDX is

Tailoring bifunctional hybrid organic–inorganic nanoadsorbents by the choice of functional layer composition probed by adsorption of Cu²⁺ ions

• Veronika V. Tomina,
• Inna V. Melnyk,
• Yuriy L. Zub,
• Aivaras Kareiva,
• Miroslava Vaclavikova,
• Gulaim A. Seisenbaeva and
• Vadim G. Kessler

Beilstein J. Nanotechnol. 2017, 8, 334–347, doi:10.3762/bjnano.8.36

• was optimized controlling the synthesis conditions, such as concentrations of reactants, basicity of the medium, and the process temperature. Keywords: copper(II) ions; methyl groups; N- and F-containing functional groups; silica nanospheres; sol–gel processes; sorption; surface chemistry

Functionalized TiO₂ nanoparticles by single-step hydrothermal synthesis: the role of the silane coupling agents

• Antoine R. M. Dalod,
• Lars Henriksen,
• Tor Grande and
• Mari-Ann Einarsrud

Beilstein J. Nanotechnol. 2017, 8, 304–312, doi:10.3762/bjnano.8.33

• a dark red powder was obtained for 4-tert-butylcatechol and dopamine surface functionalized samples, respectively. More recently, Gao and Cui reported a sol–gel method in which TiO2 nanoparticles functionalized with chlorinated alcohols through hydrogen bonding were produced [21]. However, sol–gel

• synthesis often leads to poorly crystalline particles [22]. Hydrothermal synthesis [23] is simple and cost efficient [24] and allows for improved crystallinity compared to sol–gel methods [22] giving improved TiO2 characteristics for applications such as photocatalysis and solar cell applications [2][25][26

Template-controlled piezoactivity of ZnO thin films grown via a bioinspired approach

• Nina J. Blumenstein,
• Fabian Streb,
• Stefan Walheim,
• Thomas Schimmel,
• Zaklina Burghard and
• Joachim Bill

Beilstein J. Nanotechnol. 2017, 8, 296–303, doi:10.3762/bjnano.8.32

• high mechanical deformation [13]. Growth of such oriented films was achieved via technically sophisticated methods under harsh reaction conditions [14][15][16][17]. For example radio-frequency magnetron sputtering [14][17], pulsed laser deposition [16] or sol–gel methods followed by annealing [15] were

• the films due to their (002) texture. This also reflects in the value obtained for deff of 3.2 pm V−1 (d33 = 6.4 pm V−1). This value is in the range or higher than the one of other oriented, ZnO thin films prepared by RF magnetron sputtering (2–13 pm V−1) [14] or sol–gel process (5 pm V−1) [15]. Since

Photocatalysis applications of some hybrid polymeric composites incorporating TiO₂ nanoparticles and their combinations with SiO₂/Fe₂O₃

• Andreea Laura Chibac,
• Tinca Buruiana,
• Violeta Melinte and
• Emil C. Buruiana

Beilstein J. Nanotechnol. 2017, 8, 272–286, doi:10.3762/bjnano.8.30

• physicochemical characterization of nanoparticles Titania nanoparticles (TiO2) and titania nanoparticles mixed with Si–O–Si (TiO2/SiO2), γ-Fe2O3 (TiO2/Fe2O3) or Si–O–Si and γ-Fe2O3 (TiO2/SiO2/Fe2O3) were obtained by the sol–gel method, using titanium isopropoxide as precursor. The crystalline structures of the

• further purification. Nanoparticles preparation Synthesis of nanocrystalline TiO2 For the preparation of TiO2 nanoparticles through the sol–gel method, a literature pathway was employed [49], keeping the molar ratio of TTIP, glacial acetic acid and water at 1:10:350. Thus, 9.3 mL (31.5 mmol) TTIP were

Nanocrystalline ZrO₂ and Pt-doped ZrO₂ catalysts for low-temperature CO oxidation

