CERAMICS INTERNATIONAL
·
2025
·
IF 5.6
Wentao Huai,Xinyu Fu,Yifan Zhao,Zhenhao Cai,Saiwei Luan,Zhouyi Xu,Huizhan He,Jingxi Wang,Zhenxiao Fu,Xiuhua Cao,Lei Zhang,Rong Sun
Multilayer ceramic capacitors (MLCCs) are used in harsh environments such as automotive electronics, which require high reliability and temperature stability. Therefore, the regulation of Ho/Mg co-doping on the core-shell structure of BaTiO 3 -based MLCCs and the effect on temperature stability and reliability were investigated in this study. Ceramics and MLCCs device with various Ho/Mg molar ratios (1.2–1.8) were prepared using the solid-state reaction method. The study revealed the synergistic effects of Ho/Mg doping on shell concentration, shell thickness, and oxygen vacancy inhibition. The results showed that with the Ho/Mg molar ratio increase, the shell thickness increased from 27.98% to 62.24%. The temperature coefficient of capacitance (TCC) for the sample with Ho/Mg=1.8 satisfied the EIA-X7S (ΔC/C 25°C = ±22%, –55 °C to 125 °C) specification. X-ray photoelectron spectroscopy confirmed that Ho 3+ effectively captured oxygen vacancies by forming defect dipoles, while impedance spectroscopy demonstrated that the shell significantly inhibited carrier migration. Furthermore, the MLCCs device with Ho/Mg=1.8 exhibited a breakdown strength of 96.38 kV/mm and met the more stringent EIA-X7R (ΔC/C 25°C = ±15%, –55 °C to 125 °C) specification. These findings indicate that Ho/Mg co-doping effectively optimizes the core-shell structure, offering valuable theoretical guidance for developing MLCCs with enhanced temperature stability and reliability.
研究领域:
电子材料
·
功能陶瓷
·
介电物理
·
材料科学
·
无机非金属材料
·
器件可靠性
·
固态化学
✓ 已验证
产品关联
DOI
高影响因子
Nanomaterials
·
2024
·Vol. 14
·期 15
·1240
·
IF 4.4
Dongmei Zhang,Jiaqi Zhao,Yangyang Peng,Yuchao Li,Wenbin Guo,Chengzhu Liao
Water pollution seriously affects the development of society and human life. There are various kinds of pollutants, including soluble pollutants and insoluble floaters on the water surface. Herein, the photocatalyst semiconductor BiOCl and superhydrophobic functional particles Mg(OH)2were deposited on the surfaces of canvas and polyester felt to construct superhydrophobic canvas and polyester felt. The contact angles of the synthetic superhydrophobic canvas and polyester felt were measured as 152° and 155.3°, respectively. The selective adsorption of hexadecane was achieved using the wetting difference between the surface of water and pollutants floating on the surface. For dissolved pollutants, the surface wettability needed to be changed with the help of ethanol. The degradation efficiencies were all greater than 90%, demonstrating the versatility of the synthetic superhydrophobic canvas and polyester felt.
研究领域:
环境科学
·
材料科学
·
污染控制
·
纳米技术
✓ 已验证
产品关联
DOI
PubMed
高影响因子
JOURNAL OF THE ENERGY INSTITUTE
·
2022
·
IF 6.47
Kai Shi,Xia An,Yali Du,Zhaoyang Fan,Xu Wu,Xianmei Xie
A series of nickel catalysts supported on Al 2 O 3 that modified with Ce-, Zr-, and Mg-promoter were prepared via a sol-gel method and a subsequent impregnation method for the ethanol steam reforming reaction (ESR). The effect of promoters on the carbon deposition was focused. Compared with Ni/Al 2 O 3 catalyst, the introduction of different promoters decreased the selectivity for CH 2 CH 2 to different extent, especially, Ce-, Mg- containing catalysts completely suppressed the production of CH 2 CH 2 for 30 h tested at 500 °C. And the medium and strong acid sites were confirmed as the major sites for CH 2 CH 2 production. Encapsulation carbon derived from ethylene takes the primary responsibility for carbon deposition, and the formation of metal carbide is the other reason for causing carbon deposition. Among the tested catalysts, Ni/Mg–Al 2 O 3 exhibited a better performance for anti-carbon, which was attributed to the blockage of medium and strong acid sites as well as the high Ni crystallinity .
