Synthesis and Characterization of Mimosa Pudica Leaves Shaped α-Iron Oxide Nanostructures for Ethanol Chemical Sensor Applications.

Herein, the synthesis of mimosa pudica leaves shaped a-iron oxide (α-Fe2O3) nanostructures is reported through simple and facile hydrothermal process. The prepared α-Fe2O3 nanostructures were characterized in terms of their morphological, structural, compositional and optical properties through a variety of characterization techniques such as FESEM, EDS, XRD, FTIR and Raman spectroscopy. The detailed characterizations revealed the well-crystallinity and dense growth of mimosa pudica leaf shaped α-Fe2O3 nanostructures. Further, the prepared nanomaterials were used as efficient electron mediator to fabricate sensitive ethanol chemical sensor. The fabricated sensor exhibited a high sensitivity of -30.37 µAmM(-1) cm(-2) and low detection limit of -0.62 µM. The observed linear dynamic range (LDR) was in the range from 10 µM-0.625 µM.

Fabrication and Characterization of Field Effect Transistor Based on High-Aspect Ratio Sulfur-Doped ZnO Nanowires.

Well-crystalline sulfur (S) doped ZnO nanowires have been grown via a simple thermal evaporation process on Si substrate using high purity zinc and sulfur powders in presence of oxygen. The as-grown S:ZnO nanowires were characterized in terms of their morphological structural, compositional and optical properties using several techniques such as FESEM, TEM, XRD, EDS and PL. The morphological characterizations revealed that the as-grown nanowires had diameters in the range of 60-100 nm with lengths 5-15 µm. The details structural properties confirmed the well-crystallinity and wurtzite hexagonal phase for the prepared nanowires. Room temperature photoluminescence (PL) spectrum showed a strong green band with a suppressed UV emission. The electrical properties of single S:ZnO nanowire was examined by fabricating single nanowire based field effect transistors (FETs). The detailed electrical transport results showed that S:ZnO nanowires possess n-type semiconducting behavior and exhibited an electron mobility of -67.7 cm2 V(-1) s(-1) and a carrier concentration of 2 x 10(17) cm(-3), respectively.

Low-temperature growth of aligned ZnO nanorods: effect of annealing gases on the structural and optical properties.

Aligned ZnO nanorods were grown on ZnO/Si substrate via simple aqueous solution process at low-temperature of - 65 degrees C by using zinc nitrate and hexamethylenetetramine (HMTA). The detailed morphological and structural properties measured by FESEM, XRD, EDS and TEM confirmed that the as-grown nanorods are vertically aligned, well-crystalline possessing wurtzite hexagonal phase and grown along the [0001] direction. The room-temperature photoluminescence spectrum of the grown nanorods exhibited a strong and broad green emission and small ultraviolet emission. The as-prepared ZnO nanorods were post-annealed in nitrogen (N2) and oxygen (O2) environments and further characterized in terms of their morphological, structural and optical properties. After annealing the nanorods exhibit well-crystallinity and wurtzite hexagonal phase. Moreover, by annealing the PL spectra show the enhancement in the UV emission and suppression in the green emission. The presented results demonstrate that simply by post-annealing process, the optical properties of ZnO nanostructures can be controlled.

Visible-light-driven photocatalytic and chemical sensing properties of SnS2 nanoflakes.

This work demonstrated the successful and facile large-scale synthesis and characterizations of SnS2 nanoflakes. The detailed morphological studies revealed that the synthesized products were nanoflakes and were grown in large quantity. The XRD pattern and detailed compositional studies confirmed that the synthesized SnS2 nanoflakes were well-crystalline and possessing hexagonal SnS2 phase. The synthesized SnS2 nanoflakes were used as efficient photocatalysts for photocatalytic degradation and effective electron mediators for the fabrication of chemical sensor. The photocatalytic properties of SnS2 nanoflakes towards the photocatalytic degradation of Rhodamine B dye under visible light irradiation showed reasonably good degradation of ~61%. Moreover, the as-synthesized SnS2 nanoflakes were used as efficient electron mediators for the fabrication of nitroaniline chemical sensor by simple I-V technique. Very high-sensitivity of ~ 505.82±0.02 mAcm(-2).(mole/L)(-1) and experimental detection limit of ~15×10(-6) (mole/L) in a short response time of ~10.0 s with LDR in the range of 15.6×10(-6)-0.5×10(-3) mole L(-1) were observed for the fabricated nitroaniline chemical sensor. The observed results indicated that the SnS2 nanoflakes can efficiently be used as visible-light-driven photocatalysts and the fabrication of ultra-high sensitive chemical sensors.

Growth and properties of Ag-doped ZnO nanoflowers for highly sensitive phenyl hydrazine chemical sensor application.

We report here the fabrication of a robust, highly sensitive, reliable and reproducible phenyl hydrazine chemical sensor using Ag-doped ZnO nanoflowers as efficient electron mediators. The Ag-doped ZnO nanoflowers were synthesized by facile hydrothermal process at low-temperature and characterized in detail in terms of their morphological, structural, compositional and optical properties. The detailed morphological and structural characterizations revealed that the synthesized nanostructures were flower-shaped, grown in very high-density, and possessed well-crystalline structure. The chemical composition confirmed the presence of Ag into the lattices of Ag-doped ZnO nanoflowers. High sensitivity of ≈ 557.108 ± 0.012 mAcm(-2)(mol L(-1))(-1) and detection limit of ≈ 5 × 10(-9) mol L(-1) with correlation coefficient (R) of 0.97712 and short response time (10.0 s) were observed for the fabricated chemical sensor towards the detection of phenyl hydrazine by using a simple current-voltage (I-V) technique. Due to high sensitivity and low-detection limit, it can be concluded that Ag-doped ZnO nanoflowers could be an effective candidate for the fabrication of phenyl hydrazine chemical sensors.

