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Two new olefin-Cu(I) coordination polymers based on 2,5-dimethyl piperazine: Synthesis, crystal structure and fluorescent property
摘要： Two new olefin-Cu(I) coordination polymers, i.e. [Cu6(DMBVBP)Cl8]n (1) and [Cu6(DMBVBP)Br8]n (2) (DMBVBP ? 2,5-dimethyl-1,4-bis(4-vinylbenzyl) piperazine), were synthesized through the solvothermal reactions of CuCl, CuBr and 2,5-dimethyl piperazine and further characterized by elemental analysis, infrared spectroscopy, as well as powder and single crystal X-ray diffraction analyses. The title complexes crystallized in the monoclinic P-1 space group, both featuring a one-dimensional chain. Their fluorescent properties were also investigated.
关键词： fluorescence,Olefin-Cu(I) coordination polymer,hydrothermal synthesis
更新于2025-09-19 17:15:36
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Amplified spontaneous emission (ASE) and laser effects in ?2-LiYF4: Ce, Tb micro- and nanocrystals
摘要： β-NaYF4 crystals family are interesting materials and have potential for various applications. Here we present our research regarding amplified spontaneous emission (ASE) and laser effects of three materials: LiY0.7 F4: (Ce0.2 Tb0.1), NaY0.5 F4: (Ce0.4 Tb0.1) and LiLuY0.7 F4: (Ce0.2 Tb0.1), prepared by hydrothermal synthesis method. The luminescent active ion is Tb3+. β- LiY0.7 F4: (Ce0.2 Tb0.1) crystals with a hexagonal plate shape have ASE threshold at 400 mW/cm2, excitation with λex = 365 nm and a laser threshold at 490 J for a doped PMMA rod with a length of 25 mm. Laser line was observed at 542 nm.
关键词： β-LiYF4: Ce, Tb micro- and nanocrystals,Laser effect,Amplified spontaneous emission (ASE),Hydrothermal growth
更新于2025-09-19 17:13:59
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Optical fiber coated Zinc Oxide (ZnO) nanorods decorated with Palladium (Pd) for hydrogen sensing
摘要： A novel hydrogen (H2) sensor was developed using acid-etched optical fiber coated with zinc oxide (ZnO) nanorods. The sensing performance was done by comparing the acid-etched fiber coated with ZnO nanorods with and without decorated Palladium (Pd). The conventional optical single-mode fiber (SMF) with a diameter of 125 μm has been modified as a transducing platform by etching it to 11 μm diameter using hydrofluoric acid (HF) to enhance the evanescent field of the light propagates in the fiber core. The etched fiber was coated with ZnO nanorods via hydrothermal process by using seeding and growth solution method. The sensing layer was characterized through Scanning Electron Microscopy (SEM), Energy Dispersive X-Ray (EDX) and X-Ray Diffraction (XRD) to verify the properties of ZnO. Catalyst Palladium (Pd) was sputtered onto the ZnO nanorods to improve H2 detection. The developed sensor operating temperature was found to be 150 °C that produces 6.36 dBm increase in response towards the 1% concentration of H2 in synthetic air. It was then tested with different concentration of H2. The sensor decorated with Pd has better performance in sensing compared to non-decorated Pd based on the output power versus time. The sensor best response and recovery times is 6 and 5 min respectively, for acid-etched optical fiber coated with ZnO nanorods decorated with Pd for 0.75% of H2 concentrations at 150 °C. The results indicate the optical fiber sensor might improve the performance towards H2 as oppose to the conventional electrical sensor.
关键词： Zinc oxide nanorods,Etching optical fiber,Hydrothermal method,Light-intensity response,Hydrogen sensor,Fiber optic sensor
更新于2025-09-19 17:13:59
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Facile and highly effective synthesis of nitrogen-doped graphene quantum dots as a fluorescent sensing probe for Cu2+ detection
摘要： Nitrogen-doped graphene quantum dots (N-GQDs) with high blue fluorescence efficiency were synthesized by the hydrothermal method from p-Phenylenediamine and p-Coumaric acid. The N-GQDs possess several superiorities, most significantly in excellent solubility and superior photostability. Besides, the as-prepared N-GQDs exhibit a uniform size distribution with a diameter of about 3.8±0.5 nm. After dispersing the N-GQDs in water, the formed aqueous solution still presents a stable and homogeneous phase even after 2 months at room temperature. The N-GQD dispersion was further utilized as sensing probes for the selective detection of copper ions (Cu2+), which is realized by the photoluminescence (PL) quenching of N-GQDs after adding Cu2+. The detection limit for Cu2+ was found to be 57 nM L-1, with superior selectivity in the presence of other commonly interfering metal ions. The presented results in this study provide a facile and high-efficiency method for synthesizing N-GQDs, with ultra-high detectivity and selectivity for Cu2+ detection, offering numerous opportunities for the development of biosensing, bioimaging, environment monitoring, and others.
