CHEMOSPHERE
·
2022
·
IF 8.943
Chao Ren,Hongtao Wang,Junfeng Ji,Wei Li
Calcination is an effective way to improve the F − adsorption capacity of layered double hydroxide (LDH) materials, however, a molecular scale understanding of the enhanced defluoridation capability of calcined LDHs (CLDH) is lacking. This study investigated the mechanisms of F − adsorption by CLDH using 19 F solid-state NMR, X-ray photoelectron spectroscopy (XPS), and high-resolution TEM . Under calcination process, LDH underwent three periods: surface dehydration below 200 °C, structural dehydroxylation at 200–400 °C, and release of interlayer carbonate groups above 400 °C. Additionally, XPS and XRD characterization showed that CLDH could not recover to the original structural symmetry even after rehydration and reconstitution. The F − affinity was greatly enhanced for the calcined LDH, especially at high pH. At pH 10, the adsorption capacity could reach 22.0 mg F − /g for CLDH (500 °C calcined), about 6 times larger than that of LDH. The XRD analyses revealed that the F-adsorbed CLDH had a poorer crystalline degree as the calcination temperature increased, consistent with the TEM observation of abundant defects and Mg/Al oxides on the CLDH sheets. 19 F solid-state NMR spectra of the CLDH after F − adsorption showed that the formation of surface Al–F is the predominant F − adsorption mode at pH 7, whereas the Mg–F local coordination mode is the pronounced F − adsorption mechanism under alkaline conditions (pH 10). The present study provided a comprehensive understanding of CLDH in F − adsorption and suggested that calcination is a promising treatment for promoting the efficacy of polluted anion scavenging.
研究领域:
环境科学
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材料科学
✓ 已验证
产品关联
DOI
PubMed
高影响因子
MATERIALS CHEMISTRY AND PHYSICS
·
2022
·
IF 4.778
N.R. Khalid,Hamid Ishtiaq,Faisal Ali,M.B. Tahir,Sumaira Naeem,A. Ul-Hamid,M. Ikram,T. Iqbal,M. Rizwan Kamal,Hussein Alrobei,Meshal Alzaid,A. Dahshan
The fast pace of industrial growth during the current decade has seen a large family of dyes employed copiously in the production of various products such as paper and ink. These dyes pollute earth's ecosystems. Researchers look at various ways to degrade these dyes including the use of suitable nanomaterials . ZnO is an important semiconductor material that can be employed for this purpose. In this research work, we optimized the photocatalytic capability of ZnO by co-doping it with 1–7 wt% of Bi and N. The synthesized Bi and N co-doped ZnO nanorod samples showed excellent photocatalytic behavior towards Rhodamine-B (RhB). It was confirmed using XRD and SEM that (5, 2.5) wt.% Bi/N co-doped ZnO nanorods exhibited unique morphology and structure. EDX successfully assessed the elemental composition of the synthesized samples. To provide further insight into its microstructure, the HRTEM and SAED analysis were performed. Optical properties were determined using PL and UV–Visible spectroscopy. The prepared nanorod material degraded almost 89% of RhB in 180 min. The superior degradation ability of co-doped ZnO material when exposed to visible portion of sunlight spectrum is credited to the decrease in the recombination rate of charges and an increase in the depth penetration of photons. The degradation efficiency of Bi/N co-doped ZnO material is enhanced due to reduced recombination rate and increased production of number of defects and oxygen vacancies .
