MATERIALS CHEMISTRY AND PHYSICS
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2021
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IF 4.094
Faqiang Shi,Limeng Liu,Jiandong Wu,Junfeng Hou,Yujin Wang
TaC x (x = 0.5, 0.55, 0.6 and 0.7) ceramics with 20 mol% Al addition were prepared by hot pressing TaC, Ta and Al powder mixtures. Effects of the overall C:Ta ratios and the Al addition on constituent phases, microstructures and mechanical properties of the consolidated materials were examined. Results showed that O impurity contained in the starting powders was collected in form of Al 2 O 3 due to strong affinity of O with Al. The TaC x -Al composites were easy to densify due to presence of molten Al at its melting point ( T m = 660 °C) and a transient Al–Ta eutectic liquid at higher temperatures. After densification, the metallic liquids were eliminated ultimately by formation of refractory Ta 4 AlC 3 via reaction of Al, Ta and TaC. Reactions between the remnant Ta and TaC after Ta 4 AlC 3 formation resulted in ζ-Ta 4 C 3-z or h-Ta 2 C depending on the initial C:Ta ratio. The Ta 4 AlC 3 compound was compatible with the tantalum carbides. Microstructures of the TaC x -Al (x = 0.5–0.7) composites were consisted of ζ-Ta 4 C 3-z and Ta 4 AlC 3 fine lamellar grains to benefit the mechanical properties of the composites. The TaC 0.7 –20mol% Al composition had satisfying mechanical properties (flexural strength 613 ± 28 MPa and fracture toughness 11.2 ± 0.8 MPa m 1/2 ). TG-DSC evidenced an increase in oxidation resistance of the TaC x ceramics by the addition of 20 mol% Al.
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ENERGY CONVERSION AND MANAGEMENT
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2020
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IF 8.208
Rui Han,Jihui Gao,Siyu Wei,Fei Sun,Qingling Liu,Yukun Qin
Thermochemical energy storage based on the Calcium-Looping process characterized high energy density, low cost, and scalability, which is an advantageous candidate for the heat storage systems of Concentrated Solar Power plants. The main disadvantage of Calcium-Looping technology is the rapid decrease in the reactivity of CaO during cycling due to sintering. Many methods have been developed to synthesize high-cycling-behavior CaO-based materials. However, the state-of-the-art synthesized CaO-based materials remain far from the requirements due to the lack of consideration from an application perspective, which not only demands high-cycling-behavior but also needs to consider volumetric energy density. In this work, dense CaO/Al 2 O 3 composites were fabricated using the space-confined chemical vapor deposition method and considering both stability and volumetric energy density. Among different Ca-precursors, calcium formate does not expand during calcination, thus possesses a relatively dense structure, and taken together with the deposition of Al 2 O 3 on the surface of CaO grains obtained composites possessing high density and excellent stability. The optimized composite with 10 mol.% Al achieves a high volumetric energy density of 2.07 GJ/m 3 after 20 cycles, which is 1.58, 4.31, and 6.68 times of the capacity of limestone-derived CaO, sol–gel based CaO/Al 2 O 3 composites, and wet-mixing based CaO/Al 2 O 3 composites, respectively. This study presents a design principle for CaO-based heat storage materials, which are becoming denser and more stable.
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Nano Research
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2020
·Vol. 13
·期 2
·419-429
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IF 8.183
Chen Li-Li,Li Na,Shi Huifeng,Zhang Yuefei,Song Wei-Li,Jiao Shuqiang,Chen Haosen,Fang Daining
To achieve stable positive electrode for promoting the overall electrochemical performance of Al batteries (ABs), here novel cobalt boride (CoB) nanoclusters are synthesized to construct composite electrodes with few-layer graphene (FLG). Due to the presence of amorphous channels in the employed CoB nanoclusters, the ABs with FLG/CoB composite positive electrodes exhibit high rate capability and both mechanical and electrochemical stability in the ABs. With assistance of in situ scanning electron microscopy (SEM), the observation results suggest that the positive electrode of CoB nanoclusters holds almost ignorable volume variation upon electrochemical processes, which substantially alleviates the massive electrode expansion induced by the anion intercalation in the composite positive electrode. Interestingly, the composite positive electrodes provide stable reversible energy storage capability within a broadened temperature range (−30–60 °C), promising a novel strategy to design advanced ABs positive electrodes with enhanced overall energy storage performance.
