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Synthesizing, characterizing, and toxicity evaluating of Phycocyanin-ZnO nanorod composites: A back to nature approaches
摘要： C-Phycocyanin pigment was purified from a native cyanobacterial strain using a novel consecutive multi-step procedure and utilized for the first time for the green synthesis of phycocyanin-zinc oxide nanorods (PHY-ZnO NRs) by a simple, low-cost and eco-friendly approach. The PHY-ZnO NRs were characterized using UV-Vis spectroscopy, X-ray diffraction (XRD), zeta potential measurement, FTIR, SEM, TEM, differential scanning calorimetry (DSC), thermogravimetric (TGA), and EDX spectroscopy analysis. The UV-Vis spectra showed an absorption band at 364 nm which is characteristic of ZnO nanoparticles (ZnONPs). The rod-shaped PHY-ZnO NRs observed in the TEM and SEM images had an average diameter size of 33 nm, which was in good agreement with the size calculated by XRD. The elemental analysis of PHY-ZnO NRs composition showed that three emission peaks of zinc metal and one emission peak of oxygen comprised 33.88% and 42.50%, respectively. The thermogram of PHY-ZnO NRs sample exhibited the weight loss of biosynthesized nanoparticles registered to be 3 %, emphasizing the purity and heat stability of zinc oxide nanorods coated with phycocyanin pigment-protein. MTT assay indicated that PHY-ZnO NRs had a less cytotoxicity on fibroblast L929 compared to the ZnONRs-treated cells. A remarkable increase in ROS level was measured in cells treated with ZnO at final concentrations of 100, 200 and 500 μg/ml (78±7, 99±8 and 116±11, respectively). When it comes to PHY-ZnO NRs, a protective effect for phycocyanin was detected which declined the level of ROS content as confirmed by fluorescent microscopy. The distinctive features of phycocyanin for surface functionalization of ZnO nanoparticles deserve to be deemed as a nano-drug candidate for further researches.
关键词： Cyanobacteria,Green synthesis,MTT assay,Phycocyanin,Zinc oxide nanoparticles
更新于2025-09-10 09:29:36
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Design and analysis of electrostatic-charge plasma based dopingless IGZO vertical nanowire FET for ammonia gas sensing
摘要： In this paper, Dopingless Gate All Around (GAA) Vertical Nanowire Field Effect Transistor (VNWFET) is designed with artificial material Indium Gallium Zinc Oxide (IGZO) as a channel material. IGZO channel has high electron mobility compared to more traditional amorphous semiconductors. In VNWFETs, since the channel length (Lch) is characterized vertically, it can be relaxed without area penalty on-chip, which in turn also allows some relaxation in the nanowire diameter while keeping optimum short-channel-effects control. Electrostatic-Charge Plasma technique is used to form a source-drain region on an intrinsic body of IGZO material. At the source side, the N+ region is formed by selecting the appropriate work function of the metal electrode, and at the drain side, the N+ region is formed by giving biasing to the metal electrode. N+ channel dopingless VNWFET with the catalytic metal gate is proposed for ammonia gas sensing. Cobalt, Molybdenum, and Ruthenium are used as a gate electrode in ammonia gas detection due to their high reactivity towards ammonia. Also, we have compared their ON and OFF sensitivity of the proposed device toward the gas adsorption. Due to the presence of gas on the gate, the metal work function of gate metal changes which varies the OFF-current (IOFF), ON-current (ION) and Threshold voltage (Vth) as these are considered as sensitivity parameters for sensing the ammonia gas molecules. The dimensional parameters (radius, and length) and dielectric materials are varied to check the change in device sensitivities. Results show that as the work function varies increases 50, 100, 150, 200meV and 250meV for catalytic metal at the gate, the sensitivity is increased.
关键词： Vertical nanowire FET (VNWFET),Indium Gallium Zinc Oxide (IGZO),Electrostatic-Charge Plasma (E-CP),Ammonia Gas sensor
更新于2025-09-10 09:29:36
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Botanically Templated Monolithic Macrostructured Zinc Oxide Materials for Photocatalysis
摘要： With an increased focus on light energy to facilitate catalytic processes, photocatalysts have been intensively studied for a wide range of energy and environmental applications. In this report, we describe the use of chemically dehydrated leaves as sacrificial foam-like templates for the growth of monolithic macrostructured semiconducting zinc oxide and nickel or cobalt doped zinc oxide materials. The composition and structure of these templated zinc oxides were characterized using X-ray powder diffraction, scanning electron microscopy, energy dispersive spectroscopy, and X-ray photoelectron spectroscopy. Optical properties were examined using solid-state UV–vis diffuse reflectance spectroscopy. The metal-doped ZnO materials have enhanced visible absorption and lower band gaps as compared to ZnO. The botanically templated ZnO materials retain the macroscopic cellular form of the leaf template with fused nanoparticle walls. Their UV photocatalytic oxidative abilities were investigated using methylene blue dye degradation in air. The leaf templated zinc oxides degrade ~85% of methylene blue dye with 30 min of UV illumination. Nickel and cobalt doped zinc oxides showed varying degrees of decreased UV and visible light photocatalytic activity, possibly due to metal-mediated charge recombination. The mild chemical dehydration process here allows complex soft botanical structures to be easily utilized for templating materials.