研究领域:
催化
·
化学工程
·
材料科学
✓ 已验证
产品关联
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
·
化工
·
材料科学
✓ 已验证
DOI
高影响因子
POLYMER
·
2022
·
IF 4.432
Qisong Lin,Feng Gao,Yongjun Wang,Wangyang Lu,Wenxing Chen
Antimony-free poly(ethylene terephthalate) (PET) has been synthesized through polycondensation of p -phthalic acid and ethylene glycol , and then subjected to a viscosity-increasing process by liquid-state polycondensation (LSP). For both of these processes, a novel environmentally benign ethylene glycol-soluble Ti/Mg bimetal (TM) catalyst has been used. The structure of the TM catalyst has been comprehensively characterized and its catalytic activity in the polycondensation reaction has been evaluated and compared with those of other titanium-based catalysts. The results reveal that the TM catalyst is a chelated complex with high catalytic activity for polycondensation to afford PET without significant side reactions. Indeed, the LSP process catalyzed by TM affords a PET product with high intrinsic viscosity suitable for industrial yarn production (1.08 dL/g) within 60 min, and that exhibits higher thermostability with increasing intrinsic viscosity. Finally, the kinetics of the TM-catalyzed polycondensation has been probed based on the variation of intrinsic viscosity with increasing polycondensation time.
研究领域:
材料科学
·
聚合物化学
·
催化
·
环境科学
✓ 已验证
产品关联
DOI
高影响因子
Frontiers of Chemical Science and Engineering
·
2024
·Vol. 18
·期 4
·1-15
·
IF 4.3
Guo Yunyu,Wang Yiran,Shao Yuewen,Zhang Shu,Wang Yi,Hu Song,Xiang Jun,Hu Xun
During steam reforming, the performance of a catalyst and amount/property of coke are closely related to reaction intermediates reaching surface of a catalyst. Herein, modification of reaction intermediates by placing Mg-Al-hydrotalcite above Ni/KIT-6 catalyst in steam reforming of glycerol was conducted at 300 to 600 °C. The results revealed that the catalytic activity of Ni/KIT-6 in the lower bed was enhanced with either Mg 1 -Al 5 -hydrotalcite (containing more acidic sites) or Mg 5 -Al 1 -hydrotalcite (containing more alkaline sites) as upper-layer catalyst. The in situ infrared characterization of steam reforming demonstrated that Mg-Al-hydrotalcite catalyzed the deoxygenation of glycerol, facilitating the reforming of the partially deoxygenated intermediates over Ni/KIT-6. Mg-Al-hydrotalcite as protective catalyst, however, did not protect the Ni/KIT-6 from formation of more coke. Nonetheless, this did not lead to further deactivation of Ni/KIT-6 while Mg 5 -Al 1 -hydrotalcite even substantially enhanced the catalytic stability, even though the coke was much more significant than that in the use of single Ni/KIT-6 (52.7% vs. 28.6%). The reason beneath this was change of the property of coke from more aliphatic to more aromatic. Mg 5 -Al 1 -hydrotalcite catalyzed dehydration of glycerol, producing dominantly reaction intermediates bearing C=C, which formed the catalytic coke of with carbon nanotube as the main form with smooth outer walls as well as higher aromaticity, C/H ratio, crystallinity, crystal carbon size, thermal stability, and resistivity toward oxidation on Ni/KIT-6 in the lower bed. In comparison, the abundance of acidic sites on Mg 1 -Al 5 -hydrotalcite catalyzed the formation of more oxygen-containing species, leading to the formation of carbon nanotubes of rough surface on Ni/KIT-6.