研究领域:
材料科学
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环境科学
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化学
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纳米技术
✓ 已验证
产品关联
DOI
高影响因子
FlatChem
·
2023
·
IF 6.2
Xia Xu,Changchun Chen,Lingxiu Shu,Cheng Cheng,Zhonghai Tang,Yifeng Wang,Lin Pan,Zishen Guan
Water pollution can be efficiently treated by semiconductor photocatalysts under sunlight irradiation. In this study, novel S-scheme SrTiO 3 /ZnIn 2 S 4 composites were successfully fabricated via a facile oil-bath method. And the synthesized samples were then characterized by various characterization techniques together with Density Functional Theory (DFT) calculation. The X-Ray Diffraction(XRD)patterns show that SrTiO 3 /ZnIn 2 S 4 composites are composed of cubic perovskite structure SrTiO 3 and hexagonal phase ZnIn 2 S 4 . The High Resolution Transmission Electron Microscope(HRTEM)and Field Emission Scanning Electron Microscope (FESEM) images showed the intimate contacts between SrTiO 3 and ZnIn 2 S 4 are established to form the heterojunction. The photocatalytic activity of the composite was excellent when degrading organic pollutants, which outperformed that of pristine SrTiO 3 and ZnIn 2 S 4 . The prepared SrTiO 3 /ZnIn 2 S 4 -33% composite sample was proved to have the best photocatalytic activity, with 98 % degradation of organic pollutants under 32 min. The ·O 2 – is the main active reaction species for the degradation of organic pollutants, which was demonstrated by free radical trapping experiment. In addition, the mineralization of organic pollutants during the degradation process was analyzed by Total Organic Carbon (TOC) test. According to a series of experimental and theoretical calculations, the S-scheme heterojunction formed in the SrTiO 3 /ZnIn 2 S 4 composite is put forward for comprehending the photocatalytic degradation of organic pollutants and the formation of free radicals.
研究领域:
环境科学
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材料科学
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化学
✓ 已验证
产品关联
DOI
高影响因子
RSC Advances
·
2016
·Vol. 7
·期 1
·318-326
·
IF 3.289
Pham Van Trinh,Nguyen Ngoc Anh,Bui Hung Thang,Le Dinh Quang,Nguyen Tuan Hong,Nguyen Manh Hong,Phan Hong Khoi,Phan Ngoc Minh,Phan Ngoc Hong
In this study, nanofluid based ethylene glycol (EG) containing Cu nanoparticles decorated on a Gr–MWCNT hybrid material (Gr–MWCNT/Cu) was synthesized successfully for the first time via a chemical reduction method. The SEM, HRTEM, FTIR and XRD studies revealed that Cu nanoparticles with an average diameter of 18 nm were well decorated on the surface of both MWCNTs and graphene sheets. The nanofluids containing Gr–MWCNT/Cu material showed good stability and a maximum thermal conductivity enhancement of 41% at 60 °C for the nanofluid containing 0.035 vol% material compared to EG alone. The enhancement is due to the combination of the high thermal conductivity of graphene, CNT and Cu nanoparticles as well as the higher surface area of the Gr–MWCNT/Cu hybrid structure. Experimental results of thermal conductivity were evaluated using different theoretical models, amongst which the Hamilton–Crosser model was found suitable for predicting the thermal conductivity of the nanofluid.
研究领域:
材料科学
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纳米技术
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热工程
✓ 已验证
产品关联
DOI
高影响因子
FUEL
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2022
·
IF 8.035
Xiaojun Dai,Yan Cheng,Meng Si,Qiang Wei,Dongdong Chen,Wenbin Huang,Yasong Zhou
A series of SAPO-11 molecular sieves were synthesized in the concentrated gel system by reducing the water content in the synthesis system. With SAPO-11 molecular sieves as supports, NiW-supported catalysts were prepared for the hydroisomerization of n-hexadecane. SAPO-11 molecular sieves and catalysts were characterized by XRD, SEM, N 2 adsorption–desorption, NH 3 -TPD, Py-IR, HRTEM and XPS. The results showed that reducing the water content in the synthesis system could increase the mesoporous volume of SAPO-11 molecular sieve and improve the acidity of SAPO-11. For the corresponding catalysts, using SAPO-11 synthesized in concentrated gel system as the support weakened the interaction between the active phase and the support, and increased the dispersion and stacking number of the active phase, which effectively improved the catalytic performance of the catalyst. The yield of i-hexadecane of the catalyst NiW/45W-SA corresponding to SAPO-11 synthesized in conventional water content system was 28.14%, while that of the catalyst NiW/5W-SA corresponding to SAPO-11 synthesized in concentrated gel system was 52.24%. According to the distribution of isomers, it is inferred that hydroisomerization of n-hexadecane over NiW/SAPO-11 follows the pore-mouth mechanism.
