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Incorporation of silver ion on structural and optical characteristics of CeO2 nanoparticles: White LED applications
摘要： CeO2 and Ag incorporated CeO2 nanoparticles were prepared by the chemical co-precipitation method. The samples were analyzed by XRD, HR-TEM, FE-SEM, EDX, UV-vis, Photoluminescence, FTIR, and Photocatalytic studies. XRD results showed that Ag incorporation did not alter the structure and phase of pure CeO2 lattice. Crystallite size was reduced due to Ag ions substitution and these are good agreement with HR-TEM results. Particle size was measured as ~ 5-7 nm. EDAX and FTIR spectra confirmed the existence of elements as per the targeted stoichiometry. FE –SEM showed the surface morphology of samples and they possessed a spherical structure with surface smoothening as a function of Ag initial addition. UV- vis absorption peak intensity was increased for every increase of Ag concentration. Better optical transmittance was received for the Ag composition of 6 %. Blueshift was taken place for the incorporation of Ag ions in CeO2 host and the reason was discussed in terms of size effect and electron transition from band to band. Two peaks were received from Photoluminescence (PL) study that is one weak emission from the UV region strong emission from the red region. Red Peaks were shifted to a higher wavelength side against the addition of Ag. A fast degradation response was observed for Ag-doped CeO2 nanoparticles through photocatalytic study.
关键词： CeO2,photoluminescence,Ag,blue shift,nanoparticles
更新于2025-09-23 15:19:57
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Nitrogen-doped graphene-cerium oxide (NG-CeO <sub/>2</sub> ) photocatalyst for the photodegradation of methylene blue in waste water
摘要： This study shows a facile approach for the preparation of CeO2 nanoparticles decorated with porous nitrogen-doped graphene (NG) nanosheets for effective photocatalytic degradation of methylene blue (MB). NG nanosheets were first synthesized using a hydrothermal method and then nitrogen-doped graphene-cerium oxide (NG-CeO2) was prepared through mixing of cerium nitrate with different concentrations of NG under ultrasonication followed by hydrothermal treatment. The synthesized nanocomposites were characterized using X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), transmission electron microscopy (TEM), and field emission scanning electron microscopy (FE-SEM). The photocatalytic activity of the synthesized nanocomposites was analyzed against MB dye. Results showed that the nanocomposites of NG-CeO2 have an average particle size of 20 nm. The as-prepared NG-CeO2 nanocomposites exhibited outstanding photocatalytic activity for dye degradation under visible light irradiation, which could be attributed to synergistic effects between the NG nanosheets and CeO2. The quantum of photodegradation increases with the increase of the NG content in the nanocomposites.
关键词： nitrogen-doped graphene,CeO2,methylene blue,photodegradation
更新于2025-09-23 15:19:57
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Controllable synthesis of transition metal ion-doped CeO2 micro/nanostructures for improving photocatalytic performance
摘要： Ceria (CeO2) micro/nanostructures with various sizes and shapes were successfully synthesized by doping with a series of transition metal ions without any surfactant or template. The crystal structure, morphology, and photocatalytic performance of CeO2 and Co-, Zr-, Cu-doped CeO2 were characterized. The lattice parameters, which indicate the crystal structure distortion and change of Ce4+, were changed by incorporating a transition metal into the CeO2. Doping with transition metal ion could broaden the absorption range from ultraviolet to visible region and enhance the concentration of oxygen vacancies, which exhibited a significantly lower optical band than pure CeO2. The photocatalytic studies revealed that CeO2 with a spate of oxygen vacancies displayed a higher photocatalytic activity than pure CeO2 in degrading the organic pollutant rhodamine B (RhB). Furthermore, the O2? and ?OH radicals formed during photocatalysis process were revealed by means of nitrotetrazolium blue chloride (NBT) reduction method and a terephthalic acid (TA) fluorescence probe method, respectively, which discovers that radicals were crucial for the degradation of RhB. The H2-TPR confirmed that a small amount of transition metal ions significantly affected the oxidation state of the surface cations and oxygen vacancies. This study clearly reveals the effects of different transition metal ion dopants on the morphologies and photocatalytic performance of transition metal ion-doped CeO2 micro/nanostructures.
关键词： oxygen vacancy,CeO2,metal ion-doping,morphology,photocatalytic activity
更新于2025-09-23 15:19:57
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Sonochemical synthesis of novel ZnFe2O4/CeO2 heterojunction with highly enhanced visible light photocatalytic activity
摘要： An eco-friendly ZnFe2O4/CeO2 nanocomposites as visible light photocatalysts with different mole ratios were successfully fabricated by sonochemical method. The nanocomposites material was characterized various analytical techniques such as X-ray diffraction (XRD), UV–vis diffuse reflectance spectroscopy (DRS), fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and Brunauer-Emmett-Teller surface area analysis (BET). The synthesized ZnFe2O4/CeO2 nanocomposites were used to remove malachite green (MG) as a model organic pollution under visible light irradiation. The enhanced photocatalytic activity was described with the term was increased a light absorption intensity enable too appeared a bandgap present in the electron transfer, scavengers of the reactive species and charge prolonged photogenerated carriers. Results showed that the ZnFe2O4/CeO2 nanocomposite in a 0.5:0.5 mol ratio exhibited the superior photocatalytic activity towards wastewater treatment. The synthesized catalyst having capability for enhance photoactive nanocomposites open up a new opportunities in various areas in photocatalysis.