研究领域:
催化
·
化学工程
·
材料科学
·
能量转换
·
表面化学
✓ 已验证
DOI
高影响因子
FUEL PROCESSING TECHNOLOGY
·
2022
·
IF 8.129
Jida Wang,Feng Shi,Can Liu,Yi Lu,Xu Lin,Defa Hou,Jirong Li,Dechao Wang,Zhifeng Zheng,Yunwu Zheng
In this study, a series of cost-effective and eco-friendly Ca-Mg-Al and Ni-modified Ca-Mg-Al catalysts were successfully synthesized with different methods (coprecipitation, impregnation and mechanical mixing method) and applied to catalytic pyrolysis vapor upgrading of oleic acid (OA) to produce gasoline-kerosene rich production using methanol as a hydrogen donor . In addition, the effects of the process parameters (catalyst type, OA to methanol ratio, pyrolysis/catalytic temperature, catalyst loading, feedstock injection volume) on the product yield and selectivity were explored, and the reuse properties and deactivation mechanism were also evaluated. Active Ni species coupled with methanol were more conducive to enhancing the catalyst activity and OA conversion and obviously increased the selectivity toward the gasoline-kerosene product. The impregnation method was favorable for the formation of NiAl 2 O 4 species, and coprecipitation method suppressed the formation of NiAl 2 O 4 species. The enhanced activity and deoxygenation selectivity of the coprecipitation method (NiCaMgAl) at lower pyrolysis temperatures was attributed to the abundant higher specific surface area and pore size, higher active metal oxide (Ni 2+ ) and well-active Ni dispersion with a smaller particle size, as well as the lower acidity and partially oxidized Ni, which suppressed the NiAl 2 O 4 spinel phase formation compared with the Ni/Ca-Mg/Al (impregnation) and Ca-Mg-Al (mixing) catalysts, which was beneficial to the decarbonylation/ decarboxylation reaction and inhibited the hydrocracking reaction of C C. Therefore, 100% conversion, 97.12% hydrocarbon yield, 54.53% gasoline and 58.80% kerosene content over NiCaMgAl catalyst were obtained under optimal conditions (pyrolysis/catalytic temperature = 450/500°C, catalyst loading = 1.5 g, feedstock injection volume = 0.1 ml/min and OA to methanol ratio = 3:1). Moreover, NiCaMgAl catalyst also demonstrated good reusability and hydrothermal stability performance due to the lower amount of coke deposition with a lower graphitized structure, which suppressed sintering.
研究领域:
化学工程
·
催化剂科学
✓ 已验证
产品关联
DOI
高影响因子
JOURNAL OF MATERIALS SCIENCE & TECHNOLOGY
·
2024
·
IF 11.2
Haoyuan Zheng,Yuxiao Jia,Chen Jin,Hang Che,Chia-TseLee,Guang Liu,Li Wang,Yuyuan Zhao,Shixuan He,Haizhen Liu,Xinhua Wang,Yifeng Yu,Mi Yan
The magnesium based metal hydrogen storage composite system Mg(NH 2 ) 2 -2LiH has a theoretical hydrogen storage capacity of 5.6 wt.% and is a promising hydrogen storage material for vehicles. However, its application is limited due to serious thermodynamic and kinetic barriers. Introducing efficient catalysts is an effective method to improve the hydrogen storage performance of Mg(NH 2 ) 2 -2LiH. This article investigates for the first time the use of nano rare earth oxide CeO 2 (∼44.5 nm) as an efficient modifier, achieving comprehensive regulation of the hydrogen storage performance of Mg(NH 2 ) 2 -2LiH composite system through oxygen vacancy driven catalysis. The modification mechanism of nano CeO 2 is also systematically studied using density functional theory (DFT) calculations and experimental results. Research has shown that the comprehensive hydrogen storage performance of the Mg(NH 2 ) 2 -2LiH-5 wt.% CeO 2 composite system is optimal, with high hydrogen absorption and desorption kinetics and reversible performance. The initial hydrogen absorption and desorption temperatures of the composite system were significantly reduced from 110/130°C to 65/80°C, and the release of by-product ammonia was significantly inhibited. Under the conditions of 170°C/50 min and 180°C/100 min, 4.37 wt.% of hydrogen can be rapidly absorbed and released. After 10 cycles of hydrogen release, the hydrogen cycle retention rate increased from 85% to nearly 100%. Further mechanistic studies have shown that the nano CeO 2− x generated in situ during hydrogen evolution can effectively weaken the Mg–N and N–H bonds of Mg(NH 2 ) 2 , exhibiting good catalytic effects. Meanwhile, oxygen vacancies provide a fast pathway for the diffusion of hydrogen atoms in the composite system. In addition, nano CeO 2− x can effectively inhibit the polycrystalline transformation of the hydrogen evolving product Li 2 MgN 2 H 2 in the system at high temperatures, reducing the difficulty of re-hydrogenation of the system. This study provides an innovative perspective for the efficient modification of magnesium based metal hydrogen storage composite materials using rare earth based catalysts, and also provides a reference for regulating the comprehensive hydrogen storage performance of hydrogen storage materials using rare earth catalysts with oxygen vacancies.
