APPLIED SURFACE SCIENCE
·
2022
·
IF 7.392
Yan Wu,Tao Liu,Bin Ji,Wei Wang
Iron-cobalt alloy is a potential and economical magnetostrictive material, however, our microscopic understanding of the co-electrodeposition process of Fe-Co alloys is still unsatisfactory. In this work, a flat Fe-Co film with 10 μm was successfully prepared by electrodeposition with a non-toxic sulfate solution. The effects of (NH 4 ) 2 SO 4 , an important additive, were studied and DFT calculation was used to analyze the mechanism of (NH 4 ) 2 SO 4 . EIS shows that (NH 4 ) 2 SO 4 can promote the Fe-Co co-deposition process and obviously inhibits the hydrogen evolution reaction. In addition, (NH 4 ) 2 SO 4 can significantly reduce the internal stress of the Fe-Co film by 110,000 MPa, so that the cracks caused by the internal stress are obviously removed. The results of quantum chemistry calculation further show that NH 4 + is more inclined to adsorb on Fe-Co surface than H 2 O and H + , which reduces the hydrogen evolution on the electrode surface. The results are beneficial to improve the Fe-Co co-deposition process, reduce the internal stress and to prepare a high-performance Fe-Co magnetic film. The films will be assembled on the electronic devices with sensors.
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DOI
高影响因子
MOLECULES
·
2023
·Vol. 28
·期 10
·4091
·
IF 4.6
Jia-Yao Chen,Xue-Wen Zhang,Tian-Yu Wu,Hai-Mu Ye
Crystalline/crystalline blends of polymer have shown advantages in the preparation of new polymeric materials. However, the regulation of co-crystallization in a blend is still full of challenges due to the preferential self-crystallization driven by thermodynamics. Here, an inclusion complex approach is proposed to facilitate the co-crystallization between crystalline polymers, because the crystallization process displays a prominent kinetics advantage when polymer chains are released from the inclusion complex. Poly(butylene succinate) (PBS), poly(butylene adipate) (PBA) and urea are chosen to form co-inclusion complexes, where PBS and PBA chains play as isolated guest molecules and urea molecules construct the host channel framework. The coalesced PBS/PBA blends are obtained by fast removing the urea framework and systematically investigated by differential scanning calorimetry, X-ray diffraction, proton nuclear magnetic resonance and Fourier transformation infrared spectrometry. It is demonstrated that PBA chains are co-crystallized into PBS extended-chain crystals in the coalesced blends, while such a phenomenon has not been detected in simply co-solution-blended samples. Though PBA chains could not be totally accommodated in the PBS extended-chain crystals, their co-crystallized content increases with the initial feeding ratio of PBA. Consequently, the melting point of the PBS extended-chain crystal gradually declines from 134.3 °C to 124.2 °C with an increasing PBA content. The PBA chains playing as defects mainly induce lattice expansion along thea-axis. In addition, when the co-crystals are soaked in tetrahydrofuran, some of the PBA chains are extracted out, leading to damage to the correlative PBS extended-chain crystals. This study shows that co-inclusion complexation with small molecules could be an effective way to promote co-crystallization behavior in polymer blends.Keywords:co-crystal;polyester;blend;inclusion complex;thermal property
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DOI
PubMed
高影响因子
NEW CARBON MATERIALS
·
2021
·
IF 1.905
Jing Zhang,Lianghao Song,Chenfei Zhao,Xiuping Yin,Yufeng Zhao
Although the Co and N co-doped carbon catalyst (Co-NC) has attracted much attention because of its low cost and the natural abundance of the dopants, it has a low oxygen reduction reaction (ORR) activity and a high selectivity for the two-electron (2e - ) reduction of oxygen to H 2 O 2 , which affects its use in fuel cells. Co-NC catalysts were prepared by the pyrolysis of a mixture of cobalt chloride and chitosan pretreated with zinc chloride at 650, 750 and 850 o C, followed by washing with nitric acid and annealing at 900 o C. The results indicate that zinc chloride helps the complexing of chitosan with Co 2+ , which is also a chemical activator that generates pores, and annealing caused the evaporation of the spherical Zn metal nanoparticles formed by the carbothermal reduction of Zn ions, leading to a unique porous structure of the catalysts with spherical pores filled with spherical carbon nanoparticles formed by the growth of nitrogen-doped carbon as a result of the Co catalyst. The degree of graphitization is also improved by the Co catalyst. The Co-NC catalyst obtained at a pyrolysis temperature of 750 o Cshows the same four-electron (4e - ) reduction of oxygen as a commercial Pt/C catalyst, and a significantly higher ORR catalytic activity, longer-term stability and better methanol tolerance than a commercial Pt/C catalyst. These are due to its large specific surface area, high contents of pyridinic nitrogen and graphitic nitrogen that disperse the Co species and its excellent electrical conductivity.