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INDUSTRIAL & ENGINEERING CHEMISTRY RESEARCH
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2020
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IF 3.573
Yajie Chen,Siyuan Xia,Wei Ren,Zilong Zheng,Junhong Chen,Kefeng Ma,Chunpei Yu,Xinli Zhou,Wenchao Zhang
In this paper, sheet-like porous CuO (p-CuO), which was prepared using a hydrothermal-annealing method, has been first selected as an oxidizer to prepare n-Al/p-CuO/GO nanoenergetic composites. The n-Al/p-CuO/GO nanoenergetic materials were fabricated by means of vacuum-assisted self-assembly. Moreover, the effect from the quantity of added GO was studied on the morphology and reaction performance of the n-Al/p-CuO/GO nanoenergetic composites. The characterizations show that the resulting n-Al/p-CuO/GO composites have a uniform distribution of reaction components for an improved reactivity. The total heat release of the composite energetic material gradually rises up to 2306.7 J/g with the increasing GO content till 5 wt % but decreases as the GO content continues going up. Most importantly, the maximum value of the reaction exothermic heat is approximately 2.2 times higher in value than that of the as-prepared composite without GO addition. It is found out that the n-Al/p-CuO/GO nanothermite with 5 wt % GO can be successfully ignited by a semiconductor bridge at a 1 A current to produce a big and bright flame, thus indicating that its combustion performance is excellent. Therefore, the new nanoenergetic composites from a combination of GO and n-Al/p-CuO have a bright application prospect in the field of energetic materials.
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JOURNAL OF ALLOYS AND COMPOUNDS
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2019
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IF 4.175
Wei Sun,Ke Zhan,Zheng Yang,Rui Zhao,Tian Wang,Bin Zhao,Yan Ya,Junhe Yang
In recent years, graphene has attracted a lot of attention as a reinforcement to enhance aluminum (Al) matrix composites due to its two dimensional structure and excellent mechanical properties . However, there are still some obstacles that limit the performance of the composites, such as uniform distribution of graphene oxide (GO) and the interfacial bonding between GO and Al matrix. In this work, Cu 2+ ions acting as a bonding bridge were added into GO/Al powder suspension to improve the distribution of GO sheets on Al powder via a simple electrostatic adsorption method. Then, vacuum hot-pressing sintering was applied to fabricate bulk composites, and their mechanical properties were investigated. The results showed that doping 3 wt% Cu 2+ ions illustrated the best dispersion of GO on the surface of Al powder, meanwhile GO was maximally reduced. Compared with unreinforced Al, the hardness, compressive strength and flexural strength of the 3 wt% Cu-doped bulk composite were increased by 121%, 120% and 28%, respectively. However, the mechanical properties were deteriorated after doping 5 wt% Cu 2+ ions, due to the aggregation of GO on the surface of Al powder. This was attributed that Cu 2+ ions had a critical coagulation concentration in aqueous GO suspensions. It was expected this work could offer some useful information for preparing graphene reinforced metal composites.
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ELECTROCHIMICA ACTA
·
2023
·
IF 6.6
Chenjing Shi,Zijie Liu,Zhen Tian,Dan Li,Yanjun Chen,Li Guo,Yanzhong Wang
MXene nanosheets are one of the most promising supercapacitor electrode materials due to their excellent conductivity and redox activity. However, the balance of high capacity and rate performance of MXene nanosheets are still a big challenge due to their easy re-stacking, especially with a high mass loading. Here, the 3D MXene@graphene (MXene@rGO) hydrogel with high ion accessibility is engineered by Al-induced self-assembly of MXene and GO nanosheets. Trace acid solution is used as the initiator to etch the blunted aluminum oxide layer and release the Al 3+ ions, which acts as the linker to assemble nanosheets into 3D structure. At the same time, the mechanical strength of the hydrogel is further enhanced via the reduction of GO induced by Al. The MXene@rGO hydrogel exhibits a maximum area capacitance of 4.33 F cm −2 at 10 mA cm −2 and maintains a high area capacitance of 1.76 F cm −2 at 1000 mA cm −2 , indicating the high capacitance retention of 40.6%. Remarkably, the constructed asymmetric supercapacitor shows a high cyclic stability with a mere 8.37% decrease after 100,000 cycles, indicating the excellent application prospect.