研究领域:
材料科学
·
催化
·
氢气存储
·
纳米技术
✓ 已验证
DOI
高影响因子
ACS Applied Nano Materials
·
2022
·
IF 6.14
Lijing Zhang,Jiaqi Han,Yuchao Wang,Wenbo Yang,Shengyang Tao
Achieving a room-temperature Suzuki–Miyaura coupling (SMC) with high efficiency is of great significance to the development of low-carbon organic synthesis. Nevertheless, it is still a great challenge to construct a promising nanocatalyst with high activity for room-temperature SMC reaction. In this paper, a strong alkaline-supported nanocatalyst Pd/Mg(OH)2/MgO–ZrO2 was rationally developed based on MgO–ZrO2 hybrid nanofibers. Physicochemical characterizations present that the in situ conversion of MgO to Mg(OH)2 on the surface of the nanofibers results in a great increase in surface alkalinity of the carrier. The strong alkalinity can greatly accelerate the oxidation addition and transmetalation of the SMC process, resulting in the obvious reduction of activation energy of the reaction (Ea = 9.0 kJmol–1 for Ph–Br). The coupling conversion can reach up to 100% at room temperature within 8 min with a maximum TOF > 6516 h–1. It also shows an excellent performance in substrate applicability and chlorobenzene activation. The rational design of a high-basicity catalyst for room-temperature SMC will be a rewarding attempt for the development of low-carbon green organic synthesis.
研究领域:
催化化学
·
有机合成
·
纳米材料科学
✓ 已验证
产品关联
DOI
高影响因子
JOURNAL OF RARE EARTHS
·
2024
·
IF 5.2
Haoyuan Zheng,Yuxiao Jia,Chen Jin,Hang Che,Chia-Tse Lee,Zhenke Chen,Guang Liu,Li Wang,Shixuan He,Xinhua Wang,Haizhen Liu,Mi Yan
The Mg(NH 2 ) 2 -2LiH composite system is a promising vehicle-mounted hydrogen storage material, but its application is limited due to serious thermodynamic and kinetic barriers. Adding additives can effectively optimize their hydrogen absorption and desorption kinetics and thermodynamic performance. In this work the comprehensive hydrogen storage performance of Mg(NH 2 ) 2 -2LiH with extremely small nano rare earth borides is improved, and a series of characterization methods and density functional theory (DFT) calculation systems was combined to study its hydrogen storage improvement mechanism. The research results show that the method of adding 5 wt% molten salt to prepare nano CeB 6 (24.5 nm) can significantly reduce the initial hydrogen absorption/release temperature of Mg(NH 2 ) 2 -2LiH from 110/130 to 45/90 °C, inhibit the generation of ammonia by-products, and improve hydrogen purity. Under low-temperature hydrogen absorption conditions at 120 °C, the improved sample can absorb 2.81 wt% hydrogen gas, with a hydrogen absorption capacity more than 3.5 times of the unmodified sample. The amount of hydrogen released at 150 °C reaches 3.35 wt%, which is more than twice that of the pristine sample, demonstrating excellent hydrogen absorption and release kinetics performance. After 10 consecutive hydrogen cycles, 4.64 wt% hydrogen can still be released, and the cycle retention rate can be increased from 85% before improvement to nearly 100%, demonstrating good reversibility. Mechanism studies show that nano CeB 6 can effectively weaken the Mg–N and N–H bonds of Mg(NH 2 ) 2 and inhibit the polycrystalline transformation of the hydrogen evolution product Li 2 MgN 2 H 2 at high temperatures. It can also provide nucleation active sites for hydrogen absorption and desorption in the material, making the system possess superior hydrogen absorption and desorption performance and cycling stability. This study provides new insights into the role of rare earth borides in Mg(NH 2 ) 2 -2LiH hydrogen storage materials, both experimentally and theoretically.