研究领域:
催化
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材料科学
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化学工程
✓ 已验证
DOI
高影响因子
JOURNAL OF MATERIALS SCIENCE
·
2019
·Vol. 55
·期 7
·2741-2749
·
IF 3.442
Meng Cheng,Li Wenqi,Ren Chunrong,Zhao Junchuan
Powellite ceramic represents a waste form matrix material to immobilize minor actinides and Mo from reprocessed UMo nuclear fuel. In this paper, the Ca 1−x Li x/2 Gd x/2 MoO 4 (0 ≤ x ≤ 1) series is prepared by solid-state reaction using Gd 3+ as trivalent minor actinide (Cm 3+ ) surrogate, and the structure/microstructure is characterized by XRD, HRTEM, Raman spectroscopy and SEM. Rietveld refinements show that the couple (Gd 3+ and Li + ) enters into the eightfold coordinated Ca site of the powellite structure. With the increase in the contents of Gd and Li, Raman bands broaden due to the distortion of MoO 4 tetrahedra and disordered arrangements of Gd 3+ and Li + . The chemical durability analyzed by the PCT-B indicates that the leaching behaviors of Gd and Mo are related to the interfacial dissolution–reprecipitation mechanism. For the Ca 0.5 Li 0.25 Gd 0.25 MoO 4 ceramic, 7-day NL Gd and NL Mo are shown in the order of ~ 10 −4 and ~ 10 −4 g m −2 , respectively. Thus, our initial results of the structure and chemical durability will provide insights to design new single- or multiphase waste forms for the Mo-rich HLW conditioning.
研究领域:
材料科学
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核工程
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化学工程
✓ 已验证
DOI
高影响因子
FUEL PROCESSING TECHNOLOGY
·
2019
·
IF 4.507
Xiaoping Wu,Qiao Zhang,Lungang Chen,Qiying Liu,Xinghua Zhang,Qi Zhang,Longlong Ma,Chenguang Wang
The development of thermally stable Pt-based catalysts with superior performance for propane dehydrogenation reactions remains a daunting challenge. In this study, a series of PtSn-Mg(Zn)AlO catalysts with different Zn and Pt contents were synthesized by the anion-exchange method for the propane dehydrogenation reaction. To investigate the influence of Zn on the reaction performance and the catalyst structure, the prepared catalysts were characterized with several analytical techniques, including XRD , TEM, HRTEM, H 2 -TPD and CO pulse chemisorption . A good propane conversion (initially higher than 55% and averaging 45.2% over a period of 2 h) and propene selectivity (higher than 99%) were obtained experimentally with PtSn-Mg(3Zn)AlO at 550 °C. The results demonstrated that Pt provided the active sites and that Zn was a promoter. The HRTEM and CO pulse chemisorption results indicated that the addition of Zn to the PtSn-MgAlO catalyst can stabilize the dispersion of metal particles and thus inhibit the sintering of Pt particles. Furthermore, the activities of the used catalysts were almost recovered through reaction-regeneration cycles with the burning-off of coke during five cycles.
