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Preparation and Photocatalytic Activity of Ag-Modified SnO2@TiO2 Core- Shell Composites
摘要： Photocatalytic degradation is an important method to mediate organic pollution in the environment. This article reports Ag-modified SnO2@TiO2 core-shell composite photocatalysts prepared via a hydrothermal method. The composite materials were characterized by X-ray diffraction, transmission electron microscopy, energy dispersive X-ray spectroscopy, thermogravimetry, X-ray photoelectron spectrometry, and UV-vis diffuse reflectance spectroscopy. The Ag modification and core structure in the composite enhanced the photocatalytic activity and stability of TiO2 for Rhodamine B degradation under visible light irradiation. The composite modified in 0.15 M AgNO3 showed an optimal level of photocatalytic activity, as it degraded 99.14% of Rhodamine B in 60 min while pure TiO2 only degraded 45.7% during the same time.
关键词： Hydrothermal method,Core-shell composites,Photocatalytic activity
更新于2025-09-16 10:30:52
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Fabrication of functionalized plasmonic Ag loaded Bi2O3/montmorillonite nanocomposites for efficient photocatalytic removal of antibiotics and organic dyes
摘要： From the viewpoint of practical application, the development of photocatalyst having strong light harvesting and effective charge separation as well as using abundant natural mineral as photocatalyst substrate would be very promising. In this work, a novel Ag loaded Bi2O3/montmorillonite nanocomposite has been successfully prepared by a facile thermal and impregnation methods for the first time to study its photocatalytic performance for aqueous pollutant decomposition under the visible light irradiation. Interestingly, the Ag loaded Bi2O3/montmorillonite nanocomposite presented excellent visible light induced photocatalytic activities for tetracycline (TC) antibiotic and RhB degradation, which is much superior over those of solely Bi2O3, montmorillonite and the corresponding composite. The superiority photocatalytic performance of Ag loaded Bi2O3/montmorillonite nanocomposite over other samples should be due to the improved visible light absorption, enlarged specific surface area and enhanced charge separation. In addition, the effect of different factors such as dosage of composite, pollutants concentration and pH of the pollutant solution on the photocatalytic activity of the composite was inspected. Finally, the possible photocatalytic mechanism of Ag loaded Bi2O3/montmorillonite nanocomposite towards pollutants was proposed in detail based on the trapping experiment and ESR test. The as-developed composite provides a new high efficiency of photocatalyst for potential applications in refinement antibiotic pollutants from wastewater.
关键词： Silver nanoparticle,Photocatalytic activity,Bismuth oxide,Montmorillonite,Mechanism
更新于2025-09-12 10:27:22
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A synthesis of graphene quantum dots/hollow TiO2 nanosphere composites for enhancing visible light photocatalytic activity
摘要： Given the versatility and value of the semiconductor composites for photocatalysis, we reported a new, friendly environment, high specific surface area material of the graphene quantum dots/hollow titanium dioxide nanosphere (GQDs/H-TiO2) composites which are synthesized through a simple hydrothermal method. GQDs (~ 5 nm) exhibit highly photoluminescent and widely visible light absorption properties. H-TiO2 has high surface area and abundant exposed active sites for photocatalysis. The research demonstrates that GQDs coupled on H-TiO2 can effectively enlarge the light absorption of the H-TiO2 to visible region (~ 650 nm) and enhance the electron–hole pair separation efficiency of GQDs/H-TiO2 composites owing to GQDs acting as an electron repository and electron transport bridge. In our delight, the photocurrent enhancement of newly prepared GQDs-3.0/H-TiO2 composite electrode was almost 3.5 times higher in comparison with that in pure H-TiO2 electrode at an applied voltage of 0.5 V using Na2SO4 (0.5 M) solution as the electrolyte. In addition, the photocatalytic activity of the prepared GQDs-3.0/H-TiO2 (96.9%) on the degradation of Rhodamine B (RhB) was also significantly enhanced compared with that of pure H-TiO2 (33.3%) after 180 min. The protocol is suitable not only for the GQDs-modified semiconductors photocatalysts but also provides further insights to apply GQDs to other energy conversion devices.
关键词： composites,graphene quantum dots,hollow TiO2 nanosphere,visible light photocatalytic activity
更新于2025-09-12 10:27:22
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Silver Quantum Dot Decorated 2D-SnO2 Nanoflakes for Photocatalytic Degradation of the Water Pollutant Rhodamine B
摘要： Decoration of 2D semiconductor structures with heterogeneous metal quantum dots has attracted considerable attention due to advanced optical, electrical, and catalytic properties that result from the large surface-to-volume ratio associated with these structures. Herein, we report on silver quantum dot decorated 2D SnO2 nano?akes for the photocatalytic abatement of water e?uents, the synthesis of which was achieved through a straightforward and mild hydrothermal procedure. The photocatalysts were systematically investigated using UV–Vis, XRD, electron microscopy (SEM, HR-TEM), EDX, XPS and FTIR. The photocatalytic activity of the nanostructures was evaluated for the abatement of water pollutant rhodamine B (RhB), under light irradiation. The mild hydrothermal synthesis (100°C) proved highly e?cient for the production of large scale Ag quantum dot (QD)/SnO2 nano?akes for a novel photocatalytic application. The decoration of SnO2 with Ag QDs signi?cantly enhances the synergetic charge transfer, which diminishes the photo-induced electron-hole reunion. Moreover, the plasmonic e?ect from Ag QDs and 2D-SnO2 structures acts as an electron tank to collect the photo-induced electrons, generating a Schottky barrier between the SnO2 structures and quantum dots. Overall, this resulted in a facile and e?cient degradation of RhB, with a rate double that of pristine SnO2.
