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Li₄SiO₄-coated LiNi_0.5Mn_1.5O₄ as the high performance

Shifeng YANG, Wenfeng REN, Jian CHEN

《能源前沿（英文）》 2017年第11卷第3期页码 374-382 doi: 10.1007/s11708-017-0494-2

摘要： The preparation of Li SiO -coated LiNi Mn O materials by sintering the SiO -coated nickel-manganese oxides with lithium salts using abundant and low-cost sodium silicate as the silicon source was reported. The samples were characterized by X-ray diffraction, scanning electron microscopy and transmission electron microscopy. It was found that a uniform and complete SiO coating layer could be obtained at a suitable pH value of 10, which transformed to a good Li SiO coating layer afterwards. When used as the cathode materials for lithium-ion batteries, the Li SiO -coated LiNi Mn O samples deliver a better electrochemical performance in terms of the discharge capacity, rate capability, and cycling stability than that of the pristine material. It can still deliver 111.1 mAh/g at 20 C after 300 cycles, with a retention ratio of 93.1% of the stable capacity, which is far beyond that of the pristine material (101.3 mAh/g, 85.6%).

关键词： lithium-ion batteries cathode material LiNi_0.5Mn_1.5O₄ lithium-ion conductor coating

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Effects of gradient concentration on the microstructure and electrochemical performance of LiNi

Wenming Li, Weijian Tang, Maoqin Qiu, Qiuge Zhang, Muhammad Irfan, Zeheng Yang, Weixin Zhang

《化学科学与工程前沿（英文）》 2020年第14卷第6期页码 988-996 doi: 10.1007/s11705-020-1918-9

摘要： Nickel(Ni)-rich layered materials have attracted considerable interests as promising cathode materials for lithium ion batteries (LIBs) owing to their higher capacities and lower cost. Nevertheless, Mn-rich cathode materials usually suffer from poor cyclability caused by the unavoidable side-reactions between Ni ions on the surface and electrolytes. The design of gradient concentration (GC) particles with Ni-rich inside and Mn-rich outside is proved to be an efficient way to address the issue. Herein, a series of LiNi Co Mn O (LNCM622) materials with different GCs (the atomic ratio of Ni/Mn decreasing from the core to the outer layer) have been successfully synthesized via rationally designed co-precipitation process. Experimental results demonstrate that the GC of LNCM622 materials plays an important role in their microstructure and electrochemical properties. The as-prepared GC3.5 cathode material with optimal GC can provide a shorter pathway for lithium-ion diffusion and stabilize the near-surface region, and finally achieve excellent electrochemical performances, delivering a discharge capacity over 176 mAh·g at 0.2 C rate and exhibiting capacity retention up to 94% after 100 cycles at 1 C. The rationally-designed co-precipitation process for fabricating the Ni-rich layered cathode materials with gradient composition lays a solid foundation for the preparation of high-performance cathode materials for LIBs.

关键词： gradient concentration Ni-rich LiNi_0.6Co_0.2-Mn_0.2O₂ electrochemical performance lithium-ion battery

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CO₂ methanation and co-methanation of CO and CO₂ over Mn-promoted Ni/Al₂O₃ catalysts

Kechao Zhao,Zhenhua Li,Li Bian

《化学科学与工程前沿（英文）》 2016年第10卷第2期页码 273-280 doi: 10.1007/s11705-016-1563-5

摘要： A series of Mn-promoted 15 wt-% Ni/Al O catalysts were prepared by an incipient wetness impregnation method. The effect of the Mn content on the activity of the Ni/Al O catalysts for CO methanation and the co-methanation of CO and CO in a fixed-bed reactor was investigated. The catalysts were characterized by N physisorption, hydrogen temperature-programmed reduction and desorption, carbon dioxide temperature-programmed desorption, X-ray diffraction and high-resolution transmission electron microscopy. The presence of Mn increased the number of CO adsorption sites and inhibited Ni particle agglomeration due to improved Ni dispersion and weakened interactions between the nickel species and the support. The Mn-promoted 15 wt-% Ni/Al O catalysts had improved CO methanation activity especially at low temperatures (250 to 400 °C). The Mn content was varied from 0.86% to 2.54% and the best CO conversion was achieved with the 1.71Mn-Ni/Al O catalyst. The co-methanation tests on the 1.71Mn-Ni/Al O catalyst indicated that adding Mn markedly enhanced the CO methanation activity especially at low temperatures but it had little influence on the CO methanation performance. CO methanation was more sensitive to the reaction temperature and the space velocity than the CO methanation in the co-methanation process.