研究领域:
催化
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化工
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材料科学
✓ 已验证
DOI
高影响因子
ENERGY & FUELS
·
2023
·
IF 5.3
Xiaojun Dai,Yan Cheng,Tingting Liu,Lingjuan Mao,Qiang Wei,Yasong Zhou
SAPO-11 molecular sieves with different crystal sizes and particle sizes, especially nanosized small-crystal SAPO-11 molecular sieves, were successfully synthesized, and the corresponding NiWS-supported catalysts were prepared for the hydroisomerization of n-hexadecane. XRD, SEM, N2 adsorption–desorption, Py-IR, and HRTEM were used to analyze the effects of crystal size and particle size of the supports on their physicochemical properties, active phase properties, and catalytic performance of the catalysts. Through reaction evaluation and analysis of isomeric products, the effects of the size change of the support on the hydroisomerization performance of the catalyst and the hydroisomerization depth of n-hexadecane were determined. Through comprehensive analysis of the cracking products, it was determined that secondary cracking occurred when the conversion of n-hexadecane on the NiW/SAPO-11-S catalyst reached about 42.7%, and the secondary isomerization occurred when the conversion of n-hexadecane reached about 80%. The hydroisomerization reaction network of n-hexadecane over the NiWS/SAPO-11 catalyst was studied emphatically, and it was found for the first time that the secondary cracking of n-hexadecane during hydroisomerization followed the C3-β-scission mechanism.
研究领域:
化学工程
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催化
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材料科学
✓ 已验证
DOI
高影响因子
CERAMICS INTERNATIONAL
·
2019
·
IF 3.45
Cheng Meng,Wenqi Li,Chunrong Ren,Junchuan Zhao
Powellite ceramic represent one candidate to immobilize minor actinides and Mo from reprocessed UMo nuclear fuel. In this work, the Ca 1-x Li x/2 Ce x/2 MoO 4 (0 ≤ x ≤ 1) series is prepared via a solid-state reaction using Ce 3+ as trivalent minor actinide (Am 3+ ) surrogate, with structure/microstructure characterized by XRD , XPS, HRTEM , and SEM as well. The Ca 1-x Li x/2 Ce x/2 MoO 4 (0 ≤ x ≤ 1) compositions crystallize in tetragonal and are isostructural with scheelite. Rietveld refinements show that Ce 3+ and Li + simultaneously enter into the eight-fold coordinated Ca site of powellite crystal. The chemical durability of powellite phases is evaluated by the ASTM C1285-14 product consistency test method B. The leaching behaviours of Ce and Mo are accordance with the interfacial dissolution-reprecipitation mechanism. For all the Ca 1-x Li x/2 Ce x/2 MoO 4 (0 ≤ x ≤ 1) ceramics, 7-days NL Ce and NL Mo are found to be in the order of 10 −3 -10 −5 g·m −2 and 10 −2 -10 −4 g·m −2 respectively, which exhibit the great retention of Ce and Mo. Interestingly, the values of 7-days NL Ce and NL Mo are predominantly controlled by the distortion of MoO 4 tetrahedra and disordered arrangements of Ce 3+ and Li + . Thus, our initial understanding on the structure and chemical durability relation will provide insight to design new waste forms for the Mo-rich HLW condition.
研究领域:
材料科学
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核废料管理
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陶瓷工程
·
化学工程
✓ 已验证
DOI
高影响因子
CERAMICS INTERNATIONAL
·
2020
·
IF 3.83
Faqiang Shi,Zhonghua Li,Limeng Liu,Jiandong Wu,Jinfu Ma,Yujin Wang
In previous works, it was found hard to synthesize “phase pure” ζ-Ta 4 C 3-z at relatively low temperatures even by prolonged heating, though ζ-Ta 4 C 3-z was believed stable till decomposition at ~2130°C. When the samples were subjected to TEM , vast richness of locally disordered structures in close relation with stacking of the close-pacted Ta-atom planes was observed. Although kinetic factors including diffusion of C atoms/vacancies and re-stacking of the Ta-atom planes explain the densely disordered structures, the richness of local disorders is a scenario that shows cohabitant of the cubic, rhombohedral, and hexagonal structures in a single grain, i.e. formation of a “hybrid grain” consisted of the three symmetries, indicating a transitional or intermediate stage before complete formation of the final phase of rhombohedral ζ-Ta 4 C 3-z . This time tantalum carbide ceramics TaC x with C:Ta atomic ratios x = 0.66 and 0.7 were prepared by reaction hot pressing of TaC and Ta powder mixtures. 5–30 mol% Cu/Ag additives and heat treatments were used to reproduce “hybrid grains” to facilitate further TEM and HRTEM observations on the disordered hybrid grains to argue for the transitional/intermediate stage. The cohabitant cubic, rhombohedral, and hexagonal structures in single grains may also help explain the difficulty in identification of the various phases by XRD in the transitional/intermediate stage of ζ-Ta 4 C 3-z reaction. Microstructural evolution and fracture toughness of the composites were also investigated.