• Amit Singhania and
• Shipra Mital Gupta

Beilstein J. Nanotechnol. 2017, 8, 264–271, doi:10.3762/bjnano.8.29

• nanoparticles such as sol–gel [21], precipitation [22], combustion [23], hydrothermal synthesis [24], solvothermal synthesis [25], reverse micelles [26], chemical vapor synthesis [27], aerosol pyrolysis [28], and sonochemical synthesis [29]. Dongare et al. [30] described the synthesis of ZrO2 by a sol–gel

Sensitive detection of hydrocarbon gases using electrochemically Pd-modified ZnO chemiresistors

• Elena Dilonardo,
• Michele Penza,
• Marco Alvisi,
• Gennaro Cassano,
• Cinzia Di Franco,
• Francesco Palmisano,
• Luisa Torsi and
• Nicola Cioffi

Beilstein J. Nanotechnol. 2017, 8, 82–90, doi:10.3762/bjnano.8.9

• ], directly deposited on the surface of sol–gel pre-synthesized ZnO nanostructures. Further post-annealing at 550 °C to obtain ZnO NRs is necessary [45]. The prepared hybrid Pd@ZnO nanostructures are proposed as active layer in chemiresistive gas sensors for the detection of pollutant HCs. The effect of the

• contrary, high selectivity towards NO2 gas detection was obtained by using pristine ZnO chemiresistors. Experimental Sol–gel synthesis of ZnO ZnO nanostructures were prepared via a sol–gel process following the procedure reported in [45]. The subsequent washing of the obtained gel led to the complete

Fundamental properties of high-quality carbon nanofoam: from low to high density

• Natalie Frese,
• Shelby Taylor Mitchell,
• Christof Neumann,
• Amanda Bowers,
• Armin Gölzhäuser and
• Klaus Sattler

Beilstein J. Nanotechnol. 2016, 7, 2065–2073, doi:10.3762/bjnano.7.197

• nanowires have been produced [9]. A few studies of semiconductor and insulator nanofoams have also been reported. A sol–gel process was used to produce silicon nanofoam and acousto-optic characteristics were probed [10]. Silica nanofoam was used as a support material for highly active single- and dual-site

Nanostructured SnO₂–ZnO composite gas sensors for selective detection of carbon monoxide

• Paul Chesler,
• Cristian Hornoiu,
• Susana Mihaiu,
• Cristina Vladut,
• Jose Maria Calderon Moreno,
• Mihai Anastasescu,
• Carmen Moldovan,
• Bogdan Firtat,
• Costin Brasoveanu,
• George Muscalu,
• Ion Stan and
• Mariuca Gartner

Beilstein J. Nanotechnol. 2016, 7, 2045–2056, doi:10.3762/bjnano.7.195

• prepared and deposited on a miniaturized porous alumina transducer using the sol–gel and dip coating method. The transducer, developed by our research group, contains Au interdigital electrodes on one side and a Pt heater on the other side. The sensing films were characterized using SEM and AFM techniques

• compared to its response to CO2, CH4, and C3H8, thus the sensor is considered to be selective for CO under these test conditions. Keywords: composite thin film sensor; dip coating; low detection limit; miniaturized alumina transducer; selective CO detection; sol–gel; Introduction For the past decade, the

• ., screen printing) or complicated wet preparation routes that require the use of special solvents and templates [23]. Usually the sol–gel technique combined in our case with dip coating is a low temperature process; it requires less energy consumption and causes less pollution – all features that make it

Organoclay hybrid materials as precursors of porous ZnO/silica-clay heterostructures for photocatalytic applications

• Marwa Akkari,
• Pilar Aranda,
• Abdessalem Ben Haj Amara and
• Eduardo Ruiz-Hitzky

Beilstein J. Nanotechnol. 2016, 7, 1971–1982, doi:10.3762/bjnano.7.188

• the organic–inorganic interface [17]. In general, this sol–gel procedure leads to heterostructured clay-based materials with enhanced textural properties compared to the ones of pristine silicates [14]. The simultaneous use of silicon and metal-alkoxide precursors gives rise, for instance, to the

• . Tetramethoxyorthosilicate (TMOS) from Fluka (>98 %) was used here as silica precursor. Sample preparations ZnO (NP) synthesis was achieved as reported by Akkari et al. [22]. In a first step, SiO2-clay organo-heterostructures (Figure 1) were synthesized by a heterocoagulation reaction involving a sol–gel process with the

