In this study, the effect of Sr- and Ni-doping on microstructural, morphological and sensing properties of ZnO nanorods has been investigated. Nanorods with different Sr and Ni loadings were prepared using a simple wet chemical method and characterized by means of scanning electron microscopy (SEM), X-ray diffraction (XRD) and photoluminescence (PL) analysis. XRD data confirmed that Sr- and Ni-doped samples maintainsthe wurtzite hexagonal structure of pure ZnO. However, unlikes Sr, Ni doping modifies the nanorod morphology, increases the surface area (SA) and decreases the ratio of IUV/Igreen photoluminescence peak to a greater extent. Sensing tests were performed on thick films resistive planar devices for monitoring CO and CO2, as indicators of indoor air quality.The effect of the operating temperature, nature and loading of dopant on the sensibility and selectivity of the fabricated sensors towards these two harmful gases were investigated. The gas sensing characteristics of Ni- and Sr-doped ZnO based sensors showed a remarkable enhancement (i. e. the response increased and shifted towards lower temperature for both gases) compared to ZnO-based one, demonstrating that these ZnO nanostructures are promising to fabricate sensor devices for monitoring indoor air quality.
We investigated the optical and optoelectronic properties of vertically aligned Al:ZnO nanorod arrays synthesized by the hydrothermal technique at a considerably low temperature on a sputtered Al-ZnO seed layer. The nanorod arrays maintained remarkable alignment along the c-axis over a large area. The seed layers and nanorod arrays showed various optical band gaps. Investigation of the optoelectronic properties of nanorod arrays on
ZnO is a promising material for the fabrication of light emitting devices. One approach to achieve this goal is to use ZnO nanorods because of their expected high crystalline and optical quality. Catalyst free growth of nanorods by metalorganic chemical vapour deposition (MOCVD) was carried out on (0001) sapphire substrates. Arrays of well-aligned, vertical nanorods were obtained with uniform lengths and diameters. A thin wetting layer in epitaxy with the sapphire substrate is formed first, followed by pyramids and nanorods. The nucleation of nanorods occurs either directly at the interface, o…
We carried out simulative investigations on a non-toxic, lead-free perovskite solar cell (PSC), where Cs2AgBiBr6, P3HT, ZnO nanorod, and C were utilized as the absorber layer, hole transport layer, electron transport layer, and back contact, respectively. At 600 nm optimum absorber thickness, the device achieved a maximum power conversion efficiency of 4.48%. The PSC operated optimally when the electron affinities were set at 3.3 eV and 4.6 eV for P3HT and ZnO nanorod, respectively. Moreover, the hole mobility and acceptor concentration of P3HT should be weighed during the choosing of appropri…
The fabrication of nanostructures with controlled assembly and architecture is significant for the development of novel nanomaterials-based devices. In this work we demonstrate that laser techniques coupled with low-temperature hydrothermal growth enable complex three-dimensional ZnO nanorods patterning on various types of substrates and geometries. The suggested methodology is based on a procedure involving the 3D scaffold fabrication using Multi-Photon Lithography of a photosensitive material, followed by Zn seeded Aqueous Chemical Growth of ZnO nanorods. 3D, uniformly aligned ZnO nanorods a…
In this letter, we have investigated the third-order optical nonlinearities of high-quality Ni doped ZnO nanorods crystallized in wurtzite lattice, prepared by the wet chemical method. In our experiments, we found that the two photon absorption coefficient beta increases by as much as 14 times i.e. 7.6 err 0.4 to 112 err 6 cm per GW, when the Ni doping is increased from 0 to 10 percent. The substantial enhancement in beta is discussed in terms of the bandgap scaling and Ni doping. Furthermore, we also show that the optical bandgap measured by UVVis and photo luminescence spectroscopic, continu…
The controlled modification of the electronic properties of ZnO nanorods via transition metal doping is reported. A series of ZnO nanorods were synthesized by chemical bath growth with varying Co content from 0 to 20 atomic % in the growth solution. Optoelectronic behavior was probed using cathodoluminescence, time-resolved luminescence, transient absorbance spectroscopy, and the incident photon-to-current conversion efficiency (IPCE). Analysis indicates the crucial role of surface defects in determining the electronic behavior. Significantly, Co-doping extends the light absorption of the nano…
The piezoelectric nanomaterial ZnO exhibits an excellent piezoelectric response that can transduce mechanical energy into electrical signals by applying pressure. The piezoelectric behavior of ZnO nanostructures (especially nanorods or microrods) is getting considerable attention in the fabrications of piezo tactile sensors, energy harvesting devices, and other self-powering implantable devices. Especially vertically aligned ZnO nanorods are of high interest due to their higher value of piezoelectric coefficient along the z-direction. In this report, various geometries and alignments of ZnO na…
In this work, hybridization of nonmetal nitrogen-doped carbon dots (NCQDs) with ZnO nanorods (NRs) is utilized towards better photocatalytic degradation of rhodamine B under ultraviolet (UV) irradiation. The structural characterization is confirmed by XRD, XPS, FTIR and HRTEM measurements, while, optical properties have been investigated using UV-visible absorbance spectroscopy and photoluminescence study. The dye degradation using ZnO NR is recorded as ~69%, while the performance of ZnO/NCQD climbs up to ~90%, after nine minutes of UV irradiation. Furthermore, the reusability test suggests be…
In this study, we report the enhancement in field emission (FE) properties of ZnO nanostructure by Ni doping at the base pressure of ~1 x 10-8 mbar, which were grown by the simple wet chemical process. ZnO nanostructure shows single crystalline wurtzite structure up to Ni 10% doping. FESEM represents change in the nanostructure morphology from thick nanoneedles to nanoflakes via thin nanorods with increase in Ni doped ZnO. The turn-on field required to draw a field emission (FE) current density at 1μA/cm2 is found to be 2.5, 2.3, 1.8 and 1.7 V/μm for ZnO(Ni0%), ZnO(Ni5%), ZnO(Ni7.5%) and ZnO(N…
We report the electronic structure studies of well characterized polycrystalline Zn_{1-x}Fe_xO (x = 0.0, 0.01, 0.03, and 0.05) nanorods synthesized by a co-precipitation method through x-ray absorption fine structure (XAFS). X-ray diffraction (XRD) reveals that Fe doped ZnO crystallizes in a single phase wurtzite structure without any secondary phase. From the XRD pattern, it is observed that peak positions shift towards lower 2θvalue with Fe doping. The change in the peak positions with increase in Fe contents clearly indicates that Fe ions are replacing Zn ions in the ZnO matrix. Linear comb…
Sr doped ZnO nanorods thin films are prepared using wet chemical technique on transparent flexible substrate. Effect of Sr doping on structural and optical properties of ZnO is systematically investigated. The sensing property of the ZnO is enhanced by Sr doping and imitates as a promising material for future toxic and flammable gas sensor applications as well as for optoelectronic devices.