关键词： Nitrogen-doped graphene quantum dots,Hydrothermal method,Photoluminescence quenching,Cu2+ detection
更新于2025-09-19 17:13:59
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The role of GQDs additive in TiO2 nanorods as an electron transfer layer on performance improvement of the perovskite solar cells
摘要： The electron transport layer (ETL) plays an important role in improving the performance of the perovskite solar cells (PSCs). The main focus is on different types of TiO2 structures as an efficient ETL. In the present work, TiO2 nanorods (NRs) are prepared by a simple one-step hydrothermal method and employ as an ETL in PSCs. The power conversion efficiency (PCE) of the TiO2 NRs based PSCs is improved about 217% compared with the mesoporous (mp) TiO2 based cells. In order to further enhance PCE of the PSCs, a new approach is adopted to synthesize the graphene quantum dots- TiO2 NRs (GQDs- TiO2 NRs) by hydrothermal method. The PCE of PSCs based on GQDs- TiO2 NRs show improvement of 1.34 times compared to the TiO2 NRs. The GQDs- TiO2 NRs is capable of being a promising alternative to be employed as an efficient electron transport materials for photovoltaic devices.
关键词： TiO2 nanorods,Perovskite solar cells,Hydrothermal synthesis,Graphene quantum dots
更新于2025-09-19 17:13:59
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Hydrothermally-Grown TiO2 Thin Film-Based Metal–Semiconductor–Metal UV Photodetector
摘要： A metal–semiconductor–metal (MSM) ultraviolet photodetector has been fabricated by using hydrothermally-grown TiO2 thin films. Ag paint was used as a contact electrode which showed the good ohmic contact between the metal–semiconductor junctions. The effect of deposition time on the structural, morphological and photodetector properties have been studied. The prepared TiO2 thin films are polycrystalline and show a rutile crystal structure with the preferred orientation along the (110) plane. The MSM UV photodetector was illuminated under a UV lamp with an intensity of 1.8 lW/cm2 and at 5-V bias. The photocurrent of the device increased linearly with the applied voltage. The maximum photocurrent of 3.96 lA was obtained for the film deposited at 5 h and maximum spectral photoresponsivity was 13.29 A/W. The device showed a fast optical switching behavior. The high responsivity and fast photoresponse shows that fabricated TiO2 detectors are good candidates for ultraviolet photodetectors.
关键词： MSM UV photodetector,Titanium dioxide,photoresponsivity,hydrothermal method
更新于2025-09-19 17:13:59
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Controlled growth of SrxBa1a??xNb2O6??hoppera?? and cubea??shaped nanostructures by hydrothermal synthesis
摘要： Controlling the shape and size of nanostructured materials has been a topic of interest in the field of material science for decades. In this work, the ferroelectric material SrxBa1-xNb2O6 (x = 0.32–0.82, SBN) was prepared by hydrothermal synthesis, and the morphology is controllably changed from cube-shaped to hollow-ended structures based on a fundamental understanding of the precursor chemistry. Synchrotron X-ray total scattering and PDF analysis was used to reveal the structure of the Nb-acid precursor, showing Lindqvist-like motifs. The changing growth mechanism, from layer-by-layer growth forming cubes to hopper-growth giving hollow-ended structures, is attributed to differences in supersaturation. Transmission electron microscopy revealed an inhomogeneous composition along the length of the hollow-ended particles, which is explained by preferential formation of the high entropy composition, SBN33, at the initial stages of particle nucleation and growth.