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INDUSTRIAL & ENGINEERING CHEMISTRY RESEARCH
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2023
·
IF 4.2
Ning Ma,Xitao Wang,Xuemei Liu,Ningyan Li,Yuan Liu
Inhibiting the sintering of Cu-based catalysts for CO2 reverse water–gas shift (RWGS) reaction is still a great challenge. Herein, Cu–Al spinel supported on Al2O3 was prepared by a surface solid reaction and used as a precursor to obtain Cu particles with high dispersions and high stabilities. Due to the high dispersions of Cu cations in Cu–Al spinel, strong chemical interactions between Cu particles and newly generated Al2O3, and the isolation effects of Al2O3 particles, Cu particles derived from Cu–Al spinel exhibited smaller sizes after H2 reduction, excellent activities, and 300 h stabilities for RWGS reactions. However, Cu particles obtained from the supported CuO precursor showed much larger particle sizes (>70 nm) and inferior activities and stabilities for CO2 reverse water–gas shift reaction. This study made a successful attempt to enhance the activities and stabilities of Cu-based catalysts through changing the oxide precursor.
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JOURNAL OF SOLID STATE CHEMISTRY
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2023
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IF 3.3
Rui Zhao,Cheng Cheng,Xiurong Wu,Xueyan Bai,Fenghuan Wang
Due to the excellent pore structure , MOFs as the stationary phase was playing an important part in chromatography . In this work, the shell-core MIL-101(Al)@SiO 2 composites post-synthetic modified by ligands with different polarities were fabricated for separation of estrogens. The structure and morphology of these materials were characterized by X-ray diffraction (XRD), Fourier transform infrared spectrum (FTIR), scanning electron microscope (SEM) and Brunauer-Emmett-Teller (BET). In order to investigate the influence of the ligand polarity on chromatographic separation performance of estrogens, alkyl molecules with different chain length were introduced as the ligands. With the hydrophobicity and chain length of the ligands increasing, the resolutions of the MIL-101(Al)@SiO 2 columns for the separation of estrogens exhibited the tendency of a parabola. Best result was achieved on the C4-MIL-101(Al)@SiO 2 column. On that basis, the possible retention mechanism on C4-MIL-101(Al)@SiO 2 column was elucidated by studying the mobile phase effect on separation behavior.
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Frontiers of Chemical Science and Engineering
·
2020
·Vol. 15
·期 2
·269-278
·
IF 3.552
Hou Yuexin,Li Xiaoyun,Sun Minghui,Li Chaofan,Bakhtiar Syed ul Hasnain,Lei Kunhao,Yu Shen,Wang Zhao,Hu Zhiyi,Chen Lihua,Su Bao-Lian
Hierarchical single-crystal ZSM-5 zeolites with different Si/Al ratios (Hier-ZSM-5- x , where x = 50, 100, 150 and 200) were synthesized using an ordered mesoporous carbon-silica composite as hard template. Hier-ZSM-5- x exhibits improved mass transport properties, excellent mechanical and hydrothermal stability, and higher catalytic activity than commercial bulk zeolites in the benzyl alcohol self-etherification reaction. Results show that a decrease in the Si/Al ratio in hierarchical single-crystal ZSM-5 zeolites leads to a significant increase in the acidity and the density of micropores, which increases the final catalytic conversion. The effect of porous hierarchy on the diffusion of active sites and the final catalytic activity was also studied by comparing the catalytic conversion after selectively designed poisoned acid sites. These poisoned Hier-ZSM-5- x shows much higher catalytic conversion than the poisoned commercial ZSM-5 zeolite, which indicates that the numerous intracrystalline mesopores significantly reduce the diffusion path of the reactant, leading to the faster diffusion inside the zeolite to contact with the acid sites in the micropores predominating in ZSM-5 zeolites. This study can be extended to develop a series of hierarchical single-crystal zeolites with expected catalytic performance.
