Synthesis Of SnO2 Nanowires Research Articles

Synthesis of SnO2 nanowires using thermal chemical vapor deposition with SnO powder and their application as self-powered ultraviolet photodetectors

We report on the performance of self-powered ultraviolet (UV) photodetectors composed of SnO2 nanowire (NW) networks. SnO2 NWs with a length of several hundred micrometers can be synthesized by thermal chemical vapor deposition (CVD) using SnO powder as the raw material, which has the advantages of a low process temperature and no requirement for a reducing agent. Based on the characterization results obtained through synchrotron X-ray diffraction (XRD), scanning electron microscopy, and transmission electron microscopy (TEM), we determined the growth behavior of SnO2 NWs via a vapor-liquid-solid mechanism with Au nanoparticles. The NW growth switched from an initial in-plane growth to subsequent vertical growth, forming NW cotton. This was started at a process temperature of 600 ℃ and optimized at 800 ℃. Moreover, the XRD and TEM results indicate that the NWs mainly grew in the form of SnO2, although the formation of SnO NWs was also possible. Metal−SnO2 NW−metal type photodetectors were fabricated, and their photoresponsivity to UV light in the range from 200 to 400 nm was investigated. The device exhibited a photo-to-dark current ratio of ∼2.17 × 106 at an applied bias of 10 V and 254 nm UV exposure. A maximum responsivity of about 1100 A/W was estimated at a wavelength of 270 nm, and the cutoff edge wavelength appeared around 350 nm. In particular, the self-powered photoresponse at nominal zero bias was ∼1.23 nA. The results of this study support the idea that SnO2 NWs are promising candidates for self-powered deep-UV photodetectors and that thermal CVD using SnO powder is suitable for synthesizing SnO2 NWs at temperatures as low as 700 °C.

Antimony doped SnO2 nanowire@C core–shell structure as a high-performance anode material for lithium-ion battery

SnO2 is considered as one of the high specific capacity anode materials for Lithium-ion batteries. However, the low electrical conductivity of SnO2 limits its applications. This manuscript reports a simple and efficient approach for the synthesis of Sb-doped SnO2 nanowires (NWs) core and carbon shell structure which effectively enhances the electrical conductivity and electrochemical performance of SnO2 nanostructures. Sb doping was performed during the vapor-liquid-solid synthesis of SnO2 NWs in a horizontal furnace. Subsequently, carbon nanolayer was coated on the NWs using the DC Plasma Enhanced Chemical Vapor Deposition approach. The carbon-coated shell improves the Solid-Electrolyte Interphase stability and alleviates the volume expansion of the anode electrode during charging and discharging. The Sb-doped SnO2 core carbon shell anode showed the superior specific capacity of 585 mAhg−1 after 100 cycles at the current density of 100 mA g−1, compared to the pure SnO2 NWs electrode. The cycle stability evaluation revealed that the discharge capacity of pure SnO2 NWs and Sb doped SnO2 NWs electrodes were dropped to 52 and 152 mAh g−1 after100th cycles. The process of Sb doping and carbon nano shielding of SnO2 nanostructures is proposed for noticeable improvement of the anode performance for SnO2 based materials.

Synthesis of SnO2 Nanowires on Quartz and Silicon Substrates for Gas Sensors

Tin oxide nanowires (SnO2 NWs) were grown on quartz and silicon substrates via a modified chemical vapor deposition (CVD). Film of gold nanoparticle deposited on both types of substrates using the direct current DC-sputtering technique. The structure and morphology of the produced material were characterized by using atomic force microscopy, X-ray diffraction (XRD), scanning electron microscope (SEM) and ultraviolet–visible (UV–Vis) techniques. The XRD and SEM analysis confirmed the formation of tetragonal SnO2 NWs with a wire length of 10–20 μm and a diameter of 40–100 nm. The UV–Vis spectrum shows a strong absorption peak in the UV and others in the visible regions. The bandgap was calculated for SnO2 NWs grown on a quartz substrate within the value of 3.2 eV. It is slightly lower than the bandgap value of bulk. The successfully synthesized SnO2 NWs via CVD with a large aspect ratio in the range of 250–200 was proved to be quite promising nanomaterials to use for sensor fabrication towards ethanol gas at room temperature. The high sensitivity of 2.7 at an ethanol gas concentration of 500 parts per million (ppm) was achieved. The proposed sensing mechanism of SnO2 NWs towards ethanol gas was also discussed.

Synthesis of SnO2 nanowires as a reusable and flexible electrode for electrochemical detection of riboflavin

The fabrication and testing of a riboflavin (RF) sensor based on the use of tin oxide (SnO2) nanowires was successfully attained. Template directed electrodeposition was used to produce one-dimensional nanostructures of SnO2. SnO2 nanowires were achieved by the electrodeposition of tin(ii) chloride into the nanochannels of the porous polycarbonate membrane by applying potential of −0.75 V. Various techniques such as XRD, FESEM, EDS and FTIR were used to characterize the synthesized nanowires. All electrochemical studies were carried out in phosphate buffer pH 7.0 and 0.1 Vs−1 scan rate. The fabricated sensor showed excellent anti-interference ability against electroactive species and metal ions. It also proved its long-term stability and good reproducibility with RSD values 1.90% and 1.30% respectively. The voltammetric signal increases linearly in the 0–13 μM concentrations range with a lower detection limit of 0.6 µM. Rs and Rct values decreased significantly with increasing concentration. The synthesized electrode is proved to be useful for the estimation of the RF content in pharmaceutical samples with 98% recovery.

