OPTICAL MATERIALS
·
2022
·
IF 3.754
Shaofeng Liang,Muqun Wang,Wei Gao,Xia Zhao
Hydrothermal methods are commonly used to synthesize carbon dots (CDs), but the synthesized CDs have the disadvantage of low quantum yields. In this paper, we used acid treatment, elemental doping, and passivation to treat the CDs, which could increase the quantum yield from 36% to 42%, 61% and 68%, respectively, and the doping and passivation treatments resulted in red-shifted and blue-shifted emission behavior of the CDs. The optical properties , morphology and chemical structure of CDs are analyzed to investigate the reasons for the quantum yield increase and the mechanism of excitation dependent emission (EDE) and excitation independent emission (EIE). The increase of quantum yield is mainly due to the increase of pyridine N content. The different optical behaviors depend mainly on the surface states of CDs. C–OH and C–O–C can create new energy levels leading to the appearance of EDE properties. C=O is an electron-absorbing group that weakens the conjugation effect leading to blue shift.
研究领域:
材料科学
·
光学
✓ 已验证
DOI
高影响因子
CHEMICAL PHYSICS LETTERS
·
2018
·
IF 1.686
Shiyu Zuo,Haiming Xu,Wei Liao,Lei Sun,Qiang Li,Jie Zan,Binyang Zhang,Dongya Li,Dongsheng Xia
In this study, g-C 3 N 4 Cu 2 O was successfully synthesized in the presence of PEG-400 surfactant via an acid treatment hydrothermal method and a high-temperature calcination method. The structures and properties of as-synthesized samples were characterized using a range of techniques, such as XPS, TEM, PL and BET. The g-C 3 N 4 Cu 2 O heterojunction exhibits the enhanced photocatalytic performance and high stability. It is revealed that the addition of PEG can promote the heterojunction effect of g-C 3 N 4 Cu 2 O, effectively improving the crystallinity and specific surface area of the photocatalyst, separation efficiency of photocarriers, and light absorption, thus enhancing the photocatalytic performance.
研究领域:
材料科学
·
环境科学
✓ 已验证
DOI
高影响因子
Journal of the Taiwan Institute of Chemical Engineers
·
2023
·
IF 5.7
Chengzhi Hu,Huiping Zhang,Ying Yan
Background Co 3 O 4 shows potential as a cost-effective alternative to precious metal catalysts for VOCs catalytic combustion. However, its catalytic activity requires further enhancement. Methods A new type of paper-like carbon nanotube membrane composite (CNTs/PSSF) was used as a support to prepare Co 3 O 4 -CNTs/PSSF catalysts by metal-organic vapor deposition (MOCVD) and impregnation method (IM) respectively for toluene combustion. Besides, the effects of acid treatment to support on the catalytic activity were investigated. Various characterization techniques, including X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), electron paramagnetic resonance (EPR), and oxygen temperature-programmed desorption (O 2 -TPD), were employed to evaluate the effects of different preparation methods and acid treatment on the structure and catalytic performance mechanism of Co 3 O 4 -CNTs/PSSF. Significant findings The preparation method significantly affects the catalyst's properties and catalytic activity. Compared with IM, the MOCVD-prepared catalysts show stronger coordination of carbon nanotubes, resulting in more oxygen vacancies and surface active oxygen. Additionally, oxygenous groups introduced by HNO 3 form Co-O-C linkage between Co and CNTs, promoting oxygen vacancies and enhancing surface active oxygen content, thereby dramatically improving the catalyst's catalytic activity, especially for HIM-10 whose T 90 is reduced by 140 °C. This work provides insights for enhancing the catalytic combustion activity of cobalt oxide.
