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

Polystyrene-block-poly(ethylene oxide) copolymers as templates for stacked, spherical large-mesopore silica coatings: dependence of silica pore size on the PS/PEO ratio

• Roberto Nisticò,
• Giuliana Magnacca,
• Sushilkumar A. Jadhav and
• Dominique Scalarone

Beilstein J. Nanotechnol. 2016, 7, 1454–1460, doi:10.3762/bjnano.7.137

• narrow pore size distribution and high porosity have been obtained by a sol–gel reaction of a silicon oxide precursor (TEOS) and using polystyrene-block-poly(ethylene oxide) (PS-b-PEO) copolymers as templates in an acidic environment. PS-b-PEO copolymers with different molecular weight and composition

• ; mesoporous silica; soft templating; sol–gel; Introduction Mesoporous materials with large, tunable porosity are currently being investigated as selective molecular sieves, finding potential applications in many fields such as catalysis, encapsulation of proteins, filtration and separation of large molecules

• , membrane technology, drug delivery, dosing, adsorption, sensing, among many others [1][2][3][4][5]. Different approaches have been applied in order to obtain porous materials characterized by a controlled porous architecture. A sol–gel process, carried out in combination with a templating method and spin

Microwave synthesis of high-quality and uniform 4 nm ZnFe₂O₄ nanocrystals for application in energy storage and nanomagnetics

• Christian Suchomski,
• Ben Breitung,
• Ralf Witte,
• Michael Knapp,
• Sondes Bauer,
• Tilo Baumbach,
• Christian Reitz and
• Torsten Brezesinski

Beilstein J. Nanotechnol. 2016, 7, 1350–1360, doi:10.3762/bjnano.7.126

• narrow size distribution hold promise for many applications in different areas ranging from biomedicine to electronics and energy storage. Herein, the microwave-assisted sol–gel synthesis and thorough characterization of size-monodisperse zinc ferrite nanoparticles of spherical shape is reported. X-ray

• good material characteristics, it is remarkable that the microwave-based synthetic route is simple, easily reproducible and scalable. Keywords: 1-phenylethanol route; lithium-ion battery; nanomagnetism; nanoparticles; nonaqueous sol–gel synthesis; zinc ferrite; Introduction Spinel ferrites of the

• reported in the literature, including hydrothermal, mechanochemical and sol–gel routes (to name but a few) [15][16][17][18][19], and in particular solution-phase approaches seem promising with respect to exercising control over size and shape [20][21]. As an example, the preparation of uniform 4–8 nm

Influence of synthesis conditions on microstructure and phase transformations of annealed Sr₂FeMoO_6−x nanopowders formed by the citrate–gel method

• Marta Yarmolich,
• Nikolai Kalanda,
• Sergey Demyanov,
• Herman Terryn,
• Jon Ustarroz,
• Maksim Silibin and
• Gennadii Gorokh

Beilstein J. Nanotechnol. 2016, 7, 1202–1207, doi:10.3762/bjnano.7.111

• nm and a superstructural ordering of iron and molybdenum cations of 88%. Keywords: magnetic materials; microstructure; nanoparticles; phase transformation; sol–gel preparation; Introduction Due to their unique and extremely important magneto-transport and magnetic properties [1][2], metal oxide

• atmosphere with predetermined anionic and cationic defectiveness, is problematic [9]. This is due to several factors: the phase purity within the sample, cation and anion vacancies, sample microstructure, chemical composition and thickness of the grain boundaries [10][11][12][13]. Sol–gel technology is a

• relatively new, but very promising method to synthesize nanoscale, double perovskite materials at relatively low temperatures and in a shorter time [3][4][14]. However, despite numerous articles devoted to this subject [3][7][8][15][16], the optimization of a sol–gel-based synthesis procedure to obtain

Fast diffusion of silver in TiO₂ nanotube arrays

• Wanggang Zhang,
• Yiming Liu,
• Diaoyu Zhou,
• Hui Wang,
• Wei Liang and
• Fuqian Yang