SnO2 nanowire gas sensors for detection of ppb level NOx gas

Until now, SnO2 nanowires have been directly grown on alumina substrates with Au or Au-coated Pt electrodes by a thermal evaporation method using Sn or SnO2 powders under vacuum. However, in this study, SnO2 nanowires were successfully synthesized on the Pt phase of an alumina substrate by a thermal evaporation method using dibutyltin oxide [DBTO, (C4H9)2SnO] even at atmospheric pressure, resulting in nanowire networks between the Pt phases. Ar with 1% O2 was used as carrier gas with a flow rate of 100 mL/min at 900 °C (heating rate of 25 °C/min). The SnO2 nanowires consisted of straight and branched nanowires, and exhibited a SnO2 phase with a tetragonal structure. Both the DBTO and evaporation temperature play an important role on the synthesis of SnO2 nanowires at atmospheric pressure. The SnO2 nanowire sensor fabricated by an evaporation method showed a sensor response of ~ 500 for 0.05 ppm of NO2, being ~ 10 times greater than that of a SnO2 nanoparticle sensor. Furthermore, the SnO2 nanowire sensor showed excellent repeatability and selectivity for NO2 in the presence of SO2, Cl2, and H2S.

UV-Enhanced NO2 Gas Sensing Properties of SnO2-Core/ZnO-Shell Nanowires at Room Temperature

SnO2-core/ZnO-shell nanowires were synthesized using a two-step process: the synthesis of SnO2 nanowires by the thermal evaporation of Sn powders followed by the atomic layer deposition of ZnO. The room temperature NO2 gas sensing properties of the nanowires under ultraviolet (UV) illumination were examined. The cores and shells of the nanowires were primitive tetragonal-structured single crystal SnO2 and wurtzite-structured single crystal ZnO, respectively. The responses of multiple networked SnO2 nanowire sensors were increased 2-3-fold at NO2 concentrations ranging from 1 to 5 ppm by encapsulating the nanowires with ZnO. The SnO2-core/ZnO-shell nanowire sensors showed a remarkably enhanced response under UV illumination. The sensing mechanism of the core/shell nanowires under UV illumination is also discussed.

Synthesis of SnO2 nanowires their structural and H2 gas sensing properties

SnO 2 nanowires were prepared on bare oxidized silicon, Au and SnO 2 -coated substrates by thermal evaporation of tin grains in argon atmosphere at 900 °C. X-ray diffraction (XRD) and field-emission scanning electron microscopy (FE-SEM) were used to characterize the SnO 2 nanowires. FE-SEM images indicated that the size of SnO 2 nanowires depend on the type of substrate. Gas sensor was fabricated by dispersing SnO 2 nanowires on an interdigitated Pt-electrode. H 2 gas sensing properties of these sensors made of nanowires prepared on three different substrates were measured at various operating temperatures and concentrations respectively. SnO 2 nanowires deposited on Au-coated substrates showed the highest sensitivity of 11.5 at 100 °C upon exposure to H 2 gas of 1000 ppm.

Switchable Wettability in SnO2 Nanowires and SnO2@SnO2 Heterostructures

We present here the synthesis of SnO2 nanowires SnO2@SnO2 and SnO2@SnO2@SiOx heterostructures via the chemical vapor deposition (CVD) method. Surface wettability could be modulated from superhydrophilic to superhydrophobic by changing both chemical composition and the geometrical architecture of nanoheterostructures. The random SnO2 nanowires with a contact angle of 3° presented a superhydrophilic property. The contact angle of SnO2@SnO2 heterostructures synthesized by a two-step CVD process increased to 133°. The corresponding contact angle of SnO2@SnO2@SiOx heterostructures was 155.8°. Switchable surface wettability of the SnO2@SnO2@SiOx heterostructure was observed by alternation of UV irradiation, dark storage, and O2 annealing, indicating that geometric microstructure was the major determinant in the switchable wettability from superhydrophilic to superhydrophobic. The switchable surface wettability of SnO2 nanostructures may develop the significant potential for industrial coating and self-cleaning ...

Size- and Surface-dependent Photoresistance in SnO2 Nanowires

AbstractNanostructured one-dimensional materials, such as nanowires, tubes and rods, are gaining increasing attention due to interesting properties and confinement effects, however controlled synthesis of these structures is still limited to a few methods. We present here the synthesis of SnO2 nanowires (Ø, 50 – 1000 nm) at moderate temperatures (550 – 900 °C) using a molecular source [Sn(OBut)4] with pre-existent Sn-O bonds. The growth occurs via a catalyst driven vapor-solid-solid mechanism. Size-selective synthesis of NWs in high areal density was achieved by choosing Au particles of appropriate size. HR-TEM analysis reveals the single crystalline behaviour of wires with a preferred growth direction [100]. Use of SnO2 nanowires as potential optical switches for UV applications was demonstrated by the photo-response measurements. Determination of band gap values confirmed the blue-shift of the main photo-response peak with shrinking radial dimensions of the wires. Furthermore, deposition of vanadium oxide onto SnO2 led to a red-shift of the main conduction value of the nanowires.

Preparation and Characterization of Tin Oxide Nanowires for Gas Sensing

AbstractEfficient and reliable laser-ablation approaches for large-scale synthesis of SnO2 nanowires are reported. Transmission electron microscopy (TEM) and x-ray diffraction (XRD) were used to confirm the crystal structure of the nanowires. The results show that these nanowires had uniform diameters around 20 nm and lengths in the order of 10 νm. In addition, field effect transistors have been constructed based on individual SnO2 nanowires. Excellent n-type transistor characteristics have been observed for SnO2 nanowire transistors. Detailed analysis revealed threshold voltages ∼ -50V with on/off ratios as high as 103 at room temperature. These nanowire transistors were further demonstrated to work as sensitive UV detectors and gas sensors.