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Facile fabrication of phosphorus-doped g-C3N4 exhibiting enhanced visible light photocatalytic degradation performance toward textile dye
摘要： Phosphorus-doped graphitic carbon nitride (P-g-C3N4) was facilely fabricated by in situ thermal copolymerization of urea and triphenylphosphine source materials. The P-g-C3N4 exhibited an enhanced photocatalytic performance than pristine g-C3N4 counterpart for the degradation of rhodamine B and acid blue D-2BR textile dye under visible light irradiation. X-ray diffraction (XRD), transmission electron microscopy (TEM), N2 adsorption-desorption isotherms, X-ray photoelectron spectra (XPS), and diffuse reflection spectroscopy (DRS) techniques were used to characterized the structure and property of P-g-C3N4 photocatalyst. The phosphorus doping enhanced visible light harvesting and surface area, but also substantially changed the electronic property of g-C3N4 material that could suppress the recombination of photogenerated charge carriers, and thus improved photocatalytic performance.
关键词： Textile dye,Porous photocatalyst,Visible light,Degradation,Phosphorus-doped g-C3N4
更新于2025-09-23 15:23:52
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Synthesis and characterization of a series of new green solar heat-reflective pigments: Cr-doped BiPO4 and its effect on the aging resistance of PMMA (Poly(methyl methacrylate))
摘要： A series of new green Cr-doped BiPO4 materials were synthesized by hydrothermal method and first used as solar heat-reflective pigments. XRD, FTIR, FE-SEM and HR-TEM analyses confirm that the phase structure was transformed from low-temperature monoclinic phase (LTMP) to hydrated hexagonal phase (HP), the particle size decreased and the morphology changed from irregular prism-shaped to rod-shaped, which all attributed to the incorporation of Cr3+ ions. Moreover, the valance of chromium ions was also confirmed by XPS. Color and ultraviolet-visible-near-infrared (UV–Vis–NIR) analysis indicate that different hues of green were obtained in these solid solutions and they possessed high NIR reflectance (> 83%) and solar reflectance (> 86%) in total NIR region. Meanwhile, the reason of decrease in NIR reflectance of doped samples was also analyzed, which mainly due to the decrease of free carrier concentration. TG-DTA and corrosion resistance tests prove that these pigments have excellent thermal and chemical stability. Compared with pure PMMA and the existing reports on pigmented PMMA, the NIR reflectance of PMMA pigmented with Cr-doped BiPO4 pigments have been greatly improved and have good coloring performance. The NIR solar reflectance of PMMA colored with Bi0.85Cr0.15PO4 in shortwave NIR region reaches up to 77.83%, an increase of nearly 52%. Heat aging test shows that Cr-doped BiPO4 pigments significantly improve the aging resistance of PMMA. In conclusion, these pigments have potential to become plastic colorants to increase the NIR reflectance and aging resistance of plastics.
关键词： Green pigments,Cr-doped BiPO4,Aging resistance,NIR reflectance,PMMA
更新于2025-09-23 15:23:52
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Enhancing visible light photocatalytic performance with N-doped TiO <sub/>2</sub> nanotube arrays assisted by H <sub/>2</sub> O <sub/>2</sub>
摘要： N-doped TiO2 nanotube arrays were prepared by an electrochemical anodization method and subsequent ammonia annealing. Microstructures, morphology, optical properties and photocatalytic properties of the N-doped TiO2 nanotube arrays were measured and analyzed. In the degradation of Acid Orange II(AO-II), the photocatalytic degradation efficiency of the N-doped TiO2 nanotube arrays assisted by H2O2 are 12 times, 2 times and 5 times higher than TiO2 nanotube arrays, TiO2 nanotube arrays assisted by H2O2 and H2O2, respectively. Experimental results show that the N-doped TiO2 nanotube arrays is a promising photocatalytic material for organic pollutant degradation under visible light, especially under the assistance of H2O2.
关键词： photocatalytic performance.,N-doped TiO2,H2O2,Electrochemical anodization
更新于2025-09-23 15:23:52
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Suitability of Raman Spectroscopy for Assessing Anisotropic Strain in Thin Films of Doped Ceria
摘要： A protocol for characterizing relaxation of anisotropic strain in thin films of 10 mol% Eu- or Sm-doped ceria is described. The method is based on comparison of Raman spectra and X-ray diffraction patterns from substrate-supported films, displaying in-plane compressive strain (initial state), with analogous data from 2 mm diameter self-supported films (i.e., membranes), prepared by partial substrate removal (final state). These membranes are found to be relaxed, i.e., approximately unstrained, but with increased unit cell volume. The effective (i.e., 2-state) Grüneisen parameter of the F2g Raman active mode for these films is calculated to be 0.4 ± 0.1, which is ≈30% of the literature value for the corresponding ceramics under isostatic pressure. On this basis, it is found that the observed red-shift of the F2g mode frequency following isothermal strain relaxation of the doped ceria thin films cannot be determined solely by the increase in average unit cell volume. The study presented here may shed light on the suitability of Raman spectroscopy as a technique for characterizing strain in lanthanide-doped ceria thin films.