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高影响因子
Nanomaterials
·
2021
·Vol. 11
·期 5
·1245
·
IF 5.076
Zehui Peng,Shuai Lou,Yuan Gao,Lijun Kong,Shancheng Yan,Ka Wang,Haizeng Song
There are abundant water resources in nature, and hydrogen production from electrolyzed water can be one of the main ways to obtain green and sustainable energy. Traditional water electrolysis uses precious metals as catalysts, but it is difficult to apply in massive volumes due to low reserves and high prices. It is still a challenge to develop hydrogen electrocatalysts with excellent performance but low cost to further improve the efficiency of hydrogen production. This article reported a potential candidate, the Co-NiS2/CoS2(material is based on NiS2, and after Co doping, The NiS2/CoS2heterostructure is formed) heterostructures, prepared by hydrothermal method with carbon paper as the substrate. In a 0.5 M sulfuric acid solution, the hydrogen evolution reaction with Co-NiS2/CoS2as the electrode showed excellent catalytic performance. When the Co (Cobalt) doping concentration is increased to 27%, the overpotential is −133.3 mV, which is a drop of 81 mV compared with −214.3 mV when it is not doped. The heterostructure formed after doping also has good stability. After 800 CV cycles, the difference in overpotential is only 3 mV. The significant improvement of the catalytic performance can be attributed to the significant changes in the crystal structure and properties of the doped heterostructures, which provide an effective method for efficient electrocatalytic hydrogen production.Keywords:hydrogen evolution reaction;catalysts;heterostructures;transition metal dichalcogenides
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高影响因子
INTERNATIONAL JOURNAL OF BIOLOGICAL MACROMOLECULES
·
2020
·
IF 5.162
Sizhu Ren,Ziyuan Wang,Muhammad Bilal,Yuxiao Feng,Yunhong Jiang,Shiru Jia,Jiandong Cui
Multienzymatic conversion of carbon dioxide (CO 2 ) into chemicals has been extensively studied. However, regeneration and reuse of co-factor are still the main problems for the efficient conversion of CO 2 . In this study, a nanoscale multienzyme reactor was constructed by encapsulating simultaneously carbonic anhydrase (CA), formate dehydrogenase (FateDH), co-factor (NADH), and glutamate dehydrogenases (GDH) into ZIF-8. In the multienzyme reactors, cationic polyelectrolyte (polyethyleneimine, PEI) was doped in the ZIF-8 by dissolving it in the precursors of ZIF-8. Co-factor (NADH) was anchored in ZIF-8 by ion exchange between PEI (positive charge) and co-factor (negative charge), and regenerated through GDH embedded in the ZIF-8, thus keeping high activity of FateDH. Activity recovery of FateDH in the multienzyme reactors reached 50%. Furthermore, the dissolution of CO 2 in the reaction solution was increased significantly by the combination of CA and ZIF-8. As a result, the nanoscale multienzyme reactor exhibited superior capacity for conversion of CO 2 to formate. Compared with free multienzyme system, formate yield was increased 4.6-fold by using the nanoscale multienzyme reactor. Furthermore, the nanoscale multienzyme reactor still retained 50% of its original productivity after 8 cycles, indicating excellent reusability.
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PubMed
高影响因子
AICHE JOURNAL
·
2020
·Vol. 66
·期 5
·e16923
·
IF 3.519
Jian Zhang,Liang Wang,Zhiyi Wu,Hai Wang,Bingsen Zhang,Feng-Shou Xiao
We report mesoporous Co-Al oxide nanosheets (Co x Al-Ns, where x denotes the Co/Al ratio in the samples) prepared by calcination of CoAl-hydrotalcite and subsequent alkaline treatment. X-ray diffraction, scanning electron microscopy, transmission electron microscopy, and X-ray photoelectron spectroscopy measurements show that the prepared Co-Al oxide nanosheets (Co x Al-Ns) are very thin (10–15 nm) and exhibit high mesoporosity (3–5 nm). Catalytic CO oxidation tests reveal that the Co x Al-Ns exhibit excellent catalytic performances at relatively low temperatures: for example, the Co 2.5 Al-Ns catalyst could achieve 99% CO conversion at −98°C. Kinetic studies and experimental investigations indicate that the high activity of the Co 2.5 Al-Ns sample is strongly related to the abundance of active sites associated with the large Brunauer–Emmett–Teller surface area. The Co 2.5 Al-Ns catalyst also achieves full conversion of CO in tests performed with a gas mixture simulating automobile exhaust gas at 200°C. After loading the Co 2.5 Al-Ns on a porous ceramic substrate, the obtained Co 2.5 Al-Ns/PC shows high activity and stability in CO oxidation process. These features are potentially important for future industrial applications of these catalysts.