研究领域:
环境科学
·
材料科学
✓ 已验证
产品关联
DOI
高影响因子
APPLIED ORGANOMETALLIC CHEMISTRY
·
2018
·Vol. 32
·期 9
·e4448
·
IF 3.581
Shiyu Zuo,Haiming Xu,Wei Liao,Lei Sun,Donghui Han,Jie Zan,Binyang Zhang,Dongya Li,Dongsheng Xia
Acid-treated g-C 3 N 4 -Cu 2 O was prepared by hydrothermal reduction followed by high temperature calcination and acid exfoliation. The structures and properties of as-synthesized samples were characterized using a range of techniques, such as X-ray photoelectron spectroscopy, scanning electron microscopy, Photoluminescence Spectroscopy and the Brunauer–Emmett–Teller (BET) theory. The photocatalytic activity was evaluated by measuring the photodegradation of methyl orange under visible-light irradiation. Based on the results of TEM, XPS, EPR and other techniques, it was verified that a heterojunction was formed. The acid treatment process can increase the specific surface area to form abundant heterojunction interfaces as channels for photo-generated carrier separation, thereby enhancing its light utilization and quantum efficiency. Results indicate that acid-treated g-C 3 N 4 -Cu 2 O possesses a large specific surface area, which provides plentiful activated sites for heterojunctions to form; in addition, it showed a high visible light effect and the minimum charge-transfer resistance. Furthermore, the g-C 3 N 4 -Cu 2 O material exhibits high levels of effectiveness and stability. Electron paramagnetic resonance and a series of radical trapping experiments demonstrate that the holes and •O 2 − could be the main active species in methyl orange photodegradation. This work could provide new insights into the fabrication of composite materials as high-performance photocatalysts, and facilitate their application in addressing environmental protection issues.
研究领域:
材料科学
·
环境科学
✓ 已验证
DOI
高影响因子
INTERNATIONAL JOURNAL OF BIOLOGICAL MACROMOLECULES
·
2017
·
IF 3.671
Binghua Sun,Yaoqi Tian,Benxi Wei,Long Chen,Yanhong Bi,Zhengyu Jin
Potato starch was treated with 0.36% HCl in ethanol and water for various time periods, and its structural changes were evaluated and compared in this study. Acid-ethanol treated starch (AET-s) had relatively low average molecular weight ( M w ) and z-average radius of gyration ( R g ), and its solubility was higher than that of the counterpart acid-water treated starch (AWT-s). The granular appearance and differential scanning calorimetry (DSC) profile demonstrated that acid in ethanol and in water exhibited different attack pathways on the granules. No significant difference in crystallinity was observed for AET-s; however, the ratio of absorbance 1022/995 cm −1 and the peak intensity detected by small-angle X-ray scattering (SAXS) were increased with increasing treatment time. These results suggested that ethanol-acid treatment simultaneously attacked on the amorphous and crystalline regions, and the degradation extent on crystalline regions caused by ethanol-acid treatment was higher than that observed by acid-water treatment.
研究领域:
食品科学
·
生物化学
✓ 已验证
产品关联
DOI
PubMed
高影响因子
RSC Advances
·
2019
·Vol. 9
·期 57
·33147-33154
·
IF 3.049
Jianxiang Sun,Jingqi Ji,Zhigeng Chen,Shumei Liu,Jianqing Zhao
Some commercially available graphene (CG) samples, actually graphite nanoplates, are difficult to be applied in polymers due to their large thickness, even though their fabrication is more cost-effective. In this work, a CG sample with a thickness of about 25 nm is pre-treated via a facile acid soaking technique, and then the acid-treated CG is introduced into epoxy resin (EP) to improve the toughness while maintaining the high rigidity of the EP. The thickness of the acid-treated CG is dramatically decreased to about 1 nm, well-dispersing CG in the EP matrix. The tensile strength and the fracture energy of EP composite with 0.2 wt% acid-treated CG are increased to 85.2 MPa and 3.6 kJ m−2 from 74.3 MPa and 2.3 kJ m−2 of pure EP, respectively. In addition, the tensile-fractured surfaces of EP composites reveal that the toughening mechanism is mainly attributed to the crack deflection and crack pinning caused by the firmly-embedded CG nanosheets in the EP matrix. Besides, the glass transition temperature of EP composites is increased to 170.5 °C from 163.9 °C of pure EP. The present study provides a valuable approach for making use of the cost-effective graphite nanoplates to achieve a similar performance as graphene in EP.
