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Micro/nanoscale mesoporous Nb2O5 particles: Effect of synthesis conditions and doping with N, C, or S on their properties
摘要： A simple methodology was designed to obtain mesoporous niobium pentoxide (Nb2O5) solids functionalized with nitrogen, carbon, or sulfur. Dopant precursors were urea (N), citric acid (C) and thiourea (S). The doped solids were characterized using IR, Raman and diffuse reflectance UV–Vis spectroscopies, powder X-ray diffraction, adsorption–desorption isotherms, transmission electron and scanning electron microscopies. Depending on the amount of surfactant (cetyltrimethyl ammonium bromide — CTAB) used during synthesis, the solid presented mainly an orthorhombic crystal structure or an amorphous phase (for the sample with 0.25 mol/L CTAB). The adsorption–desorption isotherms of the synthesized solids showed hysteresis loops ( H1 andH4 types) characteristic of mesoporous solids, while transmission electron micrographs showed a disordered structure of pore channels known as ‘‘wormholes’’. There was considerable interaction between the dopant anion (mainly N and S) and the solid surface, generating new surface chemical species that clogged the pores, reducing specific surface and pore volume. The doped mesoporous Nb2O5 materials were polycrystalline, formed by primary monocrystalline particles of nanometric size (10–20 nm). Doping with N, C and S caused an important effect on the absorption of visible light, reducing the band gap energy value to 2.95 eV when doped with N, and to ～2.8 eV with S, relative to that of the undoped sample (3.03 eV). This result is important considering the potential use of mesoporous Nb2O5 materials in photocatalytic processes.
关键词： N, C and S dopants,Synthesis,Nanomaterials,Characterization,Mesoporous Nb2O5
更新于2025-09-10 09:29:36
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A green one-pot approach for mesoporous g-C3N4 nanosheets with in situ sodium doping for enhanced photocatalytic hydrogen evolution
摘要： Synchronous nano-structuring and element-doping of g-C3N4 were realized via a green one-pot approach to improve its photocatalytic activity. Na-doped mesoporous g-C3N4 nanosheets of ~5 nm in thickness were facilely synthesized by calcining a mixture of dicyandiamide and sodium chloride. NaCl not only serves as a con?ning-reactor to con?ne the growth of g-C3N4 into mesoporous nanosheets, but also acts as a sodium source for Na-doping. The nanosheets own greater speci?c surface area, stronger optical absorption and lower recombination of photo-induced electron-hole pairs than bulk g-C3N4, and exhibit an excellent visible-light photocatalytic hydrogen evolution ef?ciency which is about 13 times that of bulk g-C3N4. Moreover, the thermostable and hydrosoluble NaCl is simply removed and recycled by water and then directly reused in a new synthesis, making the process to be environmental-friendly and sustainable.
关键词： g-C3N4,Sodium chloride,Photocatalytic hydrogen evolution,Sodium doping,Mesoporous nanosheet
更新于2025-09-10 09:29:36
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Furfural-Mediated Synthesis of Mesoporous Ti <sub/>0.5</sub> Sn <sub/>0.5</sub> O <sub/>2</sub> Solid Solution Microspheres for Effective Photocatalytic Removal of As(III)
摘要： The development of highly efficient photocatalyst for oxidizing and further removing toxic As(III) from water environment remains a big challenge. Herein, mesoporous Ti0.5Sn0.5O2 (TSO-0.5) solid solution microspheres are synthesized by a facile solvothermal method and followed by annealing. The mesoporous TSO-0.5 microspheres are systematically characterized in terms of the crystalline phases, morphological, optical, photoelectric and photocatalytic properties using X-ray diffraction, scanning electron microscopy, N2 sorption-desorption, X-ray photoelectron spectroscopy, UV-vis diffuse reflectance spectroscopy, and electrochemical analysis. The characterizations show the TSO-0.5 are of well crystallinity, hierarchical mesoporosity, broad-light responsive capacity, large surface area, and excellent photoelectric features. Under irradiation, the mesoporous TSO-0.5 microspheres exhibit ultrahigh photocatalytic activity for methyl orange degradation (0.537 min-1?m-2, ~8 times that of TiO2) and As(III) removal (up to 98.4%). The photogenerated holes are determined to be the primary active species in the photocatalysis process of MO-degradation and As(III)-oxidation. Based the results, a possible mechanism of photo-induced charge transfer and subsequent reaction processes over the TSO-0.5 is proposed.
