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Self-generating CeVO4 as conductive channel within CeO2/CeVO4/V2O5 to induce Z-scheme-charge-transfer driven photocatalytic degradation coupled with hydrogen production
摘要： The construction of highly efficient Z-scheme photocatalytic system is regarded as a hot research topic in the fields of environmental remediation and renewable energy production. In this work, a novel Z-scheme CeO2/CeVO4/V2O5 photocatalyst is successfully prepared by using solid phase reaction method. The photocatalytic degradation of organic pollutant (Methylene Blue) with simultaneous hydrogen production is efficiently realized over the prepared Z-scheme CeO2/CeVO4/V2O5 photocatalysts under visible-light irradiation. The effects of treatment temperatures and treatment times of CeO2/V2O5 composite on the photocatalytic performance of Z-scheme CeO2/CeVO4/V2O5 photocatalyst are studied. The as-prepared Z-scheme CeO2/CeVO4/V2O5 (550-3) photocatalyst heat-treated at 550 °C for 3.0 h exhibits the highest photocatalytic performance. It can be ascribed to a moderate amount of CeVO4 nanoparticles generated between CeO2 and V2O5. The generated CeVO4 nanoparticles can be used as effective conductive channel to transfer the photo-generated carriers. At the same time, as redox reaction centers it can further accelerate the transfer of photo-generated electrons, effectively enhancing the separation efficiency of photo-generated electron and hole pairs. Furthermore, cyclic test demonstrates that the as-prepared Z-scheme CeO2/CeVO4/V2O5 (550-3) photocatalyst still maintains a high level of photocatalytic activity within five periods under the same conditions. Moreover, the related photocatalytic mechanism for degradation of organic pollutants with simultaneous hydrogen evolution over the Z-scheme CeO2/CeVO4/V2O5 (550-3) photocatalyst is proposed. Perhaps, this study affords a simple and novel method to design and develop next generation of highly efficient Z-scheme photocatalysts.
关键词： Conductive channel,Z-scheme CeO2/CeVO4/V2O5 photocatalyst,Solid phase reaction method,Simultaneous hydrogen evolution,Visible-light photocatalytic degradation
更新于2025-11-19 16:51:07
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Black phosphorous sensitized TiO <sub/>2</sub> mesocrystals photocatalyst for hydrogen evolution with visible and near-infrared light irradiation
摘要： Wide absorption from ultraviolet (UV) to near-infrared (NIR) region and enhanced charge separation are two main requirements for promising semiconductor photocatalysts. Here, we studied visible-NIR driven photocatalytic hydrogen evolution over black phosphorus nanosheets/TiO2 mesocrystals loaded with Pt heterostructure (BP NS/ Pt (3 wt%)/TMC TMC). BP NS/Pt (3 wt%)/TMC can harvest photons from UV to NIR and simultaneously has enhanced charge separation to increase the generation of electrons for photocatalytic reduction of water. BP NS/Pt (3 wt%)/TMC exhibited photocatalytic H2 evolution rates of 1.9 and 0.41 μmol h-1 under visible (λ> 420 nm (420-1800 nm)) and NIR (λ> 780 nm (780-1800 nm) irradiation, respectively, compared with 0.3 and 0.10 μmol h-1 for BP NS/Pt (3 wt%)/P25. Moreover, a comparative study was made to examine the effect of thickness of BP NS on the photocatalytic H2 evolution. Femtosecond time-resolved diffused reflectance spectroscopy (fs-TRDRS) was integrated together with photoelectrochemical measurement to shed the light on the importance of charge transfer and separation, confirming that decreasing the thickness of BP NS enhances electron injection from BP NS to TMC to increase the photocatalytic activity.
关键词： hydrogen evolution,Black phosphorus,visible-light photocatalyst,charge carriers dynamics,TiO2 mesocrystals,femtosecond time-resolved diffuse reflectance
更新于2025-11-19 16:51:07
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Enhancing photoluminescence of carbon quantum dots doped PVA films with randomly dispersed silica microspheres
摘要： As a kind of excellent photoluminescent material, carbon quantum dots have been extensively studied in many fields, including biomedical applications and optoelectronic devices. They have been dispersed in polymer matrices to form luminescent films which can be used in LEDs, displays, sensors, etc. Owing to the total internal reflection at the flat polymer/air interfaces, a significant portion of the emitted light are trapped and dissipated. In this paper, we fabricate free standing flexible PVA films with photoluminescent carbon quantum dots embedded in them. We disperse silica microspheres at the film surfaces to couple out the total internal reflection. The effects of sphere densities and diameters on the enhancement of photoluminescence are experimentally investigated with a homemade microscope. The enhancement of fluorescence intensity is as high as 1.83 when the film is fully covered by spheres of 0.86 μm diameter. It is worth noting that the light extraction originates from rather the scattering of individual spheres than the diffraction of ordered arrays. The mechanism of scattering is confirmed by numerical simulations. The simulated results show that the evanescent wave at the flat PVA/air interface can be effectively scattered out of the film.