Ultra-high sensitive ammonia chemical sensor based on ZnO nanopencils.

This paper reports a very simple, reliable and facile methodology to fabricate ultra-high sensitive liquid ammonia chemical sensor using well-crystalline hexagonal-shaped ZnO nanopencils as an efficient electron mediator. A low-temperature facile hydrothermal technique was used to synthesize ZnO nanopencils. The synthesized nanopencils were characterized in detail in terms of their morphological, structural and optical properties which confirmed that the synthesized nanomaterial is well-crystalline, possessing wurtzite hexagonal phase and possess very good optical properties. A very high sensitivity of ≈ 26.58µAcm(-2)mM(-1) and detection limit of ≈ 5nM with a correlation coefficient (R) of 0.9965 and a response time of less than 10s were observed for the fabricated liquid ammonia by I-V technique. To the best of our knowledge, by comparing the literature, it is confirmed that the fabricated sensor based on ZnO nanopencils exhibits highest sensitivity and lowest detection limit for liquid ammonia. This research opens a way that simply synthesized nanomaterials could be used as efficient electron mediators for the fabrication of efficient liquid ammonia chemical sensors.

Synthesis and characterizations of Cd-doped ZnO multipods for environmental remediation application.

Well-crystalline Cd-doped ZnO multipods were synthesized by simple and facile hydrothermal process by using zinc chloride, cadmium chloride, hexamethylenetetramine and ammonium hydroxide at low-temperature. The synthesized materials were characterized in terms of their morphological, structural, compositional and optical properties. The morphological investigations done by field emission scanning electron microscopy (FESEM) reveal that the synthesized products are multipods shaped and grown in high density. The structural and compositional properties, observed by X-ray diffraction (XRD), energy dispersive spectroscopy (EDS) attached with FESEM and Fourier transform infrared (FTIR) spectroscopy exhibit that the synthesized multipods are well-crystalline and possessing wurtzite hexagonal phase pure Cd-doped ZnO. The as-synthesized Cd-doped ZnO multipods exhibited good optical properties as was confirmed by UV-vis. spectroscopy. Finally, the as-synthesized Cd-doped ZnO multipods were used environmental remediation application. For this, the synthesized multipods were used as an effective photocatalyst for the photocatalytic degradation of acridine orange (AO) which exhibit -92.4% degradation within 90 min. This work demonstrates that doped ZnO materials could be used as efficient photocatalyst for the photocatalytic degradation of various organic dyes and chemicals.

Well-crystalline ZnO nanowire based field effect transistors (FETs).

Well-crystalline ZnO nanowires were grown on Si(100) via non-catalytic thermal evaporation process using metallic zinc powder in presence of oxygen. The detailed morphological characterizations by field emission scanning electron microscopy (FESEM) and transmission electron microscopy (TEM) confirmed that the synthesized products are nanowires with the typical diameter and lengths of approximately 55 +/- 5 nm and several micrometers, respectively and are grown in high density over the silicon substrate. The detailed structural characterizations by high-resolution TEM and X-ray diffraction confirmed that the synthesized nanowires are well-crystalline and possessing wurtzite hexagonal phase. The presence of Raman-active optical-phonon E2(high) mode at 437 cm(-1) in the Raman-scattering spectrum confirms good crystal quality for the as-grown ZnO nanowires. The electrical transport properties of the as-grown nanowires were explored by fabricating single nanowire based field effect transistors (FETs). The fabricated single ZnO nanowire based FET exhibits carrier concentration and electron mobility of approximately 7.49 x 10(17) cm(-3) and approximately 8.42 cm2V(-1)s(-1), respectively.

High-yield synthesis of well-crystalline alpha-Fe2O3 nanoparticles: structural, optical and photocatalytic properties.

In this paper, the high-yield facile synthesis, detailed characterization and photocatalytic application of alpha-Fe2O3 nanoparticles are reported. The synthesis was done via simple hydrothermal process by using aqueous mixtures of iron chloride, hexamethylenediamine and NH3 x H2O at 110 degrees C. The morphologies of the synthesized products were examined by using field emission scanning electron microscopy (FESEM) and transmission electron microscopy (TEM) which confirmed that the synthesized structures are almost spherical shaped nanoparticles with the average diameters of -35 +/- 5 nm, and are grown in high yield. The detailed structural characterizations and composition of the as-synthesized nanoparticles were investigated by using X-ray diffraction (XRD), high-resolution TEM (HRTEM), energy dispersive spectroscopy (EDS) attached with FESEM and Fourier transform infrared spectroscopy (FTIR) which substantiated that the as-synthesized nanoparticles are well crystalline and pure alpha-Fe2O3. The UV-Vis absorption spectrum of the synthesized nanoparticles demonstrated the existence of two optical band gaps which correspond to direct and indirect transitions, respectively. The as-synthesized alpha-Fe2O3 nanoparticles exhibit good photocatalytic properties on photocatalytic degradation of methylene blue.