Morphology-controlled synthesis and a comparative study of the physical properties of SnO2 nanostructures: from ultrathin nanowires to ultrawide nanobelts

A Review on 1-D Nanomaterials: Scaling-Up with Gas-Phase Synthesis

Nanowire-like materials exhibit distinctive properties comprising optical polarisation, waveguiding, and hydrophobic channelling, amongst many other useful phenomena. Such 1-D derived anisotropy can be further enhanced by arranging many similar nanowires into a coherent matrix, known as an array superstructure. Manufacture of nanowire arrays can be scaled-up considerably through judicious use of gas-phase methods. Historically, the gas-phase approach however has been extensively used for the bulk and rapid synthesis of isotropic 0-D nanomaterials such as carbon black and silica. The primary goal of this review is to document recent developments, applications, and capabilities in gas-phase synthesis methods of nanowire arrays. Secondly, we elucidate the design and use of the gas-phase synthesis approach; and finally, remaining challenges and needs are addressed to advance this field.

Tin oxide based nanostructured materials: synthesis and potential applications

In view of their inimitable characteristics and properties, SnO₂ nanomaterials and nanocomposites have been used not only in the field of diverse advanced catalytic technologies and sensors but also in the field of energy storage such as lithium-ion batteries and supercapacitors, and in the field of energy production such as solar cells and water splitting. This review discusses the various synthesis techniques such as traditional methods, including processes like thermal decomposition, chemical vapor deposition, electrospinning, sol-gel, hydrothermal, solvothermal, and template-mediated methods and green methods, which include synthesis through plant-mediated, microbe-mediated, and biomolecule-mediated processes. Moreover, the advantages and limitations of these synthesis procedures and how to overcome them that would lead to future research are also discussed. This literature also focuses on various applications such as environmental remediation, energy production, energy storage, and removal of biological contaminants. Therefore, the rise and journey of SnO₂-based nanocomposites will motivate the modern generation of chemists to modify and design robust nanoparticles and nanocomposites that can effectively tackle significant environmental challenges. This overview concludes by providing future perspectives on research into tin oxide in synthesis and its various applications.

Recent insights into SnO2-based engineered nanoparticles for sustainable H2 generation and remediation of pesticides

Due to the ongoing industrial revolution and global health pandemics, solar-driven water splitting and pesticide degradation are highly sought to cope with catastrophes such as depleting fossil reservoirs, global warming, and environmental degradation.

Bimetallic organic framework-derived SnO2/Co3O4 heterojunctions for highly sensitive acetone sensors

Excellent gas-sensing performance of SnO2/Co3O4 is attributed to the synergistic effect of catalysis of Co3+ and the formation of p–n heterojunctions.

An olive-shaped SnO2 nanocrystal-based low concentration H2S gas sensor with high sensitivity and selectivity

Olive-shaped SnO₂ nanocrystals were synthesized successfully via a facile hydrothermal route, using tin dichloride hydrate, oxalic acid dihydrate and polyvinylpyrrolidone as reaction precursors, and showed great potential in the large-scale preparation of SnO₂ nanocrystals.

Pulsed laser-deposited MoS₂ thin films on W and Si: field emission and photoresponse studies

We report field electron emission investigations on pulsed laser-deposited molybdenum disulfide (MoS2) thin films on W-tip and Si substrates. In both cases, under the chosen growth conditions, the dry process of pulsed laser deposition (PLD) is seen to render a dense nanostructured morphology of MoS2, which is important for local electric field enhancement in field emission application. In the case of the MoS2 film on silicon (Si), the turn-on field required to draw an emission current density of 10 μA/cm(2) is found to be 2.8 V/μm. Interestingly, the MoS2 film on a tungsten (W) tip emitter delivers a large emission current density of ∼30 mA/cm(2) at a relatively lower applied voltage of ∼3.8 kV. Thus, the PLD-MoS2 can be utilized for various field emission-based applications. We also report our results of photodiode-like behavior in (n- and p- type) Si/PLD-MoS2 heterostructures. Finally we show that MoS2 films deposited on flexible kapton substrate show a good photoresponse and recovery. Our investigations thus hold great promise for the development of PLD MoS2 films in application domains such as field emitters and heterostructures for novel nanoelectronic devices.