Beilstein J. Nanotechnol. 2016, 7, 1129–1140, doi:10.3762/bjnano.7.105

• -dimensional structures. To increase the electric performance of TiO2, TiO2-based materials have been developed by incorporating metal nanoparticles in TiO2 nanotube arrays, using electrochemical deposition [21], irradiation of microwave [22], reduction [23], and sol–gel process [24], which involve the use of

Photocurrent generation in carbon nanotube/cubic-phase HfO₂ nanoparticle hybrid nanocomposites

• Protima Rauwel,
• Augustinas Galeckas,
• Martin Salumaa,
• Frédérique Ducroquet and
• Erwan Rauwel

Beilstein J. Nanotechnol. 2016, 7, 1075–1085, doi:10.3762/bjnano.7.101

• dimensionality of nanoparticles; among established methods ensuring control of both size and shape is the nonaqueous sol–gel route [18][19]. In our previous studies, a strong photoluminescence in the visible range was observed from HfO2 nanoparticles under below-bandgap excitation [20][21] and attributed to

• reaction by-products typical of nonaqueous sol–gel routes using precursors that do not contain hydrate species. Here, the amine species capping acts not only as a surfactant but also as a shape and size controlling agent during growth of the NP. Since our MWCNTs were not acid treated, the particles are

Selective photocatalytic reduction of CO₂ to methanol in CuO-loaded NaTaO₃ nanocubes in isopropanol

• Tianyu Xiang,
• Feng Xin,
• Jingshuai Chen,
• Yuwen Wang,
• Xiaohong Yin and
• Xiao Shao

Beilstein J. Nanotechnol. 2016, 7, 776–783, doi:10.3762/bjnano.7.69

• activity. Jeffrey C. S. Wu et al. [18] prepared NiO-loaded InTaO4 photocatalysts by a sol–gel method and carried out the photocatalytic reduction of CO2 in a self-made optical fiber reactor filled with 0.2 mol/L NaOH solution. The formation rate of methanol was 11.1 μmol/(g·h) under halogen lamp

Microwave solvothermal synthesis and characterization of manganese-doped ZnO nanoparticles

• Jacek Wojnarowicz,
• Roman Mukhovskyi,
• Elzbieta Pietrzykowska,
• Sylwia Kusnieruk,
• Jan Mizeracki and
• Witold Lojkowski

Beilstein J. Nanotechnol. 2016, 7, 721–732, doi:10.3762/bjnano.7.64

• ], combustion [52], sol–gel [7][31][33][53][54], spin coating [19][20], pulsed laser deposition [26], reactions in the solid state [35][55], thermal evaporation [56], and thermal evaporation vapour-phase deposition [30]. However, two of the most promising methods, which are still being developed are

Bacteriorhodopsin–ZnO hybrid as a potential sensing element for low-temperature detection of ethanol vapour

• Saurav Kumar,
• Sudeshna Bagchi,
• Senthil Prasad,
• Anupma Sharma,
• Ritesh Kumar,
• Rishemjit Kaur,
• Jagvir Singh and
• Amol P. Bhondekar

Beilstein J. Nanotechnol. 2016, 7, 501–510, doi:10.3762/bjnano.7.44

• in 2-propanol reduced with monoethanolamine) was prepared using the sol–gel method and was spin-coated, layer-by-layer, to form the ZnO-TF. Further, the ZnO-TF was annealed (400 °C) for an hour in order to obtain a uniform size distribution of the ZnO grains [34]. The resulting average thickness and

Evaluation of gas-sensing properties of ZnO nanostructures electrochemically doped with Au nanophases

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

Beilstein J. Nanotechnol. 2016, 7, 22–31, doi:10.3762/bjnano.7.3

• stabilized gold nanoparticles (Au NPs) directly on the surface of nanostructured ZnO powders, previously synthesized through a sol–gel process. The effect of thermal annealing temperatures (300 and 550 °C) on chemical, morphological, and structural properties of pristine and Au-doped ZnO nancomposites (Au

