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Investigation of structural, optical and electrical properties of transition metal oxide semiconductor CdO ZnO nanocomposite and its effective role in the removal of water contaminants
摘要： In this technological era as the usage and development of technology is on the rise we encounter serious repercussions of pollutions in both drinking and daily usage of water. Nanocomposite of Cadmium Oxide and Zinc Oxide (CdO-ZnO) has the property of alienating the pollutants from the water. A conventional hydrothermal method was adapted for the preparation of nanocomposite of CdO-ZnO from their respective metal acetate dihydrates and NaOH. Structural and morphological analysis by electron beam diffraction technique reveals the formation of unique nanorod with spherical morphology of the synthesized particle. Williamson-Hall method was used to find the crystallite size and the lattice strain. Fourier transforms infrared (FTIR) spectroscopy further confirmed the stretching and vibration of chemical bonds of the materials. The study of electronic transitions within the material was portrayed with UV-Vis absorption spectrum and the obtained energy gap is 3.99 eV. A thorough investigation of temperature dependent electrical properties of CdO-ZnO nanocomposite was carried out in the frequency range from 50 Hz to 5 MHz. Studies revealed that the composite material is responsible for higher photocatalytic performance under the irradiation of UV photon. The high photocatalytic activity was originated from superoxide O2? radicals due to the efficient trapping of photogenerated electrons in CdO by ZnO.
关键词： Zinc Oxide,Williamson-Hall method,Photocatalytic Activity,Cadmium Oxide,Electron Beam Diffraction
更新于2025-09-10 09:29:36
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Effect of pH Adjustment on Hydrothermal Synthesis of Aluminum Doped Zinc Oxide
摘要： Aluminum doped zinc oxide (AZO) was synthesized with various pH adjustments reagent (ammonia, TMAH, TEAH and TPAH) by hydrothermal reaction. Regardless of the pH adjustment, the main product of the synthesized powders with 5?mol% Al was zinc oxide. However, the diffraction peaks of gahnite (ZnAl2O4) were detected in the sample prepared from the precursor solutions with TMAH, TEAH and TPAH as pH adjustment. The excellent absorption property in near-infrared (NIR) region was obtained in the synthesized powder with about 2?mol% Al using ammonia. Based on these results, the initial state of Zn and Al ion in precursor solution is thought to affect the crystal phase of the product in hydrothermal synthesis. The NIR absorption property was highly enhanced by using urea as the pH-shift reagent during hydrothermal reaction process.
关键词： pH adjustment,Near-infrared reflectance,Hydrothermal synthesis,Aluminum doped zinc oxide
更新于2025-09-10 09:29:36
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Exposed facet dependent stability of ZnO micro/nano crystals as a photocatalyst
摘要： ZnO micro/nanocrystals with small size and more exposed high-surface-energy facets usually exhibit better photocatalytic properties. However, the stability of ZnO micro/nanocrystals used as a photocatalyst is always ignored. In this work, ZnO micro/nanocrystals with di?erent percentages of exposed (0 0 0 1) facets were employed as a photocatalyst in the degradation of methylene blue (MB) and their stability dependent on the exposed facets and grain size was discussed in detail. The higher percentages of exposed (0 0 0 1) facets can be obtained at a larger volume ratio of water/methanol (H2O/CH3OH) in the chemical bath method. It was found that ZnO micro/nanocrystals with a higher percentage of exposed (0 0 0 1) facets showed larger changes in the exposed (0 0 0 1) and (0 0 0 ?1) facets after their photodegradation of MB in aqueous solution, indicating a poor stability, although they displayed a better photocatalytic performance. Interestingly, ZnO nanocrystals with small size exhibited no obvious changes in their shape after their application as a photocatalyst. In this sense, exposed facets played more important roles in the stability of ZnO micro/nanocrystals than crystal size. This may be because that the Zn and O atoms in the exposed (0 0 0 1) and (0 0 0 ?1) facets preferred to be participated in the photocatalytic reaction and then formed Zn2+ ions and oxygen species in the solution after the reaction. Therefore, this work can provide a new insight into the stability of metal oxide micro/nanocrystals as photocatalysts.
关键词： Photocatalysis,Zinc oxide,Stability,Exposed facets,Grain size
更新于2025-09-10 09:29:36
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Low-Voltage, Flexible InGaZnO Thin-Film Transistors Gated with Solution-Processed, Ultra-Thin AlxOy
摘要： Indium-gallium-zinc-oxide thin-film transistors (TFTs) gated with solution-processed, ultra-thin AlxOy have been fabricated on a plastic substrate. The effects of bending on the gate dielectric leakage current density and capacitance density have been studied. The devices show a low operating voltage of less than 1 V, a high current on/off ratio > 105 and a low subthreshold swing < 90 mV/dec. The devices maintain their high performance even when flexed to a curvature radius of 11 mm. As a result, such devices possess a great potential for low-power, flexible electronics.