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APPLIED SURFACE SCIENCE
·
2023
·
IF 6.7
Xiaoqi Zhao,Yingxiao Li,Xue Zhang,Yanfang Gao,Ling Liu
Surface oxygen vacancy increases active site numbers, and multidimensional cross-linked structure improves the exposure of active sites. Thereby, they can enhance the oxygen reduction reaction (ORR) performance of Fe-N-C catalysts effectively. Herein, Fe(NO 3 ) 3 ·9H 2 O and carbon nanotubes (CNTs) were introduced into zeolitic imidazolate framework nano leaves (ZIF-L) to prepare multidimensional cross-linked Fe-N-CNTs with surface oxygen vacancies through co-pyrolysis at the high-temperature. As expected, the synthesized multidimensional cross-linked Fe-N-CNTs-900-0.2 composite rich in oxygen vacancies increased the conduction band potential and improved the reducing capacity. Thus, Fe-N-CNTs-900-0.2 possessed a better ORR electrochemical performance (half-wave potential = 0.892 V vs. RHE) that surpass the Pt/C catalysts. Moreover, the Al-air batteries containing Fe-N-CNTs-900-0.2 displayed a higher maximum power density than those of Pt/C catalysts. The electronic band structure shows that Fe-N-CNTs-900-0.2 rich in oxygen vacancy concentration has higher conduction band potential and effectively improves the activity of ORR catalysts. This work innovatively proposes that the joint work of multidimensional cross-linked structure and oxygen defects is an effective method to enhance the ORR performance and clarifies its internal reaction mechanism, which provides a new idea to design and preparer Fe-N-C catalysts.
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JOURNAL OF POWER SOURCES
·
2023
·
IF 9.2
Xuyang Wang,Huihui Luo,Tao Liu,Lili Zhang,Zigeng Liu,Luxia Bu,Wei Wang
As a high-power battery system, Al-air batteries exhibit a wide range of potential applications. However, Al-air batteries are susceptible to significant open-circuit corrosion of the aluminum electrodes when removed from the electrolyte during standby, resulting in the formation of a dense film of corrosion products on the aluminum electrode surface . This, in turn, impedes the re-discharge performance of Al-air batteries. Based on an electrode/electrolyte interface adjustment strategy, mannitol is used as the additive to be added into 4 M KOH solution to improve re-discharge performance. Experimental analyses and theoretical calculations reveal that the inclusion of mannitol enhances the re-discharge performance of Al-air batteries through a combination of hydrogen bonding and adsorption. Importantly, it is noted that mannitol has minimal impact on the battery power density. The reason for the improvement is explained reasonably by a proposed mechanism. These findings offer valuable insights for the development of Al-air batteries with high performance.
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SEPARATION AND PURIFICATION TECHNOLOGY
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2023
·
IF 8.6
Yi Ren,Naiwen Li,Jun Li,Weiming Zhang,Chao Liu,Bo Lai
Iron based Fenton-like processes have been widely investigated, while how to regulate active species generation still is a problem of concern. In this study, MILs(Al) with various carboxyl group amounts were used as research tools, loading iron for Fenton-like oxidation, to investigate the effect of free carboxyl group on surface or free HO generation. Active species identification indicates that surface and free HO were main active species for carbamazepine removal. Moreover, it was concluded that contribution of free HO for the decontamination was positively correlated with carboxyl group amounts on MILs(Al). With free carboxyl group amounts increasing from 3.07 to 5.09 mmol/g on MILs(Al)-Fe, concentration of free HO for carbamazepine removal increased from 47.4% to 62.5%. The mechanisms of carboxyl group amounts impact the chemical state of HO was proposed as steric hindrance effect and charge density near iron sites. The destruction of carbamazepine was proposed in different systems by intermediates determination, and the results indicate that the existing form of HO mainly influenced the efficiency of pollutant degradation, rather than oxidation mechanisms of it. Various pollutants degradation in different MILs(Al)-Fe catalyzed Fenton-like systems were investigated as well, to understand the superiority of different HO for decontamination. MILs(Al)-Fe with various carboxyl group amounts catalyzed Fenton-like processes could remove 34.2%–73.0% carbamazepine, 56.7%–93.8% sulfamethoxazole, 36.4%–75.6% bisphenol S and 43.8–79.7% salicylic acid. This study understood the regulation of active species by carboxyl group in MILs(Al)-Fe/H 2 O 2 systems, and sheds new light on active species precise regulation in Fenton-like systems.
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