关键词： macrostructured,botanical templating,metal doping,zinc oxide,photocatalysis
更新于2025-09-10 09:29:36
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Enhancing optical absorption in visible light of ZnO co-doped with europium and promethium by first principles study through modified Becke and Johnson potential scheme
摘要： By using first-principle calculations we studied the electronic, optical and magnetic properties of ZnO co-doped with Eu and Pm. In this calculation, we used Wien2k code based on Full potential linearized augmented plane waves (FP-LAPW) method with the modified Becke-Johnson (mBJ) approximation. This correction gives good band gap compared to experimental band gap. The introduction of Eu and Pm codoping leads to an increase in the band gap. Electrons can transit easily from the valence band to the conduction band, which results in an enhancement of visible light absorption in a wider absorption range. Absorption spectra reach a high value in visible and infrared light regions. With the significance of the obtained results, the studied compounds may potentially find spintronic and optoelectronic applications.
关键词： transmittance,Zinc Oxide,density functional theory,band gap,spintronics,Rare Earth,magnetic properties,absorption,modified Becke-Johnson,photovoltaic
更新于2025-09-10 09:29:36
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Potentials of Costus woodsonii leaf extract in producing narrow band gap ZnO nanoparticles
摘要： Narrow band gap zinc oxide (ZnO) nanoparticles (NPs) were synthesized using unboiled and boiled leaf extracts of Costus woodsonii. The as-synthesized NPs were characterized using a range of techniques. The as-synthesized ZnO NPs were crystalline with a hexagonal wurtzite structure similar to the commercial ZnO (ZnO-C). The maximum absorbance was observed at ~390 nm for ZnO-C and the as-synthesized ZnO NPs (ZnO-UL and ZnO-BL) showed a red shift, i.e. ~448 nm to ~462 nm, hence, a lower band gap of ~2.68–2.77 eV. The band gap energy of the as-synthesized ZnO NPs was lower than that of commercial ZnO. The surface of ZnO was coated/modified with the components of the leaf extract. The as-synthesized ZnO NPs showed similar particle sizes and were spherical in shape. These studies confirmed the green synthesis of ZnO NPs using Costus woodsonii and the significantly reduced band gap (Eg = ~2.68 eV to ~2.77 eV) of the as-synthesized ZnO NPs compared to the ZnO-C (Eg = 3.18 eV).
关键词： Costus woodsonii,Zinc Oxide,Metal oxides,ZnO,Green synthesis,Leaf extracts
更新于2025-09-10 09:29:36
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Photocurrent Characteristics of Zinc-Oxide Films Prepared by Using Sputtering and Spin-Coating Methods
摘要： The photocurrent characteristics of zinc-oxide (ZnO) thin-film transistors (TFTs) prepared using radio-frequency sputtering and spin-coating methods were investigated. Various characterization methods were used to compare the physical and the chemical properties of the sputtered and the spin-coated ZnO films. X-ray photoelectron spectroscopy was used to investigate the chemical composition and state of the ZnO films. The transmittance and the optical band gap were measured by using UV-vis spectrometry. The crystal structures of the prepared ZnO films were examined by using an X-ray diffractometer, and the surfaces of the films were investigated by using scanning electron microscopy. ZnO TFTs were prepared using both sputter and solution processes, both of which showed photocurrent characteristics when illuminated by light. The sputtered ZnO TFTs had a photoresponsivity of 3.08 mA/W under illumination with 405-nm light while the solution-processed ZnO TFTs had a photoresponsivity of 5.56 mA/W. This study provides useful information for the development of optoelectronics based on ZnO.