关键词： 1 V operation,thin-film transistors (TFTs),plastic substrate,Indium-gallium-zinc-oxide
更新于2025-09-10 09:29:36
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ZnO Quantum Dots Modified by pH-Activated Charge-Reversal Polymer for Tumor Targeted Drug Delivery
摘要： In this paper, we reported a pH responsive nano drug delivery system (NDDS) based on ZnO quantum dots (QDs) for controlled release of drugs. Zwitterionic poly(carboxybetaine methacrylate) (PCBMA) and poly(2-(dimethylamino) ethyl methacrylate) (PDMAEMA) were introduced to modify ZnO QDs, which can help enhance water stability, increase blood circulation time, and promote endocytosis. After tuning of PCBMA/PDMAEMA ratios, the ZnO@P(CBMA-co-DMAEMA) nanoplatform shows a sensitive switch from strong protein adsorption resistance (with negatively charged surface) at physiological pH to strong adhesion to tumor cell membranes (with positively charged surface) at the slightly acidic extracellular pH of tumors. Anti-cancer drug, Doxorubicin (DOX), molecules were demonstrated to be successfully loaded to ZnO@P(CBMA-co-DMAEMA) with a relatively large drug loading content (24.6%). In addition, ZnO@P(CBMA-co-DMAEMA) loaded with DOX can achieve lysosomal acid degradation and release of DOX after endocytosis by tumor cells, resulting in synergistic treatment of cancer, which is attributed to a combination of the anticancer effect of Zn2+ and DOX.
关键词： Zinc oxide quantum dots (ZnO QDs),poly(2-(dimethylamino) ethyl methacrylate) (PDMAEMA),drug delivery,poly(carboxybetaine methacrylate) (PCBMA)
更新于2025-09-10 09:29:36
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Zn-Free MOFs like MIL-53(Al) and MIL-125(Ti) for the preparation of defect-rich, ultrafine ZnO nanosheets with high photocatalytic performance
摘要： Metal organic frameworks (MOFs) are exploited in many applications of materials science and very recently were investigated as precursors or reagents for material synthesis. In a new way different from previous approaches, here we introduce for the first time the synthesis of metal oxide MxOy in the presence of M-free MOF acting partially as a sacrificial template and as a provider of doping metal atom. We demonstrate this approach in the case of ZnO prepared by a simple hydrothermal method in the presence of a Zn-free MOF like MIL-53(Al) or MIL-125(Ti). The resulting ZnO show low content of Al or Ti < 2% and properties are significantly different depending on whether MIL-53(Al) or MIL-125(Ti) are used or if no MOF is present. The nature and presence of MOF has different major effects on the morphology, the specific surface area of as prepared ZnO and also on the oxygen defects in its crystal structure. Corroborating the XPS, UV-Vis DRS, PL, EPR and DFT studies evidence the role of such O-defects on band gap narrowing for samples calcined at 400°C. These exhibit high efficiency in photodegradation of methyl orange (MO) compared to ZnO prepared in MOF-free conditions or previous literatures. The kinetics of MO degradation is different depending on the morphology, the specific surface and oxygen defects. The present data open the door to a new approach of the synthesis of metal oxides and a control of their properties
关键词： Oxygen defects,Zinc oxide,MOFs,Template,Photocatalysis
更新于2025-09-10 09:29:36
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Enhanced photocatalytic activity and photocurrent properties of plasma-synthesized indium-doped zinc oxide nanopowder
摘要： Zinc oxide and indium-doped zinc oxide (IZO) nanopowders (wurtzite crystal phase) were synthesized by plasma-assisted chemical vapor synthesis route. In this method, the injected precursors were vaporized in the plasma flame, followed by vapor-phase reaction and subsequent quenching of the vaporized materials, resulting in the formation of nanoparticles. The amount of indium nitrate was varied to obtain 4 at. % and 8 at. % indium incorporated in zinc oxide, designated as ‘IZO1’ and ‘IZO2’, respectively. UV–visible absorbance spectra of the product showed a redshift in the spectra with increasing doping amount of indium. Photocatalytic properties of ZnO and IZO nanoparticles were evaluated using the degradation of methylene blue (MB) under ultraviolet irradiation, and the kinetic analyses indicated that the photodegradation followed pseudo-first order kinetics. In addition, IZO1 nanoparticles exhibited superior photocatalytic activity to ZnO and IZO2 nanoparticles, and the enhancement was attributed to the low recombination rate of photogenerated charge carriers. The major role of defect concentrations (oxygen vacancies) toward MB degradation was also analyzed by Raman and XPS spectra. The effect of scavengers in the photodegradation process indicated that h+ and O2? were the main oxidant species involved in the degradation process. A mechanism of photodegradation process in IZO was proposed based on Mulliken electronegativity approach. Enhanced photocurrent density was obtained in IZO1, and the electrochemical impedance spectroscopy (EIS) results also pointed to an enhanced separation efficiency of electrons and holes at a lower indium doping amount as in IZO1.