关键词： silver quantum dots,2D-SnO2 nano?akes,rhodamine B,photocatalytic activity
更新于2025-09-12 10:27:22
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Synthesis, Characterization,and Photocatalytic activity of Silver nanoparticledoped Phosphomolybdic acid supportedZirconia
摘要： An ecofriendly solid acid catalyst was synthesized by impregnating phosphomolybdic acid on zirconia followed by doping with Silver nanoparticles to form composite. We report here, the synthesis, characterization and photocatalytic behavior of AgNPs doped Keggin Ions/ Zirconia which is synthesized by wet impregnation method. The resulting nanocomposite was characterized by X-ray diffraction analysis (XRD), Fourier transform infrared spectroscopy (FTIR) and UV-Visible spectroscopy. The photocatalytic activity of the catalyst was evaluated for the degradation of azo dye under the Visible light irradiation. In the photoreaction study, it is found that photocatalytic activity increases by doping the noble metal silver nanoparticles on PMA/ZrO2 surface to form the composite.
关键词： Phosphomolybdic acid,Zirconia,Methylene blue dye,Photocatalytic activity
更新于2025-09-12 10:27:22
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Enhanced NO2 gas-sensing properties of Au-Ag bimetal decorated MWCNTs/WO3 composite sensor under UV-LED irradiation
摘要： Novel NO2 gas sensors that were made of Ag, Au and Au-Ag bimetal particles modified composite of multi-walled carbon nanotubes/tungsten oxide (Ag/MWCNTs/WO3, Au/MWCNTs/WO3 and Au-Ag/MWCNTs/WO3) were fabricated for sensing ppb-level NO2 gas under ultraviolet light emitting diode (UV-LED) irradiation. The effects of Ag, Au and Au-Ag bimetal decoration and under UV-LED irradiation on the response of the Ag/MWCNTs/WO3, Au/MWCNTs/WO3 and Au-Ag/MWCNTs/WO3 sensors for sensing NO2 gas were studied. The gas-sensing properties in the detection of a low concentration of NO2 gas of the Au-Ag/MWCNTs/WO3 composite were superior to bare MWCNTs/WO3, Au/MWCNTs/WO3 and Ag/MWCNTs/WO3 under UV-LED irradiation. The Au-Ag/MWCNTs/WO3 composite sensor showed responses of 28–262 % at NO2 concentrations ranging from 100 to 500 ppb under UV-LED irradiation. These responses were 2–5 times higher than that of the bare MWCNTs/WO3 composite sensor at the same NO2 concentration range. The substantial improvement in the response of the bare MWCNTs/WO3 composite to NO2 gas by its decoration with Au-Ag bimetal particles may be attributed to the enhanced catalytically active sites and photocatalytic activity. A reasonable mechanism for enhancing sensitivity was proposed.
关键词： UV irradiation,NO2 gas sensor,Photocatalytic activity,Au-Ag bimetal
更新于2025-09-11 14:15:04
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Microwave-Assisted Synthesis of High-Energy Faceted TiO2 Nanocrystals Derived from Exfoliated Porous Metatitanic Acid Nanosheets with Improved Photocatalytic and Photovoltaic Performance
摘要： A facile one-pot microwave-assisted hydrothermal synthesis of rutile TiO2 quadrangular prisms with dominant {110} facets, anatase TiO2 nanorods and square nanoprisms with co-exposed {101}/[111] facets, anatase TiO2 nanorhombuses with co-exposed {101}/{010} facets, and anatase TiO2 nanospindles with dominant {010} facets were reported through the use of exfoliated porous metatitanic acid nanosheets as a precursor. The nanostructures and the formation reaction mechanism of the obtained rutile and anatase TiO2 nanocrystals from the delaminated nanosheets were investigated. The transformation from the exfoliated metatitanic nanosheets with distorted hexagonal cavities to TiO2 nanocrystals involved a dissolution reaction of the nanosheets, nucleation of the primary [TiO6]8? monomers, and the growth of rutile-type and anatase-type TiO2 nuclei during the microwave-assisted hydrothermal reaction. In addition, the photocatalytic activities of the as-prepared anatase nanocrystals were evaluated through the photocatalytic degradation of typical carcinogenic and mutagenic methyl orange (MO) under UV-light irradiation at a normal temperature and pressure. Furthermore, the dye-sensitized solar cell (DSSC) performance of the synthesized anatase TiO2 nanocrystals with various morphologies and crystal facets was also characterized. The {101}/[111]-faceted pH2.5-T175 nanocrystal showed the highest photocatalytic and photovoltaic performance compared to the other TiO2 samples, which could be attributed mainly to its minimum particle size and maximum specific surface area.