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高影响因子
JOURNAL OF ALLOYS AND COMPOUNDS
·
2025
·
IF 6.3
Cheng Lv,Jiayan Huang,Yuang QI,Qingjie He,Yazhou Wang,Cuili Xiang,Yongjin Zou,Fen Xu,Lixian Sun
MgH₂ is one of the most promising materials for solid hydrogen storage and is environmentally friendly primarily owing to its high mass hydrogen storage density (7.6 %). However, the application and development of MgH₂ are limited by its sluggish kinetics, requiring high processing temperatures. In this study, we prepared Ni/Co-co-doped Ti 2 VC 2 bimetallic MXene nanosheets via etching and the hydrothermal method. These nanosheets were then doped into MgH₂, resulting in drastically improved hydrogen storage properties. The MgH₂-based composite hydrogen storage materials doped with 10 wt% Ni/Co–Ti 2 VC₂ (TVCNC) commenced hydrogen emission from 183 °C and could emit 6.65 wt% hydrogen at 300 °C. During the rehydrogenation test, the composites could still absorb hydrogen at 5.0 wt% within a 10 min window at a hydrogen pressure of 20 bar at 125 °C. Moreover, the hydrogen absorption and emission kinetics of the doped MgH₂ were considerably improved. This improvement could be ascribed to the significantly increased specific surface area of the MXene nanosheets after etching, which increased the number of active sites on the surface to accelerate the reaction, thereby accelerating hydrogen adsorption and emission. In addition, the migration of electrons between the multivalent Ti ions as well as between Ni and Co helped accelerate bond cleavage between magnesium and hydrogen, thereby enhancing the kinetic properties. Ni/Co co-doping produced Mg 2 Ni alloys with magnesium via hydrogen adsorption and emission, thus improving the reaction kinetics of the composites.
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高影响因子
JOURNAL OF THE CHINESE CHEMICAL SOCIETY
·
2020
·Vol. 67
·期 10
·1818-1826
·
IF 1.554
Yang Hu,Longchao Du,Cun Li,Jiale Shen,Weiju Zhu,Chenxi Shao
Carbon dioxide (CO 2 ) is an easily available renewable carbon source that can be used as a comonomer in the catalytic ring-opening polymerization of epoxides to form aliphatic polycarbonates. Herein, a series of new Salen-Co(III) bifunctional catalysts were synthesized for the first time, and they were studied to catalyze the copolymerization of CO 2 and propylene oxide (PO)/cyclohexene oxide (CHO). At the same time, the effects of reaction conditions (electronic effect, temperature, time) on catalytic activity and selectivity were investigated. The results show that the Salen-Co(III) complexes with electron-withdrawing groups have higher selectivity and activity for propylene carbonate (PPC)/cyclohexylene carbonate (PCHC). At the same time, the Salen-Co(III) complexes can better catalyze the copolymerization of CHO and CO 2 than that of PO and CO 2 . The catalytic efficiency of the four complexes increased with increasing temperature, and the best reaction condition is 80°C, 30 min and 2 MPa of CO 2 .
研究领域:
化学催化
·
材料科学
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高影响因子
MICROCHEMICAL JOURNAL
·
2020
·
IF 3.594
Rui Zhao,Xingxing Wu,Yuxiang Gao,Yani Liu,Jiaojiao Gao,Yimai Chen,Zhou Zheng,Wei Gan,Qunhui Yuan
The first trial for electrochemical determination of Pb(II) with a bimetal organic framework derived composite, denoted as Co-N x -C@MWCNTs, is demonstrated in this work. The Co-N x -C@MWCNTs with three dimensionally braided structure was fabricated on the basis of zinc/cobalt co-centered bimetal zeolite imidazole framework (BMZIF-67) and interlaced with multi-walled carbon nanotubes (MWCNTs). Contributable to the presence of zinc/cobalt co-centers and the nitrogen-containing ligands, the homogenous dispersion of metallic cobalt and the formation of Co-N x moieties which were widely known as active sites in electrocatalysts were fulfilled. The integration of MWCNTs resulted in enhanced conductivity and extra porosity, which were also crucial for electrochemical sensing. Therefore, Co-N x -C@MWCNTs based electrochemical sensor exhibits good reliability for Pb(II) detection, with a low detection limit of 0.7 μg L −1 over a wide linear range of 2–60 μg L −1 . This design may shed lights on the fabrication of bimetal organic frameworks based electrochemical sensors in general.