Nanoscale semiconductor-insulator-metal core/shell heterostructures: facile synthesis and light emission

Controllably constructing hierarchical nanostructures with distinct components and designed architectures is an important theme of research in nanoscience, entailing novel but reliable approaches of bottom-up synthesis. Here, we report a facile method to reproducibly create semiconductor-insulator-metal core/shell nanostructures, which involves first coating uniform MgO shells onto metal oxide nanostructures in solution and then decorating them with Au nanoparticles. The semiconductor nanowire core can be almost any material and, herein, ZnO, SnO(2) and In(2)O(3) are used as examples. We also show that linear chains of short ZnO nanorods embedded in MgO nanotubes and porous MgO nanotubes can be obtained by taking advantage of the reduced thermal stability of the ZnO core. Furthermore, after MgO shell-coating and the appropriate annealing treatment, the intensity of the ZnO near-band-edge UV emission becomes much stronger, showing a 25-fold enhancement. The intensity ratio of the UV/visible emission can be increased further by decorating the surface of the ZnO/MgO nanowires with high-density plasmonic Au nanoparticles. These heterostructured semiconductor-insulator-metal nanowires with tailored morphologies and enhanced functionalities have great potential for use as nanoscale building blocks in photonic and electronic applications.

UV light emitting transparent conducting tin-doped indium oxide (ITO) nanowires

Multifunctional single crystalline tin-doped indium oxide (ITO) nanowires with tuned Sn doping levels are synthesized via a vapor transport method. The Sn concentration in the nanowires can reach 6.4 at.% at a synthesis temperature of 840 °C, significantly exceeding the Sn solubility in ITO bulks grown at comparable temperatures, which we attribute to the unique feature of the vapor-liquid-solid growth. As a promising transparent conducting oxide nanomaterial, layers of these ITO nanowires exhibit a sheet resistance as low as 6.4 Ω/[Symbol: see text] and measurements on individual nanowires give a resistivity of 2.4 × 10(-4) Ω cm with an electron density up to 2.6 × 10(20) cm(-3), while the optical transmittance in the visible regime can reach ∼ 80%. Under the ultraviolet excitation the ITO nanowire samples emit blue light, which can be ascribed to transitions related to defect levels. Furthermore, a room temperature ultraviolet light emission is observed in these ITO nanowires for the first time, and the exciton-related radiative process is identified by using temperature-dependent photoluminescence measurements.

Tin oxide nanorod array-based electrochemical hydrogen peroxide biosensor

SnO2 nanorod array grown directly on alloy substrate has been employed as the working electrode of H2O2 biosensor. Single-crystalline SnO2 nanorods provide not only low isoelectric point and enough void spaces for facile horseradish peroxidase (HRP) immobilization but also numerous conductive channels for electron transport to and from current collector; thus, leading to direct electrochemistry of HRP. The nanorod array-based biosensor demonstrates high H2O2 sensing performance in terms of excellent sensitivity (379 μA mM-1 cm-2), low detection limit (0.2 μM) and high selectivity with the apparent Michaelis-Menten constant estimated to be as small as 33.9 μM. Our work further demonstrates the advantages of ordered array architecture in electrochemical device application and sheds light on the construction of other high-performance enzymatic biosensors.

One-dimensional SnO(2) nanostructures: facile morphology tuning and lithium storage properties

This paper presents a facile method of preparation whereby one-dimensional SnO(2) nanostructures of different morphologies, namely nanotubes, nanotube-nanorod hybrids and nanorods, could be obtained by thermally treating an alumina template loaded with SnCl(4) aqueous solution in air. The fraction of interior cavity could be tuned by varying the precursor concentration in the preparation. The fully tubular nanostructure was found to be the most suitable for reversible Li(+) storage. Out of an initially large capacity of 976 mA h g(-1), 654 mA h g(-1) could still be retained after 40 cycles of charge and discharge.

Synthesis of Tin Nitride Sn(x)N(y) Nanowires by Chemical Vapour Deposition

Tin nitride (Sn(x)N(y)) nanowires have been grown for the first time by chemical vapour deposition on n-type Si(111) and in particular by nitridation of Sn containing NH(4)Cl at 450 degrees C under a steady flow of NH(3). The Sn(x)N(y) nanowires have an average diameter of 200 nm and lengths >/=5 mum and were grown on Si(111) coated with a few nm's of Au. Nitridation of Sn alone, under a flow of NH(3) is not effective and leads to the deposition of Sn droplets on the Au/Si(111) surface which impedes one-dimensional growth over a wide temperature range i.e. 300-800 degrees C. This was overcome by the addition of ammonium chloride (NH(4)Cl) which undergoes sublimation at 338 degrees C thereby releasing NH(3) and HCl which act as dispersants thereby enhancing the vapour pressure of Sn and the one-dimensional growth of Sn(x)N(y) nanowires. In addition to the action of dispersion, Sn reacts with HCl giving SnCl(2) which in turn reacts with NH(3) leading to the formation of Sn(x)N(y) NWs. A first estimate of the band-gap of the Sn(x)N(y) nanowires grown on Si(111) was obtained from optical reflection measurements and found to be approximately 2.6 eV. Finally, intricate assemblies of nanowires were also obtained at lower growth temperatures.