关键词： photocatalytic oxidation,As(III) removal,solid solution,mesoporous Ti0.5Sn0.5O2,photocatalyst
更新于2025-09-09 09:28:46
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Synthesis of Uniform Ordered Mesoporous TiO2 Microspheres with Controllable Phase Junctions for Efficient Solar Water Splitting
摘要： As a benchmark photocatalyst, commercial P25-TiO2 has been widely used for various photocatalytic applications. However, the low surface area and poorly porous structure greatly limit its performance. Herein, uniform ordered mesoporous TiO2 microspheres (denoted as Meso-TiO2-X, X represents the rutile percentage in the resulted microspheres) with controllable anatase/rutile phase junctions and radially oriented mesochannels were synthesized by a coordination-mediated self-assembly approach. The anatase/rutile ratio in the resultant microspheres can be facilely adjusted as desired (rutile percentage: 0–100) by changing the concentrations of hydrochloric acid. As a typical one, the yielded Meso-TiO2-25 microspheres have a similar anatase/rutile ratio with commercial P25. But the surface area (78.6 m2 g–1) and pore volume (0.39 cm3 g–1) of the resultant microspheres are larger than that of commercial P25. When used as the photocatalysts for H2 generation, the Meso-TiO2-25 delivers a high solar-driven H2 evolution rate under air mass 1.5 global (AM 1.5G) and visible-light (λ > 400 nm), respectively, which are significantly larger than that of commercial P25. This coordination-mediated self-assembly method paves a new way toward the design and synthesis of high performance mesoporous photocatalysts.
关键词： water splitting,mesoporous TiO2,phase junctions,self-assembly,photocatalysis
更新于2025-09-09 09:28:46
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Tungsten doped M-phase VO2 mesoporous nanocrystals with enhanced comprehensive thermochromic properties for smart windows
摘要： The phase transition temperature (~ 68 oC) of M-VO2 film can be lowered significantly by tungsten (W) doping into the crystal lattice of VO2 due to the reduction of the strength of V-V pair interaction. However, W doping was always coupled with a serious weakening of luminous transmittance and solar modulation efficiency because W dopants can increase the electron concentration of VO2 film. Herein, the simultaneous introduction of W dopants and mesopores into M-VO2 nanocrystals was employed to prepare VO2 film. Interestingly, the obtained 0.4 at% W-doped mesoporous VO2 nanocrystals based composite films exhibited enhanced comprehensive thermochromic performance with excellent solar modulation efficiency (ΔTsol = 11.4%), suitable luminous transmittance (Tlum = 61.6%) and low phase transition temperature around 43 oC, much lower than 65.3 oC of undoped VO2. It was demonstrated that the lower phase transition temperature of VO2 can be primarily attributed to abundant lattice distortion after W doping, whereas the mesoporous structure can facilitate the uniform distribution of W dopants in VO2 nanocrystals, enhance the luminous transmittance and guarantee enough VO2 nanocrystals in the composite film to keep relatively high solar modulation efficiency. Therefore, this work can provide a new way to balance the three important parameters for the thermochromic performance of VO2 film (ΔTsol, Tlum and Tc) and probably promote the application of VO2 nanocrystals in the energy efficient windows.
关键词： thermochromic performance,phase transition temperature,mesoporous structure,W-doped VO2
更新于2025-09-09 09:28:46
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Near-Room-Temperature Ethanol Gas Sensor Based on Mesoporous Ag/Zn-LaFeO <sub/>3</sub> Nanocomposite
摘要： The rational design of heterojunction between different metal oxides with mesoporous structures has attracted tremendous attention due to their special physicochemical properties and vital importance for practical applications. In this paper, mesoporous Ag/Zn–LaFeO3 nanocomposite is successfully synthesized through a facile nanocasting technique using KIT-6 as a hard template in sol–gel route and used as sensing materials to achieve an exceptionally sensitive and selective detection of trace ppm-level ethanol. The obtained composite possesses high surface area and exhibits excellent sensing response (64.2 for 100 ppm) to ethanol at near-room with relatively fast response/recovery time. When tested with the concentrations as low as 5 ppm, it also shows a remarkably high selectivity to the ethanol, but only minor responses to other interfering gases. These enhanced gas-sensing properties are attributed to the combination of mesoporous nanostructure and Ag/Zn–LaFeO3 heterogeneous composites.