关键词： ZnO,Plasma synthesis,IZO,Photocatalysis,Photocurrent,Indium-doped zinc oxide
更新于2025-09-10 09:29:36
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Three-Mode Modulation Electrochromic Device with High Energy Efficiency for Windows of Buildings Located in Continental Climatic Regions
摘要： A sustainable use of energy in buildings demands energy-efficient windows. A new design concept for electrochromic (EC) smart windows, easy to implement at the industrial level, is introduced here. It enables simultaneous control of visible and near-infrared (NIR) solar radiation, thus contributing to reduce heating and cooling loads especially in buildings located in areas experiencing wide daily temperature ranges. The EC device comprises amorphous indium zinc oxide, a conducting oxide transparent in the visible and NIR spectral regions, as nonactive layer, and a sol–gel protonic ionic liquid-doped di-ureasil electrolyte displaying high transparency and proton conductivity. The device offers three voltage-operated modes: bright hot (+3.0 V: transmittances of 70/83% at 555/1000 nm), semi-bright warm (?2.0 V: transmittances of 37/35% at 555/1000 nm), and dark cold (?2.5 V: transmittances of 6/4% at 555/1000 nm). Its main figures of merit are: high switching efficiency (transmittance variations of 64/79% at 555/1000 nm), high optical density modulation (1.1/1.3 at 555/1000 nm), high optical contrast ratio in the visible region (lightness variation of ≈43), good cycling stability, and unprecedented coloration efficiency (?12538/?14818 cm2 C?1 and +2901/+3428 cm2 C?1 at 555/1000 nm), outstanding optical memory (transmittance variation loss of only 24% more than 4 months after coloration), and self-healing ability following mechanical stress.
关键词： di-ureasil hybrid,N-butylimidazolium trifluoromethanesulfonate,visible- and NIR-controlled electrochromic devices,amorphous indium zinc oxide,energy-efficient smart windows for buildings
更新于2025-09-10 09:29:36
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The effects of gadolinium doping on the structural, morphological, optical, and photoluminescence properties of zinc oxide nanoparticles prepared by co-precipitation method
摘要： Pure and gadolinium (Gd)-doped zinc oxide (ZnO) nanoparticles were prepared by co-precipitation method. The EDS analysis confirmed the presence of Gd3+ ions in ZnO lattice. The X-ray diffraction measurement indicated the formation of hexagonal wurtzite structure for both pure and Gd-doped ZnO nanoparticles. The structural parameters of nanoparticles such as lattice constant, crystallite size, dislocation density, micro strain and other lattice parameters were calculated from XRD data. FESEM images of nanoparticles showed that the grain morphology of nanoparticles tends to hexagonal form by introducing Gd3+ ions into the ZnO lattice. The presence of functional groups and chemical bonding attributed to ZnO was confirmed by FT-IR measurement. The optical properties of nanoparticles were investigated by UV–Vis spectroscopy. The UV–Vis absorbance spectra, for Gd-doped samples, illustrated a blue shift by increasing Gd concentration. Also, the band gap of nanoparticles increased by increasing Gd concentration. The photoluminescence spectra of Gd-doped nanoparticles showed that the intensity of green luminescence increases by substitution of Gd3+ ions into the ZnO lattice attributed to the oxygen vacancies.
关键词： structural properties,morphological properties,co-precipitation method,gadolinium doping,zinc oxide nanoparticles,optical properties,photoluminescence properties
更新于2025-09-10 09:29:36
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Synthesis of novel ZnO/carbon xerogel composites: Effect of carbon content and calcination temperature on their structural and photocatalytic properties
摘要： This paper reports the development of new ZnO/carbon xerogel composites (XZn w) for photocatalytic applications. The use of black wattle tannin as a precursor to the carbon xerogel aimed at reducing costs and environmental impacts. The composites were characterized by di?use re?ectance spectroscopy (DRS), BET surface area, scanning electron microscopy (FEG-SEM), X-ray photoelectron spectroscopy (XPS), energy dispersive spectroscopy (EDS), infrared spectroscopy (IR), and X-ray di?raction (XRD). The photocatalytic performance of the materials was evaluated in the decomposition process of methylene blue, a known toxic pollutant. The impacts of the catalyst dosage and calcination temperature on the photocatalytic process were also examined systematically. The X-ray pro?les of the XZn w evidenced the existence of the hexagonal structure of the zinc oxide (wurtzite) in the composites. The XPS and XRD analyses con?rmed the incorporation of carbon in the zinc oxide crystalline structure. The higher carbon content resulted in a larger surface area. All composites presented the ability to absorb radiation in less energetic wavelengths, contrary to pure zinc oxide that only absorbs radiation of wavelengths below 420 nm. The optimal dosage and calcination temperature were found to be 0.2 g L?1 and 300 °C. All the developed composites displayed signi?cant photocatalytic activities in the decomposition of methylene blue under both visible and solar light. The composites had superior photocatalytic e?ciency under visible light when compared to pure zinc oxide. The XZn 0.5 presented the best degradation e?ciency under visible radiation. All materials presented similar photocatalytic responses under solar light, evidencing the synergy between the carbon xerogel and the zinc oxide. The photocatalytic mechanism was evaluated by trapping experiments to be mainly controlled by the electron vacancies that are generated during the photoexcitation of the composites.
关键词： Zinc oxide,Methylene blue,Carbon xerogel,Tannin,Photocatalysis
更新于2025-09-10 09:29:36