关键词： high-energy facets,photocatalytic activity,photovoltaic performance,anatase TiO2 nanocrystals
更新于2025-09-11 14:15:04
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Synergistic effects of CuO and Au nanodomains on Cu2O cubes for improving photocatalytic activity and stability
摘要： Cu2O is a promising photocatalyst, but it suffers from poor photocatalytic activity and stability, especially for Cu2O cubes. Herein, we report the deposition of CuO and Au nanodomains on Cu2O cubes to form dual surface heterostructures (HCs) to improve photocatalytic activity and stability. The apparent quantum efficiency of Au/CuO/Cu2O HCs was ca. 123 times that of pristine Cu2O. In addition, the Au/CuO/Cu2O HCs maintained nearly 80% of its original activity after eight cycles in contrast to five cycles for the Au/Cu2O material. Therefore, CuO and Au domains greatly improved the photocatalytic activity and stability of the Cu2O cubes due to the synergistic effect of the HCs.
关键词： Charge transfer,Sequential surface engineering,Photocatalytic activity,Stability,Cuprous oxide
更新于2025-09-11 14:15:04
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The mechanism of photocatalyst and the effects of co-doping CeO2 on refractive index and reflectivity from DFT calculation
摘要： In this paper, the structural, electronic and optical properties of (N, P), (N, S), (C, P) and (C, S) co-doped CeO2 are studied by using the method of density functional theory (DFT) + U method. The calculated lattice constant, the charge, the bond order, the cell volume and the bond length of CeO2 are consistent with previous experimental and theoretical results. For co-doped CeO2 systems, the calculated results show that the lattice constants, the bond order of CeeO as well as the cell volume increase, while the charge of Ce decrease. Due to co-doping, the energy gap (Eg) between valence band and conduction band becomes narrower than that of pure CeO2. Meanwhile, the electron structures of the co-doped CeO2 are changed, which may lead to transformation of optical properties. Nonmetallic atomic orbital (C 2p, N 2p, P 3p, S 3p) and metal atomic orbital (Ce 4f and 5d) are hybridized, except for the hybridization between Ce (4f and 5d) and O (2p). Compared with CeO2, Eg between Ce 4f and Ce 5d becomes smaller. Further, the optical absorption, refractive index and re?ectivity of them are investigated. The calculated results reveal that their absorption edges have a red shift. Co-doping enhances visible light photocatalytic activity, which is related to the transition of valence band → conduction band, and Ce 4f → Ce 5d. The co-doped CeO2 has high refractive index and re?ectivity. Therefore they may be becoming an important materials in single (or multilayered) optical coatings and optical re?ective pigments.
关键词： Refractive index,Density functional theory,Photocatalytic activity,Re?ectivity,Electronic transition
更新于2025-09-11 14:15:04
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Enhanced photocatalytic activity and stability of AgBr/BiOBr/graphene heterojunction for phenol degradation under visible light
摘要： In this work, we have reported synthesis of AgBr/BiOBr photocatalyst supported on graphene (Gr) using facile precipitation method. AgBr/BiOBr/Gr was characterized using various spectral techniques like FESEM, TEM, XRD, FTIR, XPS, Raman and PL analyses. AgBr/BiOBr/Gr had improved visible light absorption. PL studies indicated the reduction in recombination of photogenerated electron hole pair of AGBr/BiOBr/Gr. AFM analysis con?rmed the thickness of AGBr/BiOBr/Gr was less than 8.0 nm. The higher dispersibility of photocatalyst was ascertained by Tyndall effect. AgBr/BiOBr/Gr photocatalyst was effectively used for the photodegradation of phenol from simulated water. The phenol degradation process was remarkably in?uenced by adsorption process. The concurrent adsorption and photocatalytic was effective for degradation of phenol. The phenol was completely mineralized into CO2 and H2O in 6 h. The degradation process followed pseudo ?rst order kinetics. The results con?rmed that integration of AgBr/BiOBr with graphene caused an increase in photocatalytic activity due to reduced recombination of photogenerated electron hole pair and electron sink behavior of graphene for photogenerated electrons of BiOBr. AgBr/BiOBr/Gr photocatalyst displayed signi?cant stability and recyclability for ten catalytic cycles.
关键词： Enhanced photocatalytic activity,Recyclability,Phenol degradation,Graphene,AgBr/BiOBr,Heterojunction formation
更新于2025-09-11 14:15:04