• and time-consuming; furthermore, metal nanoparticles prepared in these way can undergo undesired clustering, thus lowering their catalytic activity [41]. In this contribution, sol–gel pre-synthesized and dried ZnO powder was directly functionalized with Au NPs of controlled size and loading by means

• Sol–gel synthesis of ZnO ZnO nanostructures were prepared through a sol–gel process. An aqueous solution of ZnCl2 (0.1 M) was heated to 60 °C for 1 h in a water-bath under continuous stirring. Ammonia solution (0.1 M) was then added drop-wise until a dense gel was formed at pH 9 [43]. The gel was

A single-source precursor route to anisotropic halogen-doped zinc oxide particles as a promising candidate for new transparent conducting oxide materials

• Daniela Lehr,
• Markus R. Wagner,
• Johanna Flock,
• Julian S. Reparaz,
• Clivia M. Sotomayor Torres,
• Alexander Klaiber,
• Thomas Dekorsy and
• Sebastian Polarz

Beilstein J. Nanotechnol. 2015, 6, 2161–2172, doi:10.3762/bjnano.6.222

• routes in the liquid phase are commonly applied [35][36][37]. Whereas, bottom-up techniques such as the sol–gel process for metal oxides [38][39] work perfectly for the generation of an entire zoo of nanostructures, to realize at the same time intentional doping of those nanostructures is extremely

• not reactive enough, or they contain irremovable water, which leads to an undesired reaction of the heterocubane precursor to ZnO via sol–gel chemistry [66][67]. Elemental fluorine and anhydrous HF have not been tested yet, because of security issues handling these compounds. Materials synthesis and

Selective porous gates made from colloidal silica nanoparticles

• Roberto Nisticò,
• Paola Avetta,
• Paola Calza,
• Debora Fabbri,
• Giuliana Magnacca and
• Dominique Scalarone

Beilstein J. Nanotechnol. 2015, 6, 2105–2112, doi:10.3762/bjnano.6.215

• were prepared by spin-coating deposition of colloidal silica nanoparticles on an appropriate macroporous substrate. Silica nanoparticles very homogenous in size were obtained by sol–gel reaction of a metal oxide silica precursor, tetraethyl orthosilicate (TEOS), and using polystyrene-block-poly

• were obtained, suggesting possible applications of these nanoporous films as selective gates for controlled transport of chemical species in solution. Keywords: block copolymers; coatings; colloidal nanoparticles; silica; sol–gel synthesis; Introduction The development of smart nanoporous devices for

• hexagonally ordered pores were also employed as substrate for MCM-48 silica films, giving promising results [4][23][24]. The sol–gel polymerization process is a key procedure for the bottom-up synthesis of nano- and mesoporous silica films and in the literature there are several reviews focusing on this field

Effect of SiN_x diffusion barrier thickness on the structural properties and photocatalytic activity of TiO₂ films obtained by sol–gel dip coating and reactive magnetron sputtering

• Mohamed Nawfal Ghazzal,
• Eric Aubry,
• Nouari Chaoui and
• Didier Robert

Beilstein J. Nanotechnol. 2015, 6, 2039–2045, doi:10.3762/bjnano.6.207

• effect of the thickness of the silicon nitride (SiNx) diffusion barrier on the structural and photocatalytic efficiency of TiO2 films obtained with different processes. We show that the structural and photocatalytic efficiency of TiO2 films produced using soft chemistry (sol–gel) and physical methods

• (reactive sputtering) are affected differentially by the intercalating SiNx diffusion barrier. Increasing the thickness of the SiNx diffusion barrier induced a gradual decrease of the crystallite size of TiO2 films obtained by the sol–gel process. However, TiO2 obtained using the reactive sputtering method

• films obtained by each process was discussed. Keywords: diffusion barrier; photocatalysis; reactive sputtering; SiNx; sol–gel; titanium dioxide film; TiO2; Introduction Titanium dioxide thin films in active phase (mostly anatase) have been widely studied due to their ability to produce strong oxidant

