Journal of Materials Chemistry C
·
2020
·Vol. 8
·期 30
·10333-10341
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IF 7.059
Jiaqi Sheng,Xiaofang Liu,Chengzhi Niu,Yufeng Sun,Yao Chen,Hengyang Wang,Bin Zhang,Guoyu Wang,Xiaoyuan Zhou,Guang Han
Bottom-up solution synthesis has been considered as a facile and energy-efficient approach for SnSe thermoelectric materials. Herein, we report a microwave-assisted hydrothermal method for the fast and controllable synthesis of SnSe with optimised thermoelectric properties. The NaOH concentration in solution precursors was demonstrated as a key factor influencing the phase composition, diameter, and morphology of the hydrothermal products as well as the thermoelectric properties of the corresponding sintered pellets. It is found that a NaOH : SnCl2 molar ratio of 30 leads to the formation of phase-pure SnSe microrods, and the pellet constructed from these rods obtains a maximum ZT of 1.08 and 0.78 at 773 K in parallel and perpendicular alignments to the pressing direction, respectively. These ZT values are significantly higher than the ZT value achieved by the pellet that was sintered from the hydrothermal powders prepared without NaOH and comprised the mixed phases of SnSe, SnO2, and SnSe2. This enhancement is primarily due to the improved power factor together with the lower lattice thermal conductivity owing to the significantly reduced fraction of SnO2 in the pellet. This study not only provides a microwave-assisted solution strategy for the fast, efficient, and controllable synthesis of SnSe materials, but also identifies the key synthesis parameters for securing better thermoelectric performance.
研究领域:
材料科学
·
能源材料
·
热电材料
✓ 已验证
DOI
高影响因子
IONICS
·
2018
·Vol. 25
·期 5
·2211-2219
·
IF 2.347
Chen Si,Gao Lin,Zhang Lulu,Yang Xuelin
Four types of mesoporous Na 2 Ti 3 O 7 (NTO) microspheres have been successfully prepared utilizing different concentrations of NaOH treatment. The specific surface areas and pore size distributions of NTO can be well controlled by means of adjusting the amount of NaOH additives. In the meanwhile, the corresponding electrochemical performance has been detected and analyzed. It is concluded that the 3 M-NTO sample prepared with 3 M NaOH solution exhibits the best electrochemical performance. We consider that the less or excess amount of NaOH might not be beneficial to building the most optimal model for efficient Na + ion storage. The addition of NaOH less than 2 M leads to the relatively low surface areas and pore volume, bringing about limited contact areas between active materials and Na + ions as well as unsatisfied specific capacity. On the other hand, the excess augment of NaOH is reversely detrimental to the improvement of electrochemical performance probably owing to the fragile construction of NTO caused by the abundant mesopore distribution.
研究领域:
材料科学
·
能源存储
✓ 已验证
产品关联
DOI
高影响因子
RSC Advances
·
2021
·Vol. 11
·期 60
·37760-37766
·
IF 3.361
Xiaodong Yang,Jia Li,Jianhua Yao,Tianrui Ren,Bo Zhang
The precise control architectures of Cu2O crystals are very crucial, which have a significant influence on their various performances. Herein, Cu2O crystals with diverse architectures were achieved via finely adjusting the concentration of NaOH. The intriguing results showed that the addition of specific amounts of OH− to the solution was crucial to tailor the morphology and size of the resulting microcrystals. We observed the evolution of the shapes of the Cu2O microcrystals, which change from a rhombic dodecahedron to spherical, octahedral-like and then to hexapod upon the increase in the NaOH concentration. Adjusting the volume of NaOH added provides a means to vary the particle size. Furthermore, density functional theory (DFT) may reveal that OH− ions serve as an efficient coordination agent selectively adsorbing onto different crystal faces of Cu2O crystals modifying the crystal energies, inducing the structure anisotropy on crystal growth. This work reveals that an effective and facile strategy has been developed for morphology-control of Cu2O crystals.
研究领域:
材料科学
·
化学
✓ 已验证
产品关联
DOI
PubMed
高影响因子
CARBOHYDRATE POLYMERS
·
2025
·
IF 12.5
Jinping Peng,Rongwei Fu,Yihui Huang,Jinqing Lu,Xiaofeng Xie,Zhenkun Xue,Mingjie Chen,Xingrou Wu,Hangbo Yue,Haiyan Mai
Alkaline aqueous solutions facilitate the rapid extraction of high-performance cellulose nanofiber (CNF) at 15 °C. However, the role and mechanism of NaOH in this process remain unclear. This study investigated the dissolution process of cellulose by controlling the NaOH concentration (1–7 wt%) at 15 °C and explored the effect and underlying mechanism of the NaOH concentration on cellulose dissolution in alkaline solvents. The results showed that the addition of NaOH strengthened the hydrogen bonding network of the solvent, whereas the addition of urea and thiourea promoted the dissolution of cellulose. The higher the concentration of NaOH is, the smaller the volume of hydrate molecules formed; smaller molecules more readily enter the cellulose molecules and form new hydrogen bonds with cellulose molecular chains, thereby destroying the original hydrogen bonds between cellulose molecules and their crystal structure. During dissolution, cellulose decomposes into microfibrils, and nanosized cellulose separates; moreover, the diameter and length of the CNF decrease with increasing NaOH concentration. When the concentration of NaOH reaches 7 %, the cellulose is completely broken down into CNF, and the yield is >60 %. As dissolution progresses, the crystallinity of cellulose first increases and then decreases (75.95 %–81.00 %–77.02 %), but its crystal size remains unchanged.
研究领域:
材料科学
·
化学工程
✓ 已验证
产品关联
DOI
PubMed
高影响因子
RARE METAL MATERIALS AND ENGINEERING
·
2014
·
IF 0.153
Zhiqiang Zhou,Guo Li,Peiyun Jia
GdVO 4 :Eu 3+ nanophosphors were prepared via molten salt synthesis. Equal moles of NaNO 3 and KNO 3 were used as reaction medium, rare earth nitrates and NH 4 VO 3 as precursors, and NaOH as alkalizer. X-ray diffraction (XRD), Fourier transform infrared (FT-IR), transmission electron microscopy (TEM), photoluminescence (PL) spectrum and lifetime were used to characterize the nanophosphors. XRD demonstrates that NaOH concentration and the sintering temperature play important roles in the crystallinity and the phase purity of the products. The optimum NaOH concentration and sintering temperature are 2:40 and 400 °C, respectively. TEM micrographs show that the GdVO 4 :Eu 3+ nanocrystals exhibit a cubic morphology and have a mean size of about 20 nm, which is in good agreement with that calculated by Scherrer's formula. Both the cell parameters and the volume of GdVO 4 :Eu 3+ nanocrystals decrease due to the existence of big quantity of dangling bonds on the particle surface. Upon excitation at 315 nm, the GdVO 4 :Eu 3+ nanocrystals show the strong characteristic emission of Eu 3+ , which indicates the efficient energy transfer from VO 4 3- groups to Eu 3+ . The best doping concentration of Eu 3+ in GdVO 4 is determined to be 5 mol%.
研究领域:
材料科学
·
纳米技术
·
光学
✓ 已验证
DOI
高影响因子
危险品化学品经营许可证（带存储）