G. N. Dar

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.

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.

A highly sensitive ammonia chemical sensor based on α-Fe2O3 nanoellipsoids

This paper reports the facile synthesis of ?-Fe2O3 nanoellipsoids by a low-temperature hydrothermal process and their effective utilization in the fabrication of a highly sensitive aqueous ammonia chemical sensor by the I?V technique. The as-synthesized ?-Fe2O3 nanoellipsoids are characterized in terms of their morphological, structural and optical properties. The detailed structural and optical properties confirm a rhombohedral ?-Fe2O3 structure and indirect (1.87?eV) and direct (2.15?eV) band gaps, respectively, for the synthesized nanoellipsoids. The fabricated aqueous ammonia sensor based on nanoellipsoids exhibits a very high and reproducible sensitivity of ~4.678??A?cm?2?mM?1 and a detection limit of ~0.04?nM with a correlation coefficient (R) of 0.995 in a short response time (10.0?s). The presented work demonstrates that simply synthesized iron oxide nanostructures can efficiently be used for the fabrication of reliable and reproducible chemical sensors.

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.

Low-temperature synthesis of α-Fe2O3 hexagonal nanoparticles for environmental remediation and smart sensor applications

This work demonstrates the successful synthesis and characterizations of α-Fe2O3 hexagonal nanoparticles and their effective utilization for the degradation of hazardous Rhodamine B (RhB) dye and smart chemical sensor applications. The as-synthesized materials were characterized by various analytical techniques which revealed that the prepared nanoparticles are well-crystalline, possessing hexagonal shape, grown in high-density and well matched with the rhombohedral α-Fe2O3 structures. The as-synthesized α-Fe2O3 nanoparticles were used as efficient photocatalyst for the photocatalytic degradation of RhB-dye under light illumination which showed substantial degradation (~79%) of RhB-dye in 140 min. The considerable photo-degradation of RhB-dye attributed to the unique morphology of the synthesized α-Fe2O3 nanoparticles which might import the effective electron/hole separation and generate the large number of oxy-radicals. Moreover, the synthesized α-Fe2O3 nanoparticles were utilized as efficient electron mediators for the fabrication of 4-nitrophenol chemical sensor in aqueous media. The fabricated chemical sensor exhibited a high-sensitivity of ~367.6 µA (mol L(-1))(-1) cm(-2) and an experimental detection limit of ~1.56×10(-3) mol L(-1) in a short response time of ~10.0 s with linearity in the range of 1.56×10(-3)-12.5×10(-3) mol L(-1) and correlation coefficient (R) of ~0.99963. These investigations demonstrated that the simply synthesized α-Fe2O3 nanoparticles can effectively be used as efficient photocatalyst for the photocatalytic degradation of organic dyes and effective electron mediators for the fabrication of highly sensitive chemical sensors in aqueous medium.

Growth and photocatalytic properties of Sb‐doped ZnO nanoneedles by hydrothermal process

This paper reports a facile hydrothermal synthesis of Sb‐doped ZnO nanoneedles by using aqueous mixtures of zinc chloride, antimony (Sb) chloride, hexamethylenetetramine (HMTA) and ammonium hydroxide at low temperature of 110 °C. The morphological characterizations of as‐synthesized nanoneedles were done by field emission scanning electron microscopy (FESEM) which reveals that the nanoneedles are grown in large‐quantity and arranged in such a special manner that they made flower‐like morphologies. The structural characterization of as‐synthesized nanoneedles was investigated by X‐ray diffraction (XRD) pattern which confirm the well‐crystalline and wurtzite hexagonal phase of as‐synthesized products. The compositional characterization of as‐synthesized nanoneedles was characterized by energy dispersive spectroscopy (EDS), which verify that the synthesized nanoneedles are composed of zinc, Sb and oxygen. For application point of view, the synthesized nanoneedles were used as photocatalyst for photocatalytic...

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.

Growth of branched In‐doped ZnO nanowires: Structural and Optical Properties

Well‐crystallized branched Indium (In)‐doped ZnO nanowires were grown on silicon substrate via simple thermal evaporation process by using metallic zinc and indium powders in the presence of oxygen. The as‐grown branched nanowires were examined in terms of their morphological, structural and optical properties using field emission scanning electron microscopy (FESEM) attached with energy dispersive spectroscopy (EDS), X‐ray diffraction and room‐temperature photoluminescence (PL) spectroscopy. The morphological and structural characterizations confirmed that the as‐grown products are branched nanowires, grown in high‐density and possessing well‐crystalline structures. The room‐temperature photoluminescence (PL) spectrum exhibited a very small UV emission and a broad band in the visible region indicating the presence of structural defects due to insertion of In‐atoms in the lattices of as‐grown nanowires. The presence of a strong green emission in the room‐temperature PL spectrum demonstrates that these str...