Tin-doped Indium Oxide Nanowires Research Articles

Facile in-situ synthesis of MnO2-ITO NWs composite for electrochemical supercapacitors

MnO2 is a promising material for pseudocapacitor applications due to its high specific capacity and low cost, while MnO2 electrodes suffer from their low electrical and ionic conductivities. Herein, a facile and low-cost method is adopted to synthesize MnO2 - tin-doped indium oxide nanowires (ITO NWs) composite with highly ordered network structures for electrochemical supercapacitors. Such network structure can effectively decrease the ion diffusion and charge transport resistance in the electrode. The specific capacitance of bare ITO NWs is only 2.83 F g−1, thus the contribution of the matrix material to capacitance can be ignored, and the optimized MnO2 possesses a high specific capacitor of 508.54 F g−1 at the scan rate of 5 mV s−1. It is anticipated that the synthesized MnO2-ITO NWs composite will find wide applications in supercapacitors (SCs) and other devices in virtue of their outstanding characters of good conductivity, convenient synthesis.

Facile fabrication of NiO foam@Sn-doped In2O3 nanowire heterosturctures for highly sensitive ethylene glycol gas sensors at low temperatures

Ethylene glycol is odorless and harmful to human beings. However, the high operating temperature and the low gas response of the ethylene glycol sensors limit their wide applications. Herein, p-type nickel oxide foam/ n-type tin-doped indium oxide nanowires composite (NTO) has been fabricated for ethylene glycol gas sensing. The NTO composite was prepared by complete oxidation of Ni foam at high temperature, then Sn-doped indium oxide (ITO) nanowires were grown on NiO foam by chemical vapor deposition. The assembled NTO sensor exhibits a unique response (Rg/Ra=160.72) to 100 ppm ethylene glycol at a low temperature of 125 ℃, and a fast response/ recovery time (8.7 s/ 19.3 s). This excellent gas-sensitive performance of NTO sensors can be attributed to the formation of p/n heterojunctions and the In and Sn doping of NiO during ITO growth. This fabrication method provides an effective strategy for building NiO-based heterostructures for high-performance gas sensors.

Horizontally Grown Tin-doped Indium-Oxide Nanowires

Horizontally Grown Tin-doped Indium-Oxide Nanowires

Growth evolution of self-catalytic tin-doped indium oxide nanowires

Self-catalytic tin-doped indium oxide nanowires were prepared via thermal-chemical vapor deposition. The growth evolution of these nanowires with respect to the growth time was investigated. Furthermore, the effect of oxygen gas flow on the growth was determined by comparing nanowires grown with/without the flow. In the early growth stages, the nanowires crawled to the substrate after droplet formation. Based on the Ellingham diagram and the difference between the energy barriers, Sn remained in the liquid phase on the head of the nanowires, whereas In2O3 formed as the stem of the wires. After 30 s of growth, the head of the crawling nanowires separated from the substrate, regardless of the droplet size. The droplets were almost completely eliminated from the end of the ITO nanowires grown under the oxygen gas flow but were present at the tips of the wires grown without the flow. The ITO nanowires grown under the flow were characterized by a turn-on field and field enhancement factor of ∼3.4 V/μm and 1632, respectively. The present work provides the mechanism for the growth of nanowires and the design architecture of materials used in various applications.

Controlled synthesis of polystyrene-assisted tin-doped indium oxide nanowire networks

Abstract

Designing Three-Dimensional Nanowire Arrays As Efficient Counter Electrodes for Quantum-Dot-Sensitized Solar Cells

Quantum-dot-sensitized solar cell (QDSSC) has been considered as an alternative to new generation photovoltaics, but it still presents very low conversion efficiency. Besides the continuous effort on improving photoanodes and electrolytes, the focused investigation on charge transfer at interfaces and rational design for counter electrodes are recently receiving much attention. Rationally designing nanostructures aiming at solving the critical issues on counter electrodes would be possible to shed light on how to break through the conversion efficiency record of QDSSCs and push this field to move forward. In this presentation, the effort in this group on designing new nanostructures as efficient counter electrodes for QDSSCs will be discussed. For example, tunnel junction arrays configured with degenerate n-type tin-doped indium oxide nanowire (ITO) core and degenerate p-type Cu2S nanocrystal shell (ITO@Cu2S) was designed and fabricated as new efficient counter electrode for QDSSCs. ITO nanowire array core provided a three dimensional conductive network. ITO core and Cu2S nanocrystal shell formed effective tunnel junctions with carrier transport path shorter than 100 nm. It was found that sheet resistance (Rh) was not only dependent on the electron conductivity of the substrate but also related to the semiconductor-electrode interface between CTO and catalysts. The high-quality tunnel junctions resulted in the considerable decrease in Rh of the device, and facilitated electron transfer from CTO to Cu2S. Moreover, the chemical inert nature of ITO made this type of counter electrode stable in liquid electrolyte with no intrinsic issue like copper dissolution in state-of-the-art Cu/Cu2S counter electrode. Compared with planar structures, the three-dimensional nanowire arrays presented higher surface area and easy accessibility of electrolyte, leading to higher catalytic activity of counter electrode as evidenced by apparently decreased charge transfer resistance. As a result, the power conversion efficiency of QDSSCs with the designed ITO@Cu2S nanowire counter electrodes increased by 84.5% and 33.5% compared to that with Au and Cu2S counter electrodes, respectively.[1] Furthermore, the influence of the interface of ITO/Cu2S on the conversion efficiency of QDSSCs was further investigated by using different synthetic route and the following post-treatment to fabricate the ITO@Cu2S nanowire counter electrodes.[2] More interestingly, the hierarchical ITO@Cu2S nanowire arrays were further fabricated and found to be able to further reduce the sheet resistance and charge transfer resistance between the electrolyte and the counter electrode. As a result, the QDSSCs with smaller series resistance, larger shunt resistance and thus the power conversion efficiency of over 6% has been achieved by using this kind of hierarchical ITO@Cu2S nanowire arrays as counter electrodes.[3] Finally, by combining a newly-developed high quality ∼4 nm Cd-, Pb-free Zn-Cu-In-Se alloyed QDs and a new three-dimensional counter electrode, we have achieved QDSSCs with a record certified efficiency of 11.6%.