关键词： Phototransistor,Sputter,Thin film transistor,Solution process,Zinc Oxide
更新于2025-09-10 09:29:36
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Fluorescence Properties of Tb-Doped ZnO Porous Network Thin Film Grown on Monocrystalline Silicon Substrate
摘要： This research presents a new perspective on optical biosensors based on zinc oxide nanoparticles. The widely known and successfully applied nanostructured material is modified by the dopant - the green phosphor Terbium, which embedded in the structure of zinc oxide and makes a significant contribution to the fluorescent response of the material in both the UV and visible spectral regions. The effect of various dopant concentrations on the fluorescence of nanostructures was studied; the nanostructures were examined by SEM.
关键词： fluorescence,biosensors,nanostructures,zinc oxide,terbium
更新于2025-09-10 09:29:36
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Photocatalytic response of Fe, Co, Ni doped ZnO based diluted magnetic semiconductors for spintronics applications
摘要： Novel attempts were made to prepare diluted magnetic semiconductors separately with 10 at.% each of Fe, Co and Ni doped ZnO by sol-gel method. The XRD analysis of the films detect wurtzite ZnO as the pure phase present in the synthesized films. The average particle size of 10 at.% Fe, Co, Ni doped and pristine ZnO derived films are found as 10.01 nm, 12.03 nm, 15.36 nm and 16.16 nm respectively. The absorbance spectra of the oxides reveal intrinsic band gap of ZnO, Fe2O3, CoO and NiO are 3.29 eV, 2.53 eV, 2.42 eV and 3.64 eV respectively. The near band edge absorbance of pure ZnO was recorded as about 377 nm (～3.29 eV) which shifts to lower wavelength with reduction in particle size in Ni, Co and Fe doped ZnO sample as the effect of quantum confinement. The PL spectra of the developed films reveal multiple peaks between 450 nm and 500 nm, on excitation wavelength at 370 nm, as the evidence of photochemical properties of the samples. Vibrating sample magnetometer analysis reveals 10 at.% Fe doped ZnO posses minimum value of squareness 0.118 and coersivity 177.738 Oe which prove it to be the best magnetic material among all four samples prepared. Raman spectra show evidence of phonon confinement for 10 at.% Fe doped ZnO sample by broadening of Eg, T2g and A1g peaks, which is not so prominent for other samples. In addition, the photochemical degradation reaction is maximum for 10 at.% Fe doped ZnO sample which proves to be most suitable material for optoelectronic devices.
关键词： Solar spin,Zinc oxide,Photocatalytic response,Diluted magnetic semiconductors,Phonon confinement
更新于2025-09-10 09:29:36
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Photoelectric Properties of Zinc Oxide Films Diffusion-Doped by Gallium and Lithium for Creation of Nonlinear Electric Elements
摘要： A technique for local diffusion doping of the certain areas of the ZnO film of donor (Ga) and acceptor (Li) impurities has been developed to produce the films with the topological pattern of doping regions. The diffusion process, electrophysical and photoelectric properties of diffusion-doped samples of the planar MSM structures based on the Al–ZnO–Al, Al–ZnO:Ga–Al and Al–ZnO:Li–Al with the metallic aluminum as contacts are investigated. It is shown that the diffusion introduction of the impurity of gallium suppresses the photosensitivity, and the diffusion introduction of lithium into the ZnO films increases the photosensitivity as compared to the undoped areas of the same film.
关键词： diffusion,donor,zinc oxide film,acceptor
更新于2025-09-10 09:29:36
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Effects of ultraviolet photon irradiation and subsequent thermal treatments on solution-processed amorphous indium gallium zinc oxide thin films
摘要： Effects of exposure to ultraviolet (UV) photons and thermal treatments on solution-processed amorphous indium gallium zinc oxide (a-IGZO) films were investigated by X-ray photoelectron spectroscopy (XPS) and photoluminescence (PL) spectroscopy. As a result, oxygen vacancies obviously become more abundant in the films sintered at 250 or 300 ?C by the exposure to 7.21 eV photons and less abundant by the subsequent thermal treatment at 250 ?C in air. The drain current also clearly becomes smaller in a thin film transistor fabricated using the IGZO film in a manner opposite to the abundance of oxygen vacancies. That is, the drain current becomes smaller by the UV irradiation and returns to the original high value by the subsequent thermal treatment. This indicates that oxygen vacancies act as trapping centers or scattering centers of electrons. In addition, the reversible change of the drain current with the cycle of UV irradiation and the thermal treatment opens the possibility of the use of the IGZO films as a UV sensor.
关键词： oxygen vacancies,amorphous indium gallium zinc oxide,thin film transistor,UV irradiation,thermal treatment
更新于2025-09-10 09:29:36