关键词： doped ceria,Raman spectroscopy,Grüneisen parameter,anelastic relaxation
更新于2025-09-23 15:23:52
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Molecular Functionalization of Planar Nanocrystalline and Porous Nanostructured Diamond to Form an Interface with Newborn and Adult Neurons
摘要： This article examines the ability of newly developed nanostructured porous boron-doped diamond (BDD) to form an interface with neural cells and the role of molecular functionalization by a polymer on this interface. Due to its high stability, biocompatibility, and electrical properties, BDD is a promising material for construction of neuroelectrodes. Nanostructuring and an increase in the surface specific area can further improve the sensitivity and performance of such electrodes. Here, porous BDD prepared in a multistep diamond deposition on a porous template consisting of a polymer and electrospun SiO2 fibers is examined. This work shows that this new material is biocompatible and does not exhibit any cytotoxicity on fibroblast cell lines. Further, this work shows that porous BDD supports regeneration of newborn and adult neurons when functionalized with poly-L-lysine.
关键词： nanocrystalline diamond,boron-doped diamond,enhanced surface area,neural interface,chemical functionalization
更新于2025-09-23 15:23:52
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A Comparative Study of Gas Sensing Properties of Tungsten Oxide, Tin Oxide and Tin-Doped Tungsten Oxide Thin Films for Acetone Gas Detection
摘要： Nowadays, various metal oxide thin films have been used for the purpose of gas sensing. This research depicts a comparison of gas sensing properties among four different metal oxide thin films, namely, tungsten dioxide (WO2), tungsten trioxide (WO3), tin oxide (SnO2) and tin doped tungsten trioxide (Sn-doped WO3), for detecting acetone gas. Each metal oxide thin film was subjected to acetone gas flow of various concentrations and the corresponding changes in resistance were calculated. Characterizations such as x-ray diffraction (XRD), scanning electron microscopy (SEM), atomic force microscopy (AFM), and gas sensing characterization for recording resistance changes have been performed. Each film was annealed at different temperatures for 1 h (WO2 and WO3 at 500°C, SnO2 at 300°C and Sn-doped WO3 at 400°C) so as to achieve an optimum grain size for sensing. The XRD patterns reveal formation of an orthorhombic phase of WO2, hexagonal phase of WO3 and orthorhombic phase of SnO2. AFM and SEM depict clear images of grain boundaries on the film. SnO2 has been found to be the best thin film for sensing acetone gas. Operational optimum temperature for sensing acetone gas has been calculated for each thin film (260°C for WO2, 220°C for WO3, 360°C for SnO2 and 300°C for Sn-doped WO3). It can detect a very low concentration of 1.5 ppm acetone gas with a good resistance response change of 30%. Various concentrations of acetone gas, namely, 1.5 ppm, 3 ppm, 5 ppm, 7 ppm, 10 ppm, 15 ppm and 20 ppm, have been detected using these metal oxide thin films, and thus the comparison has been made. The response time for SnO2 is approximately 3 min and recovery time is approximately 4 min.
关键词： tungsten oxide,acetone gas detection,topography,tin oxide,Metal oxide thin films,surface metrology,gas sensing,tin-doped tungsten oxide
更新于2025-09-23 15:23:52
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Variable-range-hopping conduction and polaron dielectric relaxation in Cu and Nb co-doped BaTiO3
摘要： BaTi0.7(Cu0.1Nb0.2)O3 ceramic was prepared using a solid-state method and its structure, valence states, conduction mechanism and dielectric properties were investigated in detail. A fine-grained microstructure and a distorted pseudo-cubic perovskite structure were confirmed by scanning electron microscopy, X-ray diffraction analysis and Raman spectroscopy. X-ray photoelectron spectroscopy analysis suggested that Cu in BaTi0.7(Cu0.1Nb0.2)O3 was polyvalent but the valence states of Ti and Nb were invariable. Mott’s variable-range-hopping (VRH) conduction was observed. The two colossal dielectric constant plateaus in low- and high-temperature ranges were ascribed to the electrode and grain boundary responses, respectively. The VRH model described the low-temperature relaxation well, indicating that the dielectric relaxation was a polaron relaxation rather than Maxwell–Wagner type. Both grain and grain boundary resistances were well fitted by the VRH model, suggesting that the VRH mechanism was tenable in both grain and grain boundaries. The electron paramagnetic resonance signal was ascribed to Cu ions, and the linewidth showed a linear relationship with T?1/4, corresponding to the charge transfer between different valence via Cu+-O-Cu2+ and Cu2+-O-Cu3+ paths. The hopping of carriers was also responsible for the conduction and polaron dielectric relaxations.