研究领域:
材料科学
·
复合材料
✓ 已验证
DOI
PubMed
高影响因子
CHEMICAL ENGINEERING JOURNAL
·
2019
·
IF 8.355
An Wang,Kanggen Zhou,Xuekai Zhang,Dingcan Zhou,Changhong Peng,Wei Chen
Large amounts of waste acids with high acidity and arsenic levels are produced during pyrometallurgy of nonferrous metal sulfide ores, in which the treatment of arsenic remains a problem. In this study, copper powder was used as a reducing agent and synergized with iodine ions to effectively remove arsenic from waste acids. The influences of stirring speed, copper powder particle size, sodium iodide/copper powder dosages, and reaction temperature on the removal efficiency of arsenic were investigated. The results showed almost complete removal of arsenic under the optimal conditions: 600 rpm stirring speed, copper powder particle size <15 μm, molar ratio I:As = 5, molar ratio Cu:As = 8, reaction temperature 40 °C, and reaction time 90 min. The kinetics studies indicated that arsenic removal was controlled by chemical reaction with apparent activation energy of 42.39 kJ·mol −1 . The morphological and structural characterizations of dearsenization residues showed surface of copper particles with double covering-layers. The interior covering-layer constituted the formation region of As(0), the phases of which were As and As-Cu intermetallic compounds, while the main product formed in exterior covering-layer was identified as CuI.
研究领域:
环境科学
·
冶金工程
✓ 已验证
产品关联
DOI
高影响因子
DALTON TRANSACTIONS
·
2018
·Vol. 47
·期 11
·3864-3871
·
IF 4.099
Aolei Gao,Zhenhua Sun,Shaopeng Li,Xinjuan Hou,Huiquan Li,Qisheng Wu,Xinguo Xi
Li1.6Mn1.6O4 is a representative ion sieve material that is used to recover lithium from salt brines and bitterns owing to its high lithium ion adsorption capacity reaching 11.9–44 mg g−1. However, manganese dissolution during acid treatment hinders the industrial application of the material. For investigating the mechanism of manganese dissolution, the precursor Li1.6Mn1.6O4 and ion sieve H1.6Mn1.6O4 were prepared and characterized using X-ray diffraction (XRD), scanning electron microscopy (SEM), Fourier-transform infrared spectroscopy (FT-IR), chemical content analyses, diffuse reflectance infrared Fourier-transform spectroscopy (DRIFTS), and X-ray photoelectron spectroscopy (XPS). The results of XRD, SEM, and FT-IR showed that the bulk phase of Li1.6Mn1.6O4 retained the spinel structure, whereas the lattice diminished during acid treatment. The results of chemical content analyses showed that the bulk phase of Li1.6Mn1.6O4 contained a few trivalent manganese atoms and that the mean valence of manganese in the material increased during acid treatment. DRIFTS and XPS exhibited that the surface of Li1.6Mn1.6O4 was mostly full of tetravalent manganese and retained the spinel structure during acid treatment. In the proposed mechanism of manganese dissolution, an electron of trivalent manganese in the bulk phase transfers to the surface and is captured by tetravalent manganese within the acidic environment. Then, tetravalent manganese is converted to bivalent manganese after acquiring sufficient electrons, and dissolution occurs simultaneously.
研究领域:
材料科学
·
化学工程
✓ 已验证
DOI
PubMed
高影响因子
ORGANIC ELECTRONICS
·
2018
·
IF 3.68
Qiufeng Meng,Qinglin Jiang,Kefeng Cai,Lidong Chen
PEDOT:PSS coated Te (PC Te) nanorod/PEDOT:PSS composite films were prepared by a drop-casting technique. H 2 SO 4 treatment was employed to enhance thermoelectric (TE) properties of the composite films. The addition of PC Te nanorods increased both the electrical conductivity and the Seebeck coefficient of the composite films. An optimized power factor of 141.9 μW/mK 2 was obtained for the film containing 90 wt% PC Te nanorods treated with 12 M H 2 SO 4 at room temperature , which was 2.75 times as high as that of the untreated composite film, corresponding to the electrical conductivity and Seebeck coefficient of 204.6 S/cm and 83.27 μV/K, respectively. XPS and GIWAXS analysis revealed the removal of insulating PSS units and the rearrangement of PEDOT chains after the H 2 SO 4 treatment. Finally, a 9-leg TE generator prototype was fabricated using the optimized composite film. The maximum output power and area output power density produced from the prototype were 47.7 nW and 57.2 μW/cm 2 , respectively, at the temperature difference of 40 K.