关键词： Mn promotion nickel catalysts CO₂ methanation co-methanation of CO and CO₂

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Large-scale synthesis of isolated Mn2O3 nanotube/fiber with ferric nitrate as catalyst

ZHANG Aifei, LIU Jiping, L? Guangshu

《化学科学与工程前沿（英文）》 2007年第1卷第1期页码 55-58 doi: 10.1007/s11705-007-0011-y

摘要： Isolated MnO nanotubes and nanofibers were prepared very easily at a large scale with the liquid-phase catalysis method. The MnO nanotubes had dimensions of 30 50 nm (exterior diameter) and 0.2 1.0 ?m (length), approximately. The O nanofibers had dimensions of 10 30 nm (diameter) and 0.4 2.0 ?m (length), approximately. Nano-O with different microstructures including nanotubes, nanofibers and nanoparticles could be selectively synthesized by controlling the contents and proportions of potassium permanganate and ferric nitrate. Ferric nitrate was an ideal catalyst for the preparation of O nanotube/fiber. When cobalt nitrate or nickel nitrate was used as catalyst, only amorphous nano-O was synthesized. X-ray diffraction (XRD) result shows that the O nanotube has a crystalline structure different from o-O, t-O, h-O and ?-O.

关键词： different nickel exterior diameter nanotube XRD

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Construction of nitrogen-doped carbon cladding LiMnO film electrode with enhanced stability for electrochemically selective extraction of lithium ions

《化学科学与工程前沿（英文）》 2023年第17卷第12期页码 2050-2060 doi: 10.1007/s11705-023-2343-7

摘要： Reducing the dissolution of Mn from LiMn₂O₄ (LMO) and enhancing the stability of film electrodes are critical and challenging for Li⁺ ions selective extraction via electrochemically switched ion exchange technology. In this work, we prepared a nitrogen-doped carbon cladding LMO (C-N@LMO) by polymerization of polypyrrole and high-temperature annealing in the N₂ gas to achieve the above purpose. The modified C-N@LMO film electrode exhibited lower Mn dissolution and better cyclic stability than the LMO film electrode. The dissolution ratio of Mn from the C-N@LMO film electrode decreased by 42% compared to the LMO film electrode after 10 cycles. The cladding layer not only acted as a protective layer but also functioned as a conductive shell, accelerating the migration rate of Li⁺ ions. The intercalation equilibrium time of the C-N@LMO film electrode reached within an hour during the extraction of Li⁺ ions, which was 33% less compared to the pure LMO film electrode. Meanwhile, the C-N@LMO film electrode retained evident selectivity toward Li⁺ ions, and the separation factor was 118.38 for Li⁺ toward Mg²⁺ in simulated brine. Therefore, the C-N@LMO film electrode would be a promising candidate for the recovery of Li⁺ ions from salt lakes.

关键词： LiMn₂O₄ lithium extraction surface coating cyclic stability Mn dissolution

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Rh₂O₃/hexagonal CePO₄ nanocatalysts for N₂O decomposition

Huan Liu, Zhen Ma

《化学科学与工程前沿（英文）》 2017年第11卷第4期页码 586-593 doi: 10.1007/s11705-017-1659-6

摘要： Hexagonal CePO nanorods were prepared by a precipitation method and hexagonal CePO nanowires were prepared by hydrothermal synthesis at 150 °C. Rh(NO ) was then used as a precursor for the impregnation of Rh O onto these CePO materials. The Rh O supported on the CePO nanowires was much more active for the catalytic decomposition of N O than the Rh O supported on CePO nanorods. The stability of both catalysts as a function of time on stream was studied and the influence of the co-feed (CO , O , H O or O /H O) on the N O decomposition was also investigated. The samples were characterized by N adsorption-desorption, inductively coupled plasma optical emission spectroscopy, X-ray diffraction, transmission electron microscopy, X-ray photoelectron microscopy, hydrogen temperature-programmed reduction, oxygen temperature-programmed desorption, and CO temperature-programmed desorption in order to correlate the physicochemical and catalytic properties.

关键词： Rh₂O₃ CePO₄ N₂O decomposition

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ZnFe₂O₄/BiVO₄ Z-scheme heterojunction for efficient visible-light photocatalytic

