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Controlled Fabrication of K2Ti8O17 Nanowires for Highly Efficient and Ultrafast Adsorption towards Methylene Blue
摘要： Advanced adsorbents need high adsorption rate and superior adsorption capability to clean up the organic methylene blue (MB) from wastewater. We prepared K2Ti8O17 nanowires grown along [0 1 0] direction with a one-step hydrothermal method. The K2Ti8O17 nanowires with tens of nanometers in diameter and tens of micrometers in length were achieved with smooth surfaces and twisted wire-like morphology. The K2Ti8O17 nanowires exhibit high uptake capacity of ～208.8 mg·g?1 in the MB removal under equilibrium pH = 7. The adsorption equilibriums of MB onto K2Ti8O17 adsorbent is achieved with 97% removal rate MB within only ~21 min, which is the shortest adsorption time among the recent reported inorganic adsorbents towards MB. The adsorption process has a good agreement with the well-known pseudo-second-order kinetic model (k2 = 0.2) and the Langmuir isotherm model. The FTIR measurements suggest that the adsorption can be assigned to the hydrogen bonding and electrostatic attraction between MB and K2Ti8O17. This ultrafast removal ability owns to the larger (0 2 0) interplanar spacing and zigzag surface structure of the nanowires, which provide abundant active adsorption sites. Thermodynamic parameters reflect the spontaneous, exothermic and feasible uptake of MB. Besides, K2Ti8O17 nanowires enjoy high adsorptive ability for chromium (VI) ions and photocatalytic removal towards NO. This work highlights the great significance of K2Ti8O17 nanowires as a low cast promising material used for adsorptive elimanation of organic contaminations in fast water purification on a large scale.
关键词： Hydrothermal synthesis,Tunnel-layered structure,Adsorption capability,K2Ti8O17 nanowires,Thermodynamics,Kinetics,Isotherms
更新于2025-09-16 10:30:52
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Silicate-germanates with the doubled mica-like layers [Pb(Si,Ge)O4]2-∞∞ in centrosymmetric Rb2Pb2[(Ge0.33Si0.67)2O7] and isolated in acentric, optically nonlinear Li6Pb2[(Ge0.4Si0.6)O4]2(OH)2
摘要： Silicate-germanates, Rb2Pb2[(Si0.67Ge0.33)2O7], P m1, and Li6Pb2[(Ge0.4Si0.6)O4]2(OH)2, P63mc, were synthesized in the multi-component hydrothermal systems. According to single crystal XR data, both structures contain identical mica-like layers [Pb(Ge,Si)O4]2- ∞∞, double or single, comprised of [(Si,Ge)O4]4--tetrahedra and umbrella-like groups [PbO3]4-: the latter play a unique role of (Si,Ge)-tetrahedra being of the same charge, dimension and the Pb-lone-pair as the forth apex. Predicted earlier polar ortho-silicate structure appears with small Li atom, while the centrosymmetric diortho-silicate structure type A2Pb2[B2O7] is stable with large A = K, Rb, Cs. Layers with {Li3O7}11- atomic clusters separate single tetrahedral layers. Under Nd:YAG laser illumination the powder of acentric Li,Pb-silicate-germanate yields intensive light of second harmonic. The maximum second harmonic intensity 10 times more in comparison with quartz standard is achieved in the powder with a grain size of about 20 μm. The space-averaged second-order nonlinear coefficient <d> = 1.1 pm/V. The comparably high optical nonlinearity is connected with the one-side directed umbrella-like polar units [PbO3]4- in polar structure of the Li,Pb-silicate-germanate.
关键词： materials design,structure,hydrothermal synthesis,lead-silicate-germanate,structure-properties relations,optical nonlinearity
更新于2025-09-16 10:30:52
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Controlled Hydrothermal Synthesis of K<sub>2</sub>Ti<sub>6</sub>O<sub>13</sub> Nanowires and their Photo-Electronic Response
摘要： A hydrothermal method using tetrabutyl titanate and KOH as reactants for synthesis of K2Ti6O13 nanowires was developed, obtaining nanowires with a uniform diameter around 10nm. It is shown that the hydrothermal temperature and the KOH concentration have little influence in tuning the growth of K2Ti6O13 nanowires. By changing the time for hydrothermal reaction, the length of K2Ti6O13 nanowires can be controlled from several dozen of nanometers to several hundreds of nanometers. The as-prepared K2Ti6O13 nanowires exhibit a wide and strong absorption band in the ultraviolet range (around 200~300 nm), and stable photocurrent of 0.5μA/cm2, which might suggest potential applications in solar cell and water splitting.