关键词： mesoporous,ethanol,gas sensors,near-room temperature,Ag/Zn–LaFeO3 nanocomposite
更新于2025-09-09 09:28:46
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Mix-&-Read Determination of Mercury(II) at Trace Levels with Hybrid Mesoporous Silica Materials Incorporating Fluorescent Probes by a Simple Mix-&-Load Technique
摘要： The synthesis, characterization, and application of mesoporous materials containing boron–dipyrromethene (BODIPY) moieties that allow the sensitive and selective detection of HgII in aqueous environments by fluorescence enhancement is reported. For this purpose, BODIPY dye I containing a thia-aza crown ether receptor as the fluorescent probe for the detection of HgII in aqueous environments is encapsulated into mesoporous materials to avoid self-quenching or aggregation in water. Determination of HgII is accomplished within a few seconds with high selectivity and sensitivity, reaching a limit of detection of 12 ppt. The determination of trace amounts of HgII in natural waters and in fish extracts is demonstrated by using our sensing material. The incorporation of the material into several m-PAD strips yields a portable, cheap, quick, and easy-to-handle tool for trace HgII analysis in water.
关键词： dyes/pigments,mercury,fluorescence,mesoporous materials,test strips
更新于2025-09-09 09:28:46
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Mesoporous silica modified luminescent Gd2O3:Eu nanoparticles: physicochemical and luminescence properties
摘要： Highly colloidal Gd2O3:Eu nanoparticles (core-NPs) were synthesized by thermal decomposition via weak base at low temperature. The sol–gel chemical process was employed for silica layer surface coating to increase solubility, colloidal stability, biocompatibility, and non-toxicity at the ambient conditions. XRD results indicate the highly puri?ed, crystalline, single phase, and cubic phase Gd2O3 nanocrystals. TEM image shows that the mesoporous thick silica layer was effectively coated on the core nanocrystals, which have irregular size with nearly spherical shape and grain size about 10–30 nm. An absorption spectra and zeta potential results in aqueous media revealed that solubility, colloidal stability, and biocompatibility character were enhanced from core to core–shell structure because of silica layer surface encapsulation. The samples, demonstrated excellent photoluminescence properties (dominant emission 5D0 → 7F2 transition in the red region at 610 nm), indicated to be used in optical bio-detection, bio-labeling, etc. The photoluminescence intensity of the silica shell modi?ed core/shell NPs was suppressed relatively core-NPs; it indicates the multi-photon relaxation pathways arising from the surface coated high vibrational energy molecules of the silanol groups. The core/nSiO2/mSiO2 nanocrystals display strong emission (5D0 → 7F2) transition along with excellent solubility and biocompatibility, which may ?nd promising applications in the photonic based biomedical ?eld.
关键词： silica,Gadolinium oxide,Biocompatible,Luminescence properties,Zeta potential,Mesoporous
更新于2025-09-09 09:28:46
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Synthesis of nanopolycrystalline mesoporous diamond from periodic mesoporous carbon: Mesoporosity increases with increasing synthesis pressure
摘要： We report the catalyst-free synthesis of monolithic mesoporous nanopolycrystalline diamond from periodic mesoporous carbon at pressures between 15 and 21 GPa and a temperature of 1300 °C. We investigated the pressure-dependence of the porosity with 3-dimensional electron tomography. We have observed that surface areas increase from 56 to 90, 138 m2 g?1, and porosities increase from 10, 24, to 33% for materials produced at 15, 18, and 21 GPa, respectively. The increased porosity at higher pressure may be due to the earlier onset of the nucleation of diamond at higher pressure.
关键词： Synthesis,Diamond,Nanopolycrystalline,Electron tomography,Mesoporous
更新于2025-09-09 09:28:46
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Outstanding hydrogen evolution performance of supported Pt nanoparticles: Incorporation of preformed colloids into mesoporous carbon films
摘要： Platinum is the best catalyst known so far for the hydrogen evolution reaction (HER) in acidic environments, but it is also a scarce and expensive resource. Maximizing its performance per metal atom is essential in order to reduce costs. The deposition of small Pt nanoparticles (2–3 nm) onto electrically conductive, highly accessible and stable carbon supports leads to active catalysts. However, blocking of pores and active sites by Na?on, which acts as a binding species, reduces the catalytic activity. Moreover, inaccessible Pt located in micropores diminishes an ef?cient exploitation of the noble metal. We report a new synthesis approach to ordered mesoporous carbon (OMC) coatings with preformed Pt nanoparticles. The particles are exclusively located inside the mesopores. Furthermore, no Na?on binder is needed. As a consequence, the PtNP/OMC catalyst ?lm outperforms Pt/C catalysts reported in literature particularly at high current densities. PtNP/OMC catalyst ?lms with a geometric Pt loading of 1.6 mgPt/cm2 achieve a current density of (cid:1)100 mA/cm2 at an overpotential of ca. (cid:1)70 mV.
关键词： Ordered mesoporous carbon,Noble metal colloids,Electrocatalysis,Mesoporous ?lms,Hydrogen evolution reaction
更新于2025-09-04 15:30:14