研究领域:
材料科学
·
化学工程
·
物理化学
·
理论化学
✓ 已验证
DOI
高影响因子
CHEMICAL ENGINEERING JOURNAL
·
2023
·
IF 15.1
Haonan Ma,Chi Zhang,Long Chen,Mengning Xi,Zhiqiang Wang,Zheng Ni,Kecheng Zhu,Hanzhong Jia
Sorption processes at the mineral–water interface are of great importance in dominating the fate and availability of metalloid contaminants in natural environment. Aiming at a thorough understanding of the complexation of antimony (Sb) on metal hydroxide, we conducted first-principles molecular dynamic (FPMD) simulations and batch adsorption experiments to elucidate the quantitative mechanism of Sb complexation on Mg(OH) 2 . Batch experiments showed the sorption of Sb(III) is nearly pH-independent, while increasing pH markedly weakened Sb(V) sorption; the measured sorption isotherm curves were well fitted by Langmuir model. Subsequently, molecular-level mechanism of Sb(V)/Sb(III) on brucite basal and edge surfaces were revealed by FPMD, including microscopic surface reactive sites, local complexing structures and coordination geometries, and complexing free energies. Results showed that Sb(III)/Sb(V) can form outer-sphere complexation on basal surface by hydrogen bonding. On edge surface, Sb(III)/Sb(V) formed stable inner-sphere mononuclear monodentate and binuclear bidentate complexes. The calculated free energies indicated that the binuclear bidentate complexing was more favorable than monodentate structure, and the complexation of Sb(III) was more stable than Sb(V). Accordingly, reaction pathway of the ligand exchange and thermodynamic stability of the different inner-sphere complexes were clarified. This study provides theoretical basis for evaluating the environmental risk of Sb and improving the engineering efficiency of Sb-contaminated water management.
研究领域:
环境科学
·
化学
·
材料科学
✓ 已验证
产品关联
DOI
高影响因子
CHEMICAL ENGINEERING JOURNAL
·
2021
·
IF 13.273
Rui Ma,Xueqian Yan,Xiaohui Mi,Yaoguo Wu,Jin Qian,Qiuyu Zhang,Guang-Hao Chen
In this study, the Mg-Fe-LDH@biochar composite was firstly fabricated and applied for effectively activation peroxymonosulfate (PMS) for aqueous doxycycline (DOX) degradation. The physiochemical properties of the as-synthesized composite were thoroughly characterized. In the developed Mg-Fe-LDH@biochar/PMS system, the catalytic DOX degradations were evaluated under different conditions. Under the optimal condition (0.75 g/L catalyst loading, 0.75 g/L PMS dosage, pH = 7.0), about 88.76% DOX (35 mg/L) was removed within 120 mins. The results of quenching test and electron paramagnetic resonance (EPR) illustrated that the •OH, SO 4 • - and •O 2 – radicals all contributed to the DOX degradation in the Mg-Fe-LDH@biochar/PMS system, whereas the 1 O 2 -based non-radical degradation played the dominant role in DOX removal. The developed system was almost not adversely affected by the high-strength anions and exhibited high DOX decomposition rates in a wide pH range from 3.0 to 9.0, indicating the great potential in the practical application. The satisfactory reusability of the composite catalyst was demonstrated in the recycling test, with the DOX removal efficiency slightly declined from 90.08 to 84.42% after five runs. Based on the generation of reactive oxidative species and the transformation intermediates identified by HPLC-MS, the possible degradation pathways and reaction mechanism of DOX degradation in Mg-Fe-LDH@biochar/PMS system were proposed.
研究领域:
环境科学
·
化学工程
·
水处理
·
材料科学
✓ 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）