研究领域:
材料科学
·
物理化学
✓ 已验证
DOI
高影响因子
APPLIED SURFACE SCIENCE
·
2015
·
IF 2.711
Ming Wu,Jun-Min Yan,Xue-wei Zhang,Ming Zhao
The g -C 3 N 4 is synthesized by directly heating the acetic acid treatment melamine. A combination of XRD, SEM, TEM, PL and UV–vis are utilized to characterize the composition, morphology and optical properties of g -C 3 N 4 . This method synthesized g -C 3 N 4 shows smaller particles and some holes which high up the photocatalytic activity compared with the bulk g -C 3 N 4 .
研究领域:
材料科学
·
化学
✓ 已验证
产品关联
DOI
高影响因子
CATALYSIS TODAY
·
2020
·
IF 5.825
Yulong Gu,Wei Xu,Yinyong Sun
The development of active oxidative desulfurization (ODS) catalysts is of practical importance. Recently, MOF-808(Zr) has been attempted to use as ODS catalyst due to its various advantages. However, generally MOF-808(Zr) prepared by conventional method was less active in the oxidation reactions due to the lack of defect sites in the structure. In this contribution, we report that the catalytic oxidative performance of MOF-808(Zr) can be enhanced by acid treatment due to the formation of defect sites resulting from the partial removal of organic linkers in the structure. During the experiment, the effect of acid concentration, treatment time, the addition amount of oxidant and reaction parameters on the performance of MOF-808(Zr) was studied. The catalytic results show that MOF-808(Zr) treated with 0.4 M HCl for 1h can catalyze the oxidation of dibenzothiophene completely at 60°C in 15 min. The activity (mole number of converted DBT per hour per unit mass) is 70 mmol h −1 g −1 , which is much higher than that (45 mmol h −1 g −1 ) of parent MOF-808(Zr). In addition, the catalyst can be reused several times without obvious loss of catalytic performance.
研究领域:
材料科学
·
催化化学
✓ 已验证
DOI
高影响因子
Journal of Materials Chemistry C
·
2025
·
IF 5.1
Li Wang,Xiawen Peng,Chen Zhang,Xiaojun Zeng,Haitao Feng,Yanfeng Gao
Porous carbon is considered an excellent candidate material for electromagnetic wave absorption (EMWA) applications due to its distinctive microstructure. Herein, a series of porous carbon were synthesized by carbonizing sodium alginate powders at different temperatures (700 ℃, 800 ℃, and 900 ℃), followed by hydrochloric acid treatment. During the carbonization process, sodium ions in sodium alginate induce the formation of a porous structure by transforming into Na2CO3, which serves as a templating agent and an etching agent. The porous carbon prepared at 800 ℃ with a filler loading of 10 wt% exhibits a minimum reflection loss of -61.81 dB at a thickness of 5.10 mm and a maximum effective absorption bandwidth (EABmax) of 4.21 GHz at a thickness of 5.50 mm. In addition, the porous carbon prepared at 900 °C achieves a EABmax of 4.46 GHz at a thickness of 1.7 mm. Those outstanding EMWA performances mainly stem from the synergistic effects of interface polarization, dipole polarization, conductive loss, and microstructure. This work provides a straightforward and eco-friendly approach for the large-scale fabrication of porous carbon with excellent EMWA performance.
研究领域:
材料科学
·
电磁学
✓ 已验证
产品关联
DOI
高影响因子
危险品化学品经营许可证（带存储）