研究领域:
材料科学
·
陶瓷
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纳米材料
·
固体化学
✓ 已验证
产品关联
DOI
高影响因子
APPLIED SURFACE SCIENCE
·
2022
·
IF 7.392
Yi Wen,Zheng Huang,Min Zhao,Longshan Zhao
The discharge of industrial heavy metal wastewater not only leads to environmental pollution, but also harms human health, so it is imperative to control heavy metal pollution. In the current work, a sequence of anatase/brookite TiO 2 @COF with different mass ratios, bi-phase TiO 2 and bare COF were successfully synthesized by simple hydrothermal synthesis. The photocatalytic activity of the prepared catalysts was assessed by reducing Cr(Ⅵ) in model pollutant (K 2 Cr 2 O 7 ). Under the condition of pH = 3, the Cr(Ⅵ) reduction rate of TiO 2 @COF-4 was as high as 99.19% in 30 min. The photocatalytic activity of TiO 2 @COF-4 remained stable in four consecutive cycles, suggesting that it has a potential application prospect for the removal of Cr(Ⅵ) in the actual environment. The morphology and structure of photocatalysts were observed by different techniques (SEM/EDS, HRTEM, BET analysis, XRD, FTIR and XPS). The specific reasons for the enhancement of photocatalytic performance of materials were explored by different methods (PL, UV–vis DRS, Mott-Schottky plots, I-T curves and EIS). Finally, we concluded that the photocatalytic system of TiO 2 @COF-4 may follow the typical direct Z- scheme mechanism. This work provides an effective solution for the water treatment of heavy metal pollution.
研究领域:
环境科学
·
材料科学
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化学工程
·
纳米技术
✓ 已验证
产品关联
DOI
高影响因子
SENSORS AND ACTUATORS B-CHEMICAL
·
2023
·
IF 8.4
Lanlan Guo,Yanji Feng,Feng Shi,Wei Zhao,Hua Zeng,Tingyu Chen,Yingli Yang,Guodong Wang,Xiaolian Liu,Yan Wang,Xueli Yang
In this work, pure NiO, Al-doped NiO, W-doped NiO and a series of Al/W co-doped NiO nanoflowers were successfully prepared through a simple solvothermal method . Various characterization methods, such as XRD , SEM, TEM, HRTEM and XPS , were used to confirm the physical and chemical properties of the sensitive materials in terms of micro-nano structures, compositions and elemental distributions. The as-obtained Al/W co-doped NiO showed a nanoflower structure with an approximate size of ∼ 200 nm. What's more, among six sensors constructed from the sensitive materials, the sensor based on 3 at% Al 3+ /3 at% W 6+ co-doped NiO (3Al3W-NiO) achieved the highest response (R g /R a =112) toward 100 ppm triethylamine with a low detection limit (1 ppm) at 325 ℃. Besides, this sensor also exhibited excellent response/recovery characteristics and long-term stability. These favorable sensing performances of the 3Al/3 W co-doped NiO sensor are not only modulated by the initial resistance (R a ), but are also closely related to the large specific surface area , porous structures , low crystallinity , rich oxygen vacancies and high Ni 3+ /Ni 2+ ratio in the composite nanomaterials.
研究领域:
材料科学
·
纳米技术
·
化学传感器
·
气体传感
✓ 已验证
DOI
高影响因子
危险品化学品经营许可证（带存储）