关键词： SrxBa1-xNb2O6,hydrothermal synthesis,SBN,hopper crystal,niobic acid
更新于2025-09-19 17:13:59
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Phase- and shape-controlled synthesis of VO2 by a hydrothermal-calcination method
摘要： VO2(M) structures with various shapes were synthesized by vacuum annealed VO2 metastable phase, and this metastable phase (VO2(B/D)) were formed by hydrothermal method used H2C2O4 and V2O5 powders as starting reactants. The phase structure, morphology, surface composition and phase transition characteristics of VO2 were characterized by XRD, SEM, XPS and DSC. Obtained results show that the VO2’s metastable phase structure and morphology strongly depended on the n-butanol/water ratio, molar ratio of V2O5 and H2C2O4 and molar concentration of V2O5, which leads a different synthesis pathway. The influence mechanism has also been studied. Low n-butanol/water ratio (2:45) and low molar ratio (1:1, 1:2) favor the formation of VO2(B) nanosheets/nanorods while high n-butanol/water ratio (45:2) and high molar concentration (0.22 mol/L) favor the formation of VO2(D) micro/nanospheres. Ultimately, the VO2(M) nanoparticles can be obtained at a relatively low vacuum annealing temperature of 300°C, and with a lowest TC was as low as 55.43°C. In addition, the effect of vacuum annealing temperature and morphology on the phase transition characteristic of VO2(M) has also been studied.
关键词： VO2,Various shapes and phase structures,Hydrothermal,Phase transition characteristic,Vacuum annealing
更新于2025-09-19 17:13:59
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Glucose-derived porous carbon as a highly efficient and low-cost counter electrode for quantum dot-sensitized solar cells
摘要： Biomass-derived porous carbon is widely used in supercapacitors, carbon dioxide capture and lithium–sulfur batteries owing to its advantages such as wide sources, low cost and good stability. However, it is rarely used in quantum dot-sensitized solar cells (QDSCs). Here, glucose-derived porous carbon was obtained by hydrothermal carbonization followed with high-temperature KOH activation, and employed as an efficient counter electrode (CE) for QDSCs. The CV, EIS and Tafel-polarization analysis showed that porous carbon exhibits excellent catalytic activity for reduction of Sn2?. The CE based on porous carbon activated at 900 °C (C900) presents best performance with interface charge transfer resistance (Rct) of 2.4 Ω cm2 due to the synergy between high graphitization degree and large specific surface area. The power conversion efficiency (PCE) of the QDSCs assembled with a CdS/CdSe sensitized TiO2 photoanode and the C900 CE is up to 5.61% under one sun illumination. The excellent catalytic activity of C900 is attributed to its large specific surface area and porous structure and high degree graphitization. This suggests that glucose-derived porous carbon can become a potential low-cost and efficient CE material for QDSCs.
关键词： biomass-derived porous carbon,KOH activation,quantum dot-sensitized solar cells,hydrothermal carbonization,counter electrode,glucose
更新于2025-09-19 17:13:59
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Optical properties of hydrothermally synthesised and thermally annealed ZnO/ZnO <sub/>2</sub> composites
摘要： ZnO/ZnO2 composites grown by hydrothermal synthesis at low temperature (180 °C) and thermally annealed at 300 °C were fully analysed by morphological, structural and optical techniques. X-ray diffraction patterns (XRD) and Raman spectroscopy clearly evidences the presence of both crystalline phases in the ZnO/ZnO2 sample. The differential scanning calorimetry analysis and thermogravimetric profiles indicate an exothermic event with a peak temperature ca. 225 °C, which is accompanied by a 8.5 % weight loss, being attributed to the crystallization of ZnO from ZnO2. Upon a thermal annealing treatment at 300 °C in the ZnO2 phase was completely converted into ZnO as measured by XRD and Raman spectroscopy. Photoluminescence investigations reveal that the emission is dominated by a broad band recombination in both samples, which are due to the overlapping of different emitting centres, and that the peak position of the PL emission is dependent on the excitation density. The ZnO/ZnO2 sample exhibits a widening of the bandgap when compared to the one only containing ZnO, likely related with the presence of the additional ZnO2 phase and suggesting a bandgap energy of 3.42 eV for this compound. Surface analysis revealed that sample exhibits a surface area of 90 m2/g, which decreases to 30 m2/g after the thermal annealing and the full conversion into ZnO. This difference in the surface area showed a particular relevance in the stability of the measured optical properties. Particularly, the intensity of the photoluminescence signal was seen to be higher in the ZnO/ZnO2 sample and strongly dependent on the measurement atmosphere, highlighting their potential to be employed in the fabrication of optical-based sensing systems for environmental applications, namely in gas sensors.
关键词： photoluminescence,gas sensors,ZnO/ZnO2 composites,hydrothermal synthesis,optical properties
更新于2025-09-19 17:13:59