• ). This suspension was stirred at 50 °C to homogenize the system and then stoichiometric amounts of water and isopropanol (H2O/isopropanol/TMOS 4:2:1 molar ratio) is added to start the hydrolysis of TMOS. After the sol–gel transition the system was dried overnight at 50 °C. The final ZnO/SiO2-clay

Functionalized platinum nanoparticles with surface charge trigged by pH: synthesis, characterization and stability studies

• Giovanna Testa,
• Laura Fontana,
• Iole Venditti and
• Ilaria Fratoddi

Beilstein J. Nanotechnol. 2016, 7, 1822–1828, doi:10.3762/bjnano.7.175

• solvothermal techniques are well favored for the synthesis of PtNPs, together with sol–gel methods [17]. They give rise to colloidal suspensions although a fine control of the size, dispersity and the surface functionalization is quite difficult to reach. Poly(N-vinyl-2-pyrrolidone) (PVP) has been used as a

In situ formation of reduced graphene oxide structures in ceria by combined sol–gel and solvothermal processing

• Jingxia Yang,
• Johannes Ofner,
• Bernhard Lendl and
• Ulrich Schubert

Beilstein J. Nanotechnol. 2016, 7, 1815–1821, doi:10.3762/bjnano.7.174

• –gel processing, by which the rGO structures and the catalytic activity were enhanced. Keywords: ceria; CO oxidation; graphene oxide; sol–gel processing; Introduction Ceria (CeO2) has been widely studied as catalyst or catalyst support for redox reactions owing to its high oxygen storage and release

• -synthesized ceria particles followed by reduction to reduced graphene oxide (rGO) [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16]. In a previous study, we have synthesized CeO2 [17] from cerium tert-butoxide by combined sol–gel and solvothermal processing. The kind of post-synthesis treatment of the

• , varying proportions of pre-synthesized graphene oxide (GO) were introduced into the ceria gel to investigate its dispersion and its effect on structure and properties of the sol–gel ceria. Raman spectra showed that the D-bands of all rGO–CeO2 composites were shifted to lower values (Figure 1), indicating

Nanostructured TiO₂-based gas sensors with enhanced sensitivity to reducing gases

• Wojciech Maziarz,
• Anna Kusior and
• Anita Trenczek-Zajac

Beilstein J. Nanotechnol. 2016, 7, 1718–1726, doi:10.3762/bjnano.7.164

• stoichiometry of the oxygen-to-titanium content ratio play a major role in the electrical properties of TiO2 [17]. Different ways in which TiO2 can be prepared include sol–gel process [18][19][20], flame spray synthesis [21], hydrothermal process [22], electrospinning methods [23], chemical and physical vapor

Influence of hydrothermal synthesis parameters on the properties of hydroxyapatite nanoparticles

• Sylwia Kuśnieruk,
• Jacek Wojnarowicz,
• Agnieszka Chodara,
• Tadeusz Chudoba,
• Stanislaw Gierlotka and
• Witold Lojkowski

Beilstein J. Nanotechnol. 2016, 7, 1586–1601, doi:10.3762/bjnano.7.153

• chemistry techniques, such as direct precipitation from aqueous solutions, electrochemical deposition [23], sol–gel processes [24] and hydrothermal synthesis [25][26][27] (Table 1). In the majority of cases, the synthesized powder is a stoichiometric hydroxyapatite, and oftentimes contains additional phases

Nanostructured germanium deposited on heated substrates with enhanced photoelectric properties

• Ionel Stavarache,
• Valentin Adrian Maraloiu,
• Petronela Prepelita and
• Gheorghe Iordache

Beilstein J. Nanotechnol. 2016, 7, 1492–1500, doi:10.3762/bjnano.7.142

• [18] and biosensors [19]. To produce high-quality Ge particles packed into different matrices, various approaches are reported in scientific papers such as pulsed laser deposition [20][21], sol–gel [22], evaporation under vacuum [23], chemical vapor deposition [24], microwave-assisted heating [25