关键词： silica microspheres,light extraction,photoluminescence,PVA films,carbon quantum dots
更新于2025-11-19 16:46:39
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[IEEE 2018 19th International Conference on Electronic Packaging Technology (ICEPT) - Shanghai (2018.8.8-2018.8.11)] 2018 19th International Conference on Electronic Packaging Technology (ICEPT) - A Synthetic Method for Extremely Stable Thin Film of CsPbBr<inf>3</inf> QDs and its Application on Light-emitting Diodes
摘要： The ability to be mixed with the polymers is very important for applications of perovskite quantum dots (QDs), such as in display, lighting and so on. Here, a method for fabricating a thin film composed of CsPbBr3 QDs and polydimethylsiloxane (PDMS) was reported. By using the ethyl acetate, a large number of ligands on the surface were removed and the combination with polymers can realize. Based on the thin film, an LED device was assembled and its luminous flux, luminous efficiency, color temperature and CIE color coordinates were measured. What’s more, the thin film revealed a splendid stability after being stored for 42 days without any protection, which show the broad prospects of it.
关键词： Inorganic perovskite quantum dots,Stability,Light-emitting diodes
更新于2025-11-19 16:46:39
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Photo-Controlled Release of Metal Ions Using Triazoline-Containing Amphiphilic Copolymers
摘要： Photo-controlled release that shows quick response and high spatial/temporal accuracy has become attractive given its potential applications for biomedicines. A few metal complexes are known for detoxification, sterilization, diagnosis and treatment of diseases; but, the encapsulation and control release of those metal ions using polymer micelles are challenging. We report an interesting photo-controlled release of metal ions via photo-responsible triazoline-containing amphiphilic polymers. Amphiphilic random copolymers of glycidyl methacrylate and oligo(ethylene oxide) methyl ether methacrylate were prepared through free radical copolymerization. The glycidyl pendants were converted to azide, followed by a 1,3-dipolar cycloaddition reaction to form triazoline with norbornene. The resulting random copolymers containing triazoline formed micelles with a critical micellar concentration (CMC) of 7.68×10-3 mg/mL. The triazoline moieties could coordinate to transition metal ions, e.g. Co2+, thus to encapsulate the metal ions to the core of micelles. Photo-induced denitrogenation of triazoline was able to disrupt the coordination of Co2+ and triazoline, therefore leading to the release of Co2+. Solution viscosity, UV-vis/NMR spectroscopy and TEM were used to show that the coordination and release of Co2+ ions were successful upon exposure to light. The photo-controlled release profile was found to be linearly dependent on the irradiation time, which is potentially useful for the delivery of essential ions in vivo.
关键词： Light responsive,Amphiphilic polymers,Micelles,Triazoline,Photo-controlled release
更新于2025-11-19 16:46:39
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Effect of Excitation Wavelength on Optical Performances of Quantum-Dot-Converted Light-Emitting Diode
摘要： Light-emitting diode (LED) combined with quantum dots (QDs) is an important candidate for next-generation high-quality semiconductor devices. However, the effect of the excitation wavelength on their optical performance has not been fully explored. In this study, green and red QDs are applied to LEDs of different excitation wavelengths from 365 to 455 nm. The blue light is recommended for exciting QDs from the perspective of energy utilization. However, QD LEDs excited at 365 nm have unique advantages in eliminating the original peaks from the LED chip. Moreover, the green or red light excited by ultraviolet light has an advantage in colorimetry. Even for the 455 nm LED with the highest QD concentration at 7.0 wt%, the color quality could not compete with the 365 nm LED with the lowest QD concentration at 0.2 wt%. A 117.5% (NTSC1953) color gamut could be obtained by the 365 nm-excited RGB system, which is 32.6% higher than by the 455 nm-excited solution, and this can help expand the color gamut of LED devices. Consequently, this study provides an understanding of the properties of QD-converted LEDs under different wavelength excitations, and offers a general guide to selecting a pumping source for QDs.
关键词： excitation wavelength,colorimetry,quantum dots,light-emitting diode
更新于2025-11-19 16:46:39
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Excitation energy transfer in the far-red absorbing violaxanthin/vaucheriaxanthin chlorophyll a complex from the eustigmatophyte alga FP5
摘要： This work highlights spectroscopic investigations on a new representative of photosynthetic antenna complexes in the LHC family, a putative violaxanthin/vaucheriaxanthin chlorophyll a (VCP) antenna complex from a freshwater Eustigmatophyte alga FP5. A representative VCP-like complex, named as VCP-B3 was studied with both static and time-resolved spectroscopies with the aim of obtaining a deeper understanding of excitation energy migration within the pigment array of the complex. Compared to other VCP representatives, the absorption spectrum of the VCP-B3 is strongly altered in the range of the chlorophyll a Qy band, and is substantially red-shifted with the longest wavelength absorption band at 707 nm at 77 K. VCP-B3 shows a moderate xanthophyll-to-chlorophyll a efficiency of excitation energy transfer in the 50–60% range, 20–30% lower from comparable VCP complexes from other organisms. Transient absorption studies accompanied by detailed data fitting and simulations support the idea that the xanthophylls that occupy the central part of the complex, complementary to luteins in the LHCII, are violaxanthins. Target analysis suggests that the primary route of xanthophyll-to-chlorophyll a energy transfer occurs via the xanthophyll S1 state.