关键词： photo-electronic response,hydrothermal synthesis,K2Ti6O13 nanowires
更新于2025-09-16 10:30:52
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Photoluminescence and Photodetecting Properties of the Hydrothermally Synthesized Nitrogen-Doped Carbon Quantum Dots
摘要： Carbon quantum dots (CQDs) have attracted more and more attention as the representative of a new generation of photoluminescence (PL) and photodetecting materials due to their unique optoelectrical properties. However, the formation mechanism of the CQDs as well as the origin of PL from the CQDs are still open questions to be issued. Here, we report our recent progress on the synthesis of the nitrogen-doped carbon quantum dots (N-CQDs) with a high photoluminescence quantum yield (PLQY) of 97.4% by adjusting the hydrothermal synthesis parameters with the citric acid (CA) and ethylenediamine (EDA) as the precursors. The detailed structure and properties indicate that N-CQDs is synthesized by dehydration, condensation, and carbonization, and the PL is attributed to the synergistic effect of the carbogenic core and the surface/molecule state. With above progress, an all-carbon-based ultra-violet (UV) photodetector is fabricated based on the N-CQDs/graphene hybrid composites, which exhibits significant negative photoconductivity phenomenon. A maximal negative responsivity up to 2.5×104 AW-1 at UV region has been observed, which was attributed to the two competing mechanisms. One is the oxygen adsorption and photo-desorption induced negative photoresponse, while the other is the surface defects in N-CQDs related positive photoconducting. Our work reveals the mechanisms driven force behind positive and the negative photoconducance phenomenon of photodetectors based on CQDs, which not only contributes to the further understanding of the fluorescent and photoresponse mechanisms of CQDs, and promotes the application potential of CQDs in the field of photodetection and nano-optoelectronic sensors.
关键词： Photodetecting,Nitrogen-doped,Hydrothermal synthesis,Photoluminescence,Carbon quantum dots
更新于2025-09-16 10:30:52
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Nitrogen plasma treatment of ZnO and TiO2 nanowire arrays for polymer photovoltaic applications
摘要： This work reports on a simple, yet unique approach to improving the opto-electronic properties of vertically-aligned arrays of rutile TiO2 and Wurzite ZnO nanowires by means of controlled nitrogen doping during exposure to highly kinetic radio-frequency generated N2 plasma radicals. Morphologically, the plasma treatment causes a distortion of the vertical alignment of the nanowires due to a dissociation of the weak Van der Waals force clustering the nanowires. Optical spectroscopy show that plasma treatment increases the light transmission of TiO2 arrays from 48% to 90%, with the ZnO arrays exhibiting an increase from 70% to 90% in the visible to UV range. The as-synthesized TiO2 array has an indirect band gap of 3.13 eV, which reduces to 3.03 eV after N2 treatment, with the ZnO equivalent decreasing from 3.20 to 3.17 eV post plasma exposure. A study of the 3d transition metal near edge fine structure of both Ti and Zn show that the N2 plasma treatment of the nanowires results in nitrogen doping of both TiO2 and ZnO lattices; this is confirmed by scanning transmission electron microscopy coupled with energy dispersive spectroscopy x-ray maps collected of single nanowires, which show a clear distribution of nitrogen throughout the metal-oxide. Application of these structures in P3HT:PCBM polymer blends shows progressive improvement in the photoluminescence quenching of the photoactive layer when incorporating both undoped and nitrogen-doped nanowires.