Orientation dependent electronic properties of wurtzite zinc oxide nanorods are characterized by aloof beam electron energy-loss spectroscopy (EELS) carried out in a scanning transmission electron microscope (STEM). The two key crystal orientation differentiating transitions specific to the in-plane (13.0 eV) and out-of-plane (11.2 eV) directions with respect to the wurtzite structure are examined by first principles density-functional theory calculations. We note some degree of orientation dependence at the onset of direct band gap transition near 3.4 eV. We demonstrate that good polarization…
This work reports the successful solid state synthesis of ZnO/NiFe2O4 nanocomposite by calcinations of both green synthesized ZnO nanorods and NiFe2O4 prismatic nanorods at high temperature (850 °C) for ten hours. These nanomaterials were characterized for structural, functional groups and morphological studies using XRD, FTIR and SEM respectively. The photocatalytic activity of the catalysts was assessed through photodegradation of methylene blue (MB) dye. The photocatalytic studies reveal that the ZnO/NiFe2O4 nanocomposite exhibits high degradation efficiency under UV light. The study shows …
Vertically aligned, beaded zinc germinate (Zn2GeO4)/ zinc oxide (ZnO) hybrid nanowire arrays were successfully synthesized by a vapor-solid process via a catalyst-free approach. The as-synthesized products were characterized using X-ray diffraction, scanning electron microscopy and transmission electron microscopy equipped with an energy-dispersive X-ray spectrometer. TEM studies revealed the beaded microstructures of the Zn2GeO4/ZnO nanowire. Furthermore, Zn2GeO4 nanotubes were synthesized after wet etching treatments on Zn2GeO4/ZnO hybrid nanowires.
Crystals grow by gathering and bonding of atoms to form an ordered structure. Typically, the growth is equally probable in all crystalline directions, but sometimes, it is not, as is the case of nanowire growth. Nanowire growth is explained, in most cases, by the presence of liquid metal droplets that mediate between an incoming flux of atoms and a substrate or an existing crystal nucleus, while defining the lateral dimension. Here, we report and explain a previously unknown mode of non-isotropic crystal growth observed in two wurtzite semiconductors, InN and ZnO. Being of polar structure, wur…
The composites of strontium-doped lanthanum manganite (LSMO) with zinc oxide (ZnO) are candidate materials for energy harvesting by virtue of their magnetic and piezoelectric characteristics. They could be used to harvest energy from stray sources, such as the vibrations and electromagnetic noise from transformers and compressors within electrical grid power stations to power small diagnostic sensors, among other applications. The LSMO/ZnO nanocomposites were made by: (i) milling the two bulk powders and, (ii) a wet chemical process which resulted in core-shell structures. The electrical, piez…
Crystal structure, cobalt and iron speciation and oxygen non-stoichiometry of La0.6Sr0.4Co1-yFeyO3-d nanorods for IT-SOFC cathodes
Pontificia Universidad Javeriana（波哥大耶稣会天主教大学）；Centro Atómico Constituyentes, Comisión Nacional de Energía Atómica（康塞普西翁原子中心，国家原子能委员会）；Instituto de Nanociencia y Nanotecnología (INN), CNEA-CONICET（纳米科学与技术研究所，国家原子能委员会-国家科学研究和技术研究委员会）；CONICET / Laboratorio de Cristalografía Aplicada, Escuela de Ciencia y Tecnología, Universidad Nacional de Gral. San Martín（国家科学研究和技术研究委员会/应用晶体学实验室，科学与科技学院，圣马丁国立大学）；CNPEM, Laboratório Nacional de Luz Síncrotron（巴西纳米技术国家研究中心，同步光国家实验室）；Instituto de Física, Universidade de São Paulo（物理研究所，圣保罗大学）
Nanocomposite metal oxide thin films exhibit assuring qualities in the field of gas sensors because of the collective opportunities provided by the heterointerface formation. In this work, we present the synthesis of nitrogen doped mesoporous In$_2$O$_3$-ZnO nano-composite thin films by simple wet chemical method using urea as the nitrogen precursor. SEM investigation suggests formation of mesoporous nano-composite thin films, where the uniformity of surface pore distribution depends on the relative proportion of In$_2$O$_3$ and ZnO in the composites. HRTEM investigation suggest formation of s…