关键词： Chlorophyll a,Light-harvesting complex,Transient absorption,Violaxanthin,Photosynthesis,Vaucheriaxanthin
更新于2025-11-19 16:46:39
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Effect of UV wavelength on humic acid degradation and disinfection by-product formation during the UV/chlorine process
摘要： The efficiency of the ultraviolet (UV)/chlorine process strongly depends on UV wavelength because chlorine photolysis and its subsequent radical formation are highly wavelength-dependent. This study compared the degradation of humic acid (HA) during the UV/chlorine process by low pressure mercury lamp (LPUV, 254 nm) and ultraviolet light-emitting diode (UV-LED, 275 and 310 nm). The results indicated that HA degradation followed the pseudo-first-order kinetics, and the fluence-based degradation rate constants (kobs) were significantly affected by UV wavelength and solution pH. HA degradation decreased greatly with increasing solution pH during the UV/chlorine process at 254 nm, while the opposite trend was observed at 275 and 310 nm. In the meantime, kobs decreased in the order of 275 nm > 254 nm > 310 nm at pH > 7.0. The changes of chlorine molar absorption coefficients at different UV wavelengths resulted in the variation of chlorine photodecay rates (kobs, chlorine), and the synergistic effects of kobs, chlorine and chlorine quantum yields (Φchlorine) affected HA reduction. The formation of disinfection by-products (DBPs) during the UV/chlorine process was also evaluated. A significant suppression on DBP formation and DBP-associated calculated theoretical cytotoxicity were observed at 275 nm high UV fluence and alkaline pHs. These findings in this study demonstrate that UV wavelength at 275 nm is more suitable for HA degradation by the UV/chlorine advanced oxidation process in practical applications.
关键词： Disinfection by-products,Ultraviolet light-emitting diode (UV-LED),UV/chlorine,Humic acid,Toxicity,UV wavelength
更新于2025-11-19 16:46:39
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Electrochemical capacitance-voltage profiling of nonuniformly doped GaAs heterostructures with SQWs and MQWs for LED applications
摘要： Light-emitting heterostructures with single and multiple GaAs/InGaAs quantum wells have been investigated by means of electrochemical capacitance-voltage (ECV) profiling. Capacitance-voltage characteristics were measured; concentration profiles of free charge carriers over the heterostructure depth as well as the intensity of quantum well filling by charge carriers were obtained. In heterostructures with a single quantum well (QW) we considered limitations of capacitance techniques for undoped QW profiling, which is situated near the metallurgic border of the p–n –junction. We made a detailed consideration of phenomena related to Debye smearing and we developed and analyzed the dependence of the space charge region width on the doping. Special attention was paid to investigation of the “blind” area. This was inspired by the practical problem from capacitance spectroscopy of semiconductors, when the researcher poses the task of obtaining a free charge carrier depth distribution profile as deep as possible in the space charge region, i.e. where the intensity of the electric field is maximum. Generally, the active QW of a LED heterostructure is placed deep in the space charge region, so reaching these regions is extremely important for practical problems. We present an evolution of capacitance-voltage characteristics during ECV profiling of nonuniformly doped p – n– heterostructures. For a heterostructure with multiple quantum wells we registered a response from 6 QWs.
关键词： capacitance-voltage profiling,heterostructure,quantum well,nonuniform doping,Electrochemical capacitance-voltage profiling,quantum dot,light-emitting diodes
更新于2025-11-14 17:28:48
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Surface decoration of BiOCl with BiVO<sub>4</sub> particles towards enhanced visible-light-driven photocatalytic performance
摘要： BiVO4/BiOCl p-n junctioned photocatalysts were synthesized by surface replacement of pre-synthesized BiOCl with BiVO4 via a hydrothermal route. BiVO4 particles were decorated on the surface of BiOCl, the structures of which were favored of maximizing absorption of visible light. The photocatalytic activity of the heterojunctioned composites were evaluated by degradation of Rhodamine B (RhB) dye under visible light illumination. The results indicated that the composites exhibited superior efficiencies for RhB photodegradation in comparison with pure BiOCl, BiVO4 and BiOCl/BiVO4 with similar compositions. The 30% BiVO4/BiOCl exhibited an optimal photocatalytic activity due to the combinative effects of large visible-light absorbance and carrier separation. Experiments on scavenging active intermediates demonstrated that the enhanced photoactivity was primarily attributed to the formation of p-n junction. An effective built-in electric field was formed by the interface between p-type BiOCl and n-type BiVO4, which promoted the efficient separation of photoinduced electron-hole pairs.
关键词： visible light absorption,BiVO4 decorated BiOCl,surface replacement,heterostructures,charge carrier separation
更新于2025-11-14 17:04:02