关键词： Electron energy loss spectroscopy,RF plasma nitrogen doping,One-dimensional nanowire arrays,Hydrothermal synthesis
更新于2025-09-16 10:30:52
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Controlled hydrothermal synthesis of different sizes of BaTiO<sub>3</sub> nano-particles for microwave absorption
摘要： Different sizes of barium titanate (BaTiO3) nano-particles were synthesized from precursor H2Ti3O7 nanotubes through facile hydrothermal synthesis by using EtOH/H2O as mixing solvent. Field-emission scanning electron microscopy (FESEM) was mainly used to investigate the effects of solution alkalinity, polarity, and hydrothermal temperature on the size and morphology evolution of BaTiO3 nanoparticles. The results indicate that the presence of strong alkalinity improved the size evenness of BaTiO3 nanoparticles possibly because of the re-dissolution and re-precipitation of TiO3 2- ions. As for the reason, the addition of EtOH could lower the polarity of hydrothermal medium and make the medium reach the supersaturation more easily, thus limiting the size growth of BaTiO3 particles. In addition, the presence of EtOH led to easier formation of BaTiO3 nanoparticles even at mild hydrothermal temperature, but the particle size was limited even though the temperature was much increased. This is possibly due to lowered interfacial activity in the presence of EtOH. By adjusting solution alkalinity, EtOH/H2O volume ratios, and hydrothermal temperature, BaTiO3 nanoparticles with the average sizes of approximately 21, 53, 104, 284, and 512 nm, were obtained, and more different and controlled nano-sizes can be expected by further hydrothermal adjustment. In the end, microwave absorption evaluation indicated that the decreased size of the BaTiO3 particles enhanced the reflection loss. One possible reason is that the decreased nano-size led to the increased specific surface area of the BaTiO3 nanoparticles.
关键词： Hydrothermal synthesis,Barium titanate,Polarity,Temperature,Microwave absorption,Adjustable nano-size
更新于2025-09-16 10:30:52
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Photovoltaic Properties of an rGO/Pt Counter Electrode with AZO Photoanode for Dye-sensitized Solar Cells under Low Light Intensity
摘要： This study used reduced graphene oxide (rGO) applied to a platinum (Pt) counter electrode to improve light conversion efficiency. The study also used an Al-doped Zinc Oxide (AZO) nanosheet / TiO2 photoanode for the dye-sensitized solar cell (DSSC). Photovoltaic characteristics, electrochemical impedance spectroscopy (EIS), field-emission scanning electron microscopy (FE-SEM) and Raman spectroscopy were used to analyze DSSC. The different light intensities and photovoltaic characteristics were analyzed to determine optimal light intensity conditions. The unmodified Pt counter electrode was compared with the rGO/Pt counter electrode, photovoltaic conversion efficiency (η) increased from 3.60% to 4.04% due to the rGO modification as it possesses a higher specific surface area. Its low cost also makes it suitable for mass production. In addition, an AZO nanosheet / TiO2 photoanode was fabricated to form a double-layer structure in which photovoltaic conversion efficiency was 4.47 %. Finally, a DSSC with an AZO / TiO2 photoanode and rGO/Pt counter electrode was fabricated and had an photovoltaic conversion efficiency of 5.05 %. This study also analyzed the photovoltaic parameters of DSSC under different intensities, which shows the optimal photovoltaic conversion efficiency of 5.54% under 30mW / cm2.
关键词： photovoltaic conversion efficiency,low light intensity,Al-doped Zinc Oxide (AZO),hydrothermal synthesis,Dye-sensitized solar cell (DSSC),reduced graphene oxide (rGO)
更新于2025-09-12 10:27:22
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Photocatalyst properties depend on the mix
摘要： Photocatalysts use light to power chemical reactions in a whole host of applications from fuel cells to water remediation. There are many ways to improve the performance of titania (TiO2) photocatalysts from using catalyst support materials, which increase photosensitization rates, and help break down organic pollutants, to doping or co-doping with other atoms to expand the absorption range. Since using metal atoms such as dopants is problematic for water treatment if they leach into the environment, non-metallic dopants like nitrogen (N) are considered safer. Researchers from the University of South Africa have used these two strategies in conjunction to produce N-doped TiO2 photocatalysts on a carbon nanotube (CNT) support and systematically compared the effects of using different synthesis routes. Edward N. Nxumalo and his team find that photocatalysts with distinctly different properties and performance are produced depending on whether a hydrothermal or solgel synthetic route is used.