关键词： Variable-range-hopping conduction,Electron paramagnetic resonance.,Dielectric relaxation,Cu and Nb co-doped BaTiO3
更新于2025-09-23 15:23:52
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Optimization of a supercontinuum source based on tapered ordinary fibers
摘要： In this paper the generation of visible spectrum via optimized supercontinuum generation (SCG) in tapered ordinary fibers by ultrashort laser pulses is presented. The tunability of the visible part of the spectra is achieved by changing the pump pulse duration during operation. The optimization of the SCG is carried out by the investigation of the taper geometry with the emphasis on the downtapering section length. Its increase is found to be correlated to higher intensity in the visible part of the spectra. This is further supported by the results on spectra evolution before it enters the taper waist where an important transfer of the pump power to the shorter wavelengths is found.
关键词： fiber lasers,ytterbium-doped fiber amplifiers,supercontinuum generation
更新于2025-09-23 15:23:52
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Influences of sol-gel progress on luminescent properties of Li <sub/>1.0</sub> Nb <sub/>0.6</sub> Ti <sub/>0.5</sub> O <sub/>3</sub> :Eu <sup>3+</sup> red phosphor
摘要： Li1.0Nb0.6Ti0.5O3:3wt.%Eu3+ red phosphor was synthesized by sol-gel method. The influences of the pH value and the citric acid(CA)/ metal cations(M) ratio on the luminescent properties of the samples were discussed. The properties of the samples were characterized by X-ray diffraction(XRD) and photoluminescence spectroscopy, respectively. The results showed that the samples were consist of “M- phase”. Under the 466nm excitation, the orange emission at 592nm and the red emission at 612nm could be observed. The emission intensity increased with the increasing of pH value firstly and then decreased. The optimum pH value was 5.5. Moreover, the emission intensity decreased with the increasing of CA/M ratio. The relatively high emission intensity of the sample could be obtained when the CA/M was 3:1. Emission spectra and CIE coordinate of Li1.0Nb0.6Ti0.5O3:3wt.% Eu3+ were superior to commercial red phosphor Y2O3:Eu3+,which showed the red phosphor could have potential application in the White-LED field.
关键词： the red phosphor,Eu3+-doped,emission spectrum,Sol-gel method
更新于2025-09-23 15:23:52
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Enhancement of multi-photon Raman scattering and photoluminescence emission from Li-doped ZnO nanowires
摘要： Uniform Li-doped ZnO nanowires have been fabricated by thermal evaporation method. The ZnO formation and the Li incorporation have been discussed and the formation path of preparation products has also been explained in terms of the stability of Zn and Li vapor in an aerobic atmosphere. The strongest vibration mode at 437.2 cm?1 in the multi-photon Raman scattering of the as-prepared products at room temperature indicates that the Li-doped ZnO nanowires still keep the hexagonal (wurtzite) structure. Raman spectra of Li-doped ZnO with different doping concentrations confirm that the variation of Raman peaks in the range of 550 cm?1～650 cm?1 is caused by the doping of lithium. The photoluminescence property at room temperature shows a blue-shift compared with undoped ZnO in the ultraviolet region. The Gauss fitting analyzed results indicate that the broad-band is composed of one green luminescence (GL) band, one yellow luminescence (YL) band, and one red luminescence (RL) band, respectively. The GL (2.447 eV) could be attributed to the singly ionized oxygen vacancies. The origin of the YL (2.245 eV) could be assigned to the transition of an electron from the conduction band (or a shallow donor) to the Li acceptor level. The RL (1.977 eV) could be assigned to the transitions between a shallow donor (at low temperature) or the conduction band (at higher temperature). Furthermore, the luminescence spectra at low temperature confirm the increase of defect levels like oxygen vacancies.
关键词： li-doped ZnO nanowires,formation process,photoluminescence,multi-photon raman scattering
更新于2025-09-23 15:23:52