Epitaxy-enabled vapor-liquid-solid growth of tin-doped indium oxide nanowires with controlled orientations.

Controlling the morphology of nanowires in bottom-up synthesis and assembling them on planar substrates is of tremendous importance for device applications in electronics, photonics, sensing and energy conversion. To date, however, there remain challenges in reliably achieving these goals of orientation-controlled nanowire synthesis and assembly. Here we report that growth of planar, vertical and randomly oriented tin-doped indium oxide (ITO) nanowires can be realized on yttria-stabilized zirconia (YSZ) substrates via the epitaxy-assisted vapor-liquid-solid (VLS) mechanism, by simply regulating the growth conditions, in particular the growth temperature. This robust control on nanowire orientation is facilitated by the small lattice mismatch of 1.6% between ITO and YSZ. Further control of the orientation, symmetry and shape of the nanowires can be achieved by using YSZ substrates with (110) and (111), in addition to (100) surfaces. Based on these insights, we succeed in growing regular arrays of planar ITO nanowires from patterned catalyst nanoparticles. Overall, our discovery of unprecedented orientation control in ITO nanowires advances the general VLS synthesis, providing a robust epitaxy-based approach toward rational synthesis of nanowires.

Preparation and electrical properties of electrospun tin-doped indium oxide nanowires

Well-aligned tin-doped indium (ITO) nanowires have been prepared using the electrospinningprocess. The Sn doping mechanism and microstructure have been characterized byx-ray diffraction (XRD) and x-ray photoelectron spectroscopy (XPS). Devices forI–V measurement and field-effect transistors (FETs) were assembled using ITOnanowires with top contact configurations. The effect of Sn doping on theelectrical conductivity was significant in that it enhanced the conductance by over107 times,up to ∼1 S cm−1 for ITO nanowires with an Sn content of 17.5 at.%. The nanowire FETswere operated in the depletion mode with an electron mobility of up to0.45 cm2 V−1 s−1 and anon/off ratio of 103.

Vertically aligned tin-doped indium oxide nanowire arrays: Epitaxial growth and electron field emission properties

Vertically aligned tin-doped indium oxide (ITO) single-crystalline nanowire arrays are epitaxially grown on ITO/yttrium stabilized zirconia substrates by vapor transport method. Vacuum electron field emission properties of the aligned ITO nanowires are investigated. The turn-on electrical field at a current density of 1μA∕cm2 is about 2.0V∕μm, and the lowest vacuum for an obvious emission is 1×10−1Pa. The good performance of field emission is attributed to the vertically aligned morphology, which has a stronger local electric field due to their orientation parallel to the electric-field direction.

Epitaxial Growth of Vertically Aligned and Branched Single‐Crystalline Tin‐Doped Indium Oxide Nanowire Arrays

Epitaxial Growth of Vertically Aligned and Branched Single‐Crystalline Tin‐Doped Indium Oxide Nanowire Arrays

Synthesis of tin-doped indium oxide nanowires by self-catalytic VLS growth

In this paper, bulk-quantity tin-doped indium oxide nanowires were successfully synthesized by direct thermal evaporation of a mixture of In and SnO powders in air at 920°C. Such nanowires have a uniform shape and single crystalline cubic bixbite structure, with the diameters varying from 100 to 200 nm and lengths in the range of tens to hundreds of micrometres. The growth process of these ternary oxide nanowires can be interpreted by a self-catalytic vapour–liquid–solid growth mechanism. This approach to synthesizing ternary oxides should be readily extensible to preparing other multinary oxide nanowires, such as Cd2SnO4, Zn–Sn–In–O, Ga–In–Sn–O, Cd–In–Sn–O and Zn–Sn–Cd–O nanowires or nanobelts.