关键词： Photocatalytic degradation,Visible light,ZnFe2O4/CeO2 nanocomposites
更新于2025-09-19 17:15:36
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Enhanced superconducting properties of a YGBCO/Gd-CeO2/YGBCO tri-layer film deposited by pulsed laser deposition
摘要： To evaluate the inhibition of the REBa2Cu3O7-δ (REBCO, where RE is rare earth) film thickness effect, a series of Y0.5Gd0.5Ba2Cu3O7-δ(YGBCO)/interlayer/YGBCO tri-layer films with Gd-Cerium oxide (CeO2) film were prepared under different experimental conditions in this study. The results illustrate that the electric current from the top YGBCO layer could transmit to the bottom YGBCO layer by adding Gd into the CeO2 interlayer with the approximate thicknesses limits of 10 nm. For further increase the electric current carrying capacity, a series of YGBCO/Gd-CeO2/YGBCO tri-layers were fabricated under different oxygen partial pressures and laser energies. The better crystallinity, and texture, and the smoother surface levels completely eliminated the thickness effect. However, the samples’ superconductivity declined sharply at low laser energies. Because the Gd particles deposited on the substrate were fully oxidized, this led to particle disappearance in the interlayer film. Additionally, YGBCO samples with a Gd-CeO2 interlayer were more likely to be damaged than a pure YGBCO sample in the measurement process, which could be solved by increasing the Gd content in the CeO2+Gd target. Hence, by depositing a Gd-CeO2 interlayer, YGBCO tri-layer films with high superconductivity and low damageability were obtained.
关键词： Gd-CeO2 interlayer,laser energy,superconductivity,damageability,oxygen partial pressure
更新于2025-09-11 14:15:04
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Visible-light-driven CeO2/black phosphorus heterostructure with enhanced photocatalytic performance
摘要： CeO2/black phosphorus (BP) heterostructure nanocomposite was synthesized via a two-step assembly method. The structure and optical property of the prepared composites were characterized by X-ray diffraction, transmission electron microscopy, UV–Vis diffuse reflectance spectroscopy (UV–Vis), Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy. Photocatalytic degradation of bisphenol A (BPA) in simulated waste water was performed by using CeO2/BP nanocomposite as catalyst. Results indicated that the degradation rate of BPA reached 82.3% within 180 min, which was remarkably improved compared with pure CeO2 and BP due to the formation of indirect Z-scheme heterostructure intermediated by oxygen vacancies originated from CeO2. The unique heterostructure facilitated the charge transfer and preserved the high redox potential leading to improve the photocatalytic degradation performance.
关键词： photocatalytic degradation,heterostructure,bisphenol A,oxygen vacancies,CeO2/black phosphorus
更新于2025-09-10 09:29:36
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Fabrication of Thin Functional Films by Solution Aerosol Thermolysis (SAT)
摘要： The technique of air-pressurized solution spray pyrolysis was used to fabricate thin films of La0.75Sr0.25MnO3 (LSM) and CuO-CeO2 on dense YSZ substrates. These films are widely used in several applications such as high temperature ceramic electrochemical cells, membranes and sensors. The technique was tailored to produce films with differing morphologies and thicknesses in terms of applied substrate deposition temperatures. The droplet drying and decomposition kinetics is discussed as a function of substrate temperature, given the other processing parameters (i.e. nozzle to substrate distance, solution flow rate, air pressure/air flow rate and deposition time) constant. A graph-map is drawn containing morphology and quality of fabricated films in terms of substrate temperatures and concentration levels for this particular set of precursor salts in aqueous solutions. Within the deposition temperature range examined, film thicknesses were found to decrease with increasing substrate temperature along with a concomitant change in quality from irregular texture to smoother and of more uniform thickness. A maximum deposition temperature of about 280?C was identified for 0.025M concentration for both types of films which correlates quite well with the Leidenfrost point measured in the literature for solvents with boiling point less than 150?C.