《化学科学与工程前沿（英文）》 2023年第17卷第11期页码 1728-1740 doi: 10.1007/s11705-023-2322-z

摘要： A novel Z-scheme ZnFe₂O₄/BiVO₄ heterojunction photocatalyst was successfully synthesized using a convenient solvothermal method and applied in the visible light photocatalytic degradation of ciprofloxacin, which is a typical antibiotic contaminant in wastewater. The heterostructure of as-synthesized catalysts was confirmed using X-ray diffraction, scanning electron microscopy, transmission electron microscopy and X-ray photoelectron spectroscopy characterizations. Compared with the single-phase counterparts, ZnFe₂O₄/BiVO₄ demonstrated considerably enhanced photogenerated charge separation efficiencies because of the Z-scheme transfer mechanism of electrons between the composite photocatalysts. Consequently, the 30% ZnFe₂O₄/BiVO₄ catalyst afforded a degradation rate of up to 97% of 20 mg/L ciprofloxacin under 30 min of visible light irradiation with a total organic carbon removal rate of 50%, which is an excellent activity compared with ever reported BiVO₄-based catalysts. In addition, the liquid chromatography-mass spectrometry and quantitative structure-activity relationships model analyses demonstrated that the toxicity of the intermediates was lower than that of the parent ciprofloxacin. Moreover, the as-synthesized ZnFe₂O₄/BiVO₄ heterojunctions were quite stable and could be reused at least four times. This study thus provides a promising Z-scheme heterojunction photocatalyst for the efficient removal and detoxication of antibiotic pollutants from wastewater.

关键词： ZnFe₂O₄/BiVO₄ Z-scheme heterojunction photocatalytic degradation ciprofloxacin

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NiCo2O4@quinone-rich N–C core–shell nanowires as composite electrode for electric double layer capacitor

《化学科学与工程前沿（英文）》 2023年第17卷第4期页码 373-386 doi: 10.1007/s11705-022-2223-6

摘要： The bind-free carbon cloth-supported electrodes hold the promises for high-performance electrochemical capacitors with high specific capacitance and good cyclic stability. Considering the close connection between their performance and the amount of carbon material loaded on the electrodes, in this work, NiCo₂O₄ nanowires were firstly grown on the substrate of active carbon cloth to provide the necessary surface area in the longitudinal direction. Then, the quinone-rich nitrogen-doped carbon shell structure was formed around NiCo₂O₄ nanowires, and the obtained composite was used as electrode for electric double layer capacitor. The results showed that the composite electrode displayed an area-specific capacitance of 1794 mF∙cm^–2 at the current density of 1 mA∙cm^–2. The assembled symmetric electric double layer capacitor achieved a high energy density of 6.55 mW∙h∙cm^–3 at a power density of 180 mW∙cm^–3. The assembled symmetric capacitor exhibited a capacitance retention of 88.96% after 10000 charge/discharge cycles at the current density of 20 mA∙cm^–2. These results indicated the potentials in the preparation of the carbon electrode materials with high energy density and good cycling stability.

关键词： carbon cloth NiCo₂O₄ nanowires core−shell structure quinone-rich electric double layer capacitor

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Pd/Fe3O4 supported on bio-waste derived cellulosic-carbon as a nanocatalyst for C–C coupling and electrocatalytic

《化学科学与工程前沿（英文）》 2022年第16卷第10期页码 1514-1525 doi: 10.1007/s11705-022-2158-y

摘要： The current work describes the synthesis of a new bio-waste derived cellulosic-carbon supported-palladium nanoparticles enriched magnetic nanocatalyst (Pd/Fe₃O₄@C) using a simple multi-step process under aerobic conditions. Under mild reaction conditions, the Pd/Fe₃O₄@C magnetic nanocatalyst demonstrated excellent catalytic activity in the Hiyama cross-coupling reaction for a variety of substrates. Also, the Pd/Fe₃O₄@C magnetic nanocatalyst exhibited excellent catalytic activity up to five recycles without significant catalytic activity loss in the Hiyama cross-coupling reaction. Also, we explored the use of Pd/Fe₃O₄@C magnetic nanocatalyst as an electrocatalyst for hydrogen evolution reaction. Interestingly, the Pd/Fe₃O₄@C magnetic nanocatalyst exhibited better electrochemical activity compared to bare carbon and magnetite (Fe₃O₄ nanoparticles) with an overpotential of 293 mV at a current density of 10 mA·cm^–2.

关键词： bio-waste cellulosic-carbon Pd/Fe₃O₄ Hiyama cross-coupling hydrogen evolution reaction recyclability

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Preparation and property characterization of PAA/Fe3O4 nanocomposite

WEI Shanshan, ZHANG Yi, XU Jiarui

《化学科学与工程前沿（英文）》 2007年第1卷第3期页码 233-237 doi: 10.1007/s11705-007-0042-4

摘要： PAA/FeO nanocomposites were prepared by mixing nano-FeOvent. The materials were characterized by transmission electron microscope (TEM), Fourier transform infrared spectroscope (FTIR), thermogravimetry analysis (TGA), dynamic ultra-micro hardness tester (DUMHT) and superconducting quantum interference device (SQUID) magnetometer. Results showed that PAA coordinated with nano