关键词： Carbon nanotubes,Hydrothermal synthesis,Solgel synthesis,Nitrogen doping,Photocatalysts,TiO2
更新于2025-09-11 14:15:04
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Supermagnetic Fe <sub/>3</sub> O <sub/>4</sub> -PEG nanoparticles combined with NIR laser and alternating magnetic field as potent anti-cancer agent against human ovarian cancer cells
摘要： In the present study the magnetite nanoparticles Fe3O4 capped with polyethylene glycol PEG were prepared by hydrothermal method. Syntheses bare Fe3O4, and Fe3O4-PEG were confirmed by various techniques including X-ray powder diffraction (XRD), Transmission electron microscope (TEM), Dynamic light scattering (DLS), Scanning electron microscope (SEM), and Vibrating sample magnetometer (VSM) techniques were used to examine the magnetic properties of the Fe3O4 MNPs. The bare Fe3O4 had an average size that ranged between 12-31nm while Fe3O4- PEG had a size range of 5-15 nm. The effect of bare Fe3O4 and Fe3O4-PEG on SKOV-3 cell proliferation was measured by MTT assay. The ability of bare Fe3O4 and Fe3O4-PEG in induction of apoptosis was tested using Acridine orange/ Ethedium bromide stain. Cytotoxicity effects of bare Fe3O4 and Fe3O4-PEG against SKOV-3 cells in the presence and absence of laser photo-thermal therapy and alternating magnetic field (AMF) was also assessed. The results showed that both bare Fe3O4 and Fe3O4-PEG caused inhibition of SKOV-3 cell proliferation, resulting in their programmed death. Cytotoxic activity against SKOV-3 cells increased with NIR laser irradiation, while highly increased cytotoxic activities were observed after exposure to induction heating with AMF. In addition, the toxicity of investigated nanoparticles in liver function enzymes and histological alterations for spleen, and the lungs were addressed. The findings indicated that these nanoparticles were biocompatible with liver function enzymes and no significant alterations were recorded in the spleen, and the lungs. Taken together the present data suggest that bare Fe3O4 and Fe3O4-PEG with NIR laser and AMF could be promising for photothermal therapy protocol for cancer cells.
关键词： NIR laser,Hydrothermal synthesis,SKOV-3 cells,anticancer activity,Fe3O4-PEG,AMF
更新于2025-09-11 14:15:04
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Hydrothermal Synthesis and Upconversion Properties of About 19?nm Sc2O3: Er3+, Yb3+ Nanoparticles with Detailed Investigation of the Energy Transfer Mechanism
摘要： The Sc2O3: Er3+, Yb3+ nanoparticles (NPs) with the size of about 19 nm were synthesized by a simple oleic acid-mediated hydrothermal (HT) process. X-ray diffraction (XRD), transmission electron microscopy (TEM), upconversion luminescence (UCL) spectra, and decay curves were used to characterize the resulting samples. The Sc2O3: Er3+, Yb3+ NPs made by HT method exhibit the stronger UCL, of which the red UCL are enhanced by a factor of 4, in comparison with those samples prepared by solvothermal (ST) method at the same optimized lanthanide ion concentrations. The UCL enhancement can be attributed to the reduced surface groups and longer lifetimes. Under 980 nm wavelength excitation, the decay curves of Er3+: (2H11/2, 4S3/2) → 4I15/2 and 4F9/2 → 4I15/2 emissions for Sc2O3: Er3+, Yb3+ NPs samples are both close to each other, resulting from the cross relaxation energy transfer from Er3+ to Yb3+, followed by an energy back transfer within the same Er3+-Yb3+ pair. Also, under the relatively low-power density, the slopes of the linear plots of log(I) vs. log(P) for red and green emissions are 2.5 and 2.1, implying the existence of three-photon processes. Our results indicate that Sc2O3: Er3+, Yb3+ NPs is an excellent material for achieving intense UCL with small size in the biological fields.
关键词： Hydrothermal synthesis,Upconversion,Sc2O3,Energy transfer,Er3+/Yb3+
更新于2025-09-11 14:15:04