关键词： YSZ substrates,spray pyrolysis,thin films,LSM,CuO-CeO2,solution aerosol thermolysis
更新于2025-09-10 09:29:36
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Applying facilely synthesized CuO/CeO <sub/>2</sub> photocatalyst to accelerate methylene blue degradation in hypersaline wastewater
摘要： Textile and dye effluents have strong color, unstable pH and COD, a lot of inorganic salt, and high biotoxicity. It is difficult and inefficient to remove dyes from high‐saline wastewater by traditional methods. In this study, a simple synthetic CuO/CeO2 photocatalyst is used to achieve high efficiency photodegradation of methylene blue in high salt wastewater. The p‐type CuO/n‐type CeO2 heterojunction photocatalyst is synthesized by a modified hydrothermal‐calcination method. The XRD and XPS reveal the successful synthesis of CuO/CeO2 composite. The SEM and TEM images show that the sample consists of large amounts of well‐dispersed CuO nanosphere loading on the CeO2 layers. DRS exhibits the absorption band (about 510 nm) and the band gap energy (2.43 eV) of the CuO/CeO2 composite. Compared with pure CuO, CeO2, and TiO2 (P25), the prepared CuO/CeO2 can increase the mineralization rate of MB by 18.19%~33.74%. More than 80% of MB can be effectively removed in the wastewater containing 5~80 g/L NaCl with a wide pH value range of 2.11~9.02, and the degradation processes follow the pseudofirst‐order reaction kinetics. Active species trapping experiments confirm that the degradation of methylene blue is mainly attributed to hydroxyl radical; besides, O2?? and hole (h+) also play important roles. Chlorine ions have dual effects in photocatalytic reactions. This work could provide a new approach to construct new heterojunction photocatalysts and a deeper insight for the treatment of hypersaline dye wastewater.
关键词： methylene blue,dye wastewater,hypersaline,UV/H2O2,CuO/CeO2,photocatalysis
更新于2025-09-10 09:29:36
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Redox Dynamics of Pd Supported on CeO <sub/>2</sub> -ZrO <sub/>2</sub> during Oxygen Storage/Release Cycles Analyzed by Time-Resolved <i>In Situ</i> Reflectance Spectroscopy
摘要： In situ time-resolved diffuse reflectance spectroscopy provided the redox dynamics of Pd nanoparticles supported on an oxygen storage material CeO2-ZrO2 (CZ) under lean/rich perturbation conditions. Because the reflectance at 450 nm is sensitive to the Pd oxidation state but is not affected by the redox of Ce3+/Ce4+ species of CZ, the real-time Pd redox can be monitored every second during oxygen storage/release in simulated engine combustion exhaust gas (CO–C3H6–NO–O2) corresponding to gasoline air-to-fuel ratios of 14.1 (rich) and 15.0 (lean). Although a large amount of O2 was stored by CZ upon the rich-to-lean switch, the rate of Pd oxidation during this event was found to be much more moderate compared to that with a reference catalyst, Pd/Al2O3. Because rapid oxygen uptake by CZ reduces the local O2 partial pressure near the surface, the oxidation of Pd should be retarded. This can preserve active metallic Pd and thus contribute to longer retention of high NO reduction efficiency even under the lean condition. However, the reduction of Pd oxide (PdO) upon reverse (lean-to-rich) switching occurred at a similar rate irrespective of the support material. The metallic Pd deposits near the interface with CZ promote the catalytic activation of reducing gases (CO and C3H6), resulting in significant oxygen release from CZ. The temperature dependence of the redox rate demonstrates that oxidation of metallic Pd to PdO is much slower than reduction over Pd/CZ, whereas oxidation is faster than reduction over Pd/Al2O3. The preservation of active metallic Pd under lean/rich perturbation conditions is another key role of the oxygen storage CZ co-catalyst.
关键词： CeO2-ZrO2,in situ diffuse reflectance spectroscopy,oxygen storage/release,redox dynamics,Pd nanoparticles
更新于2025-09-10 09:29:36
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Rational construction of direct Z-scheme doped perovskite/palygorskite nanocatalyst for photo-SCR removal of NO: Insight into the effect of Ce incorporation
摘要： V-Ti oxide catalyst has been widely employed in selective catalytic reduction (SCR) of NOx in industry. However, considerable cost and high reaction temperatures are commonly required. Alternatively, photo-SCR working at low temperature has attracted widespread interest. In the present work, Pr1(cid:1)xCexFeO3/palygorskite (Pal) nanocomposite was synthesized by an in situ sol-gel method. Results indicate that Pr1(cid:1)xCexFeO3 remain as a perovskite solid solution uniformly immobilized on the surface of Pal when x is less than 0.05. CeO2 co-precipitates with Pr1(cid:1)xCexFeO3 when x is beyond 0.05, leading to an enhanced charge separation induced by the formation of intimate direct Z-scheme heterostructure of Pr1(cid:1)xCexFeO3/CeO2, which is unraveled by the photoluminescence spectroscopy and Mott-Schottky analysis and further verified by the DFT calculations. Under visible light irradiation, the influence of the doping amount of Ce (from 0.05 to 0.5) on the NO conversion and N2 selectivity was investigated. The Pr0.7Ce0.3FeO3/Pal was found to achieve the highest NO conversion rate of 92% and 99% N2 selectivity. In addition, the SO2 and H2O resistance experiment show that the doping of Ce could benefit the formation of cerium sulphate which prevents NH3 from being sulfated by SO2 while Pal prevents the catalysts from being corroded by H2O, respectively.
关键词： Direct Z-scheme,Photo-SCR,Palygorskite,Denitrification,CeO2,Perovskite
更新于2025-09-10 09:29:36