Paramagnetism of cobalt-doped ZnO nanoparticles obtained by microwave solvothermal synthesis

• Jacek Wojnarowicz,
• Sylwia Kusnieruk,
• Tadeusz Chudoba,
• Stanislaw Gierlotka,
• Witold Lojkowski,
• Wojciech Knoff,
• Malgorzata I. Lukasiewicz,
• Bartlomiej S. Witkowski,
• Anna Wolska,
• Marcin T. Klepka,
• Tomasz Story and
• Marek Godlewski

Beilstein J. Nanotechnol. 2015, 6, 1957–1969, doi:10.3762/bjnano.6.200

• applied techniques include: solvothermal [34][35], hydrothermal [36][37], sol–gel [38][39] among others. These techniques enabled the control of the size and morphology of the particles by setting appropriate conditions, for instance, synthesis temperature, time, and the concentration of precursors. For

• ferromagnetic and paramagnetic properties [46][47]. Using hydrothermal [32][48] and sol–gel [49][50] synthesis methods, Co-doped ZnO with both ferromagnetic and paramagnetic properties was obtained [39][41][42]. These observations questioned the possibility of producing powders with controllable properties

Radiation losses in the microwave K_u band in magneto-electric nanocomposites

• Talwinder Kaur,
• Sachin Kumar,
• Jyoti Sharma and
• A. K. Srivastava

Beilstein J. Nanotechnol. 2015, 6, 1700–1707, doi:10.3762/bjnano.6.173

• ) and vector network analyser (VNA). Experimental Synthesis The synthesis of La–Co-substituted barium hexaferrite has been carried out through a sol–gel method [19] using metal nitrates (AR grade chemicals) without any purification. Aqueous solutions of iron and metal salts are mixed with each other in

Peptide-equipped tobacco mosaic virus templates for selective and controllable biomineral deposition

• Klara Altintoprak,
• Axel Seidenstücker,
• Alexander Welle,
• Sabine Eiben,
• Petia Atanasova,
• Nina Stitz,
• Alfred Plettl,
• Joachim Bill,
• Hartmut Gliemann,
• Holger Jeske,
• Dirk Rothenstein,
• Fania Geiger and
• Christina Wege

Beilstein J. Nanotechnol. 2015, 6, 1399–1412, doi:10.3762/bjnano.6.145

• silica nucleation in the absence of additional peptide domains. Generally, it still remains a challenge to predictably, selectively and uniformly coat individual nanotemplate particles with silica. For this purpose, sol–gel condensation from precursors in alcoholic solutions seems most viable according

• KD10 to induce local silicification are in line with these earlier observations. This illustrates the beneficial effect of amino acid-based charge relay on a spatially directed TEOS conversion. Silica precipitation by sol–gel reaction from precursor solutions is likely to involve a gradual growth of

• in guiding the deposition of silica sheaths from TEOS precursor solutions around the viral soft-matter cores. The peptide KD10 designed in this study on the basis of earlier tests [61] allowed for the most selective and controllable silicification by sol–gel condensation. This was likely due to its

Synthesis, characterization and in vitro effects of 7 nm alloyed silver–gold nanoparticles

• Simon Ristig,
• Svitlana Chernousova,
• Wolfgang Meyer-Zaika and
• Matthias Epple

Beilstein J. Nanotechnol. 2015, 6, 1212–1220, doi:10.3762/bjnano.6.124

• wet chemical syntheses by co-reduction of gold and silver salts with citrate [18][19], NaBH4 [20] or starch and glucose [21], reduction with hydrazine in water-in-oil emulsions [22], sol–gel processes [23] or UV irradiation [24]. Recently, the generation of alloyed silver–gold nanoparticles by laser

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

• , they can be used in many applications, such as gas sensors [4]. A wide range of techniques to deposit thin films are used, such as molecular beam epitaxy (MBE) [5], single-source chemical vapor deposition (SS CVD) [6], metalorganic chemical vapor deposition (MOCVD) [7], sol–gel [8], spray pyrolysis [9