研究领域:
材料科学
·
环境科学
·
分析化学
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高影响因子
ELECTROCHIMICA ACTA
·
2020
·
IF 6.215
Na Ye,Zhao Jiang,Tao Fang
Direct methanol fuel cells (DMFCs) have attracted extensive attention due to clean, efficient characteristics and portable applications. In this work, a series of Pd x Cu y /reduced graphene oxide (rGO) catalysts are assembled and the catalytic performances are investigated for methanol oxidation reaction (MOR) in alkaline media. The intrinsic surface electronic structures of the Pd x Cu y /rGO bimetallic catalysts are also studied to clarify the reaction mechanism. The results reveal that Pd 1.2 Cu 0.2 /rGO exhibits superior catalytic activity (1101.58 A g Pd −1 ), 4.2 and 5.2 times higher than those of the commercial PtRu/C and Pd/C catalysts. CO stripping suggests that the onset potential for CO oxidation on the Pd 1.2 Cu 0.2 /rGO catalyst is lower than those on the commercial PtRu/C and Pd/C catalysts, implying that the anti-CO poisoning ability is enhanced. Combined with the analysis of X-ray diffraction (XRD), high-resolution transmission electron microscopy (HRTEM), X-ray photoelectron spectroscopy (XPS) and Raman, the enhanced catalytic activity and anti-CO poisoning ability are attributed to the charge transfer and lattice compression between Pd and Cu, which modify the d-band center and weaken the adsorption of CO. Furthermore, a volcano plot is found between the MOR activity and d-band center, indicating that the excellent MOR activity is attributed to the optimal d-band center with the moderate adsorption strength of CO-like intermediates.
研究领域:
材料科学
·
电化学
·
催化反应
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高影响因子
JOURNAL OF CATALYSIS
·
2018
·
IF 6.759
Houlin Wang,Shuting Luo,Meisheng Zhang,Wei Liu,Xiaodong Wu,Shuang Liu
Though the catalytic oxidation of CO, NO and soot over CeO 2 could be understood within a similar Mars-van Krevelen-type mechanism, these reactions were likely to be driven by different active phases. In this work, several CeO 2 and Ag/CeO 2 nanorods with different contents of surface oxygen vacancies (V O-s ) and active oxygen species (O x − ) were designed as model catalysts. Their catalytic performance indicated that, CO oxidation was determined by pre-existing ceria V O-s , while O x − participated in NO and soot oxidation directly. Besides, by loading silver onto the high-temperature aged CeO 2 nanorods, Ag/CeO 2 catalysts with high availability of ceria lattice oxygen were obtained, whose low-temperature oxidation activity was proven comparable to that of the platinum catalysts. In this sense, the model designing in this work not only provided methods to find out proper reactivity descriptors, but also conferred low-cost catalysts with high practical potential.
研究领域:
催化
·
材料科学
·
化学工程
·
环境化学
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高影响因子
Journal of Macromolecular Science Part B-Physics
·
2022
·
IF 1.366
Zemei Fang,Zhihua Zhou,Wei Wu,Wenjuan Liu,Hailin Xie,Hongbo Hu,Yan Gan,Jianjun Fang
A degradable blend scaffold composed of poly(D,L-lactide-co-glycolide-co-ε-caprolactone) (PLLGC) and ethanediamine modified poly(lactide-co-glycolide) (EMPLGA) was prepared by using a thermally induced phase separation technique. The morphologies of the PLLGC/EMPLGA blend scaffolds were characterized by using scanning electron microscopy (SEM). The in-vitro degradation behaviors and biocompatibility of the individual components and the blend were investigated by using rat L929 cells. The blend scaffolds showed a porous and well interconnected pore structure. The degradation rate sequence of the three scaffolds, the individual components and the blend, was EMPLGA > PLLGC/EMPLGA > PLLGC. The PLLGC/EMPLGA blend scaffold was non-cytotoxic and showed high cell proliferation.
研究领域:
生物材料
·
组织工程
·
高分子科学
·
生物医学工程
·
体外降解
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高影响因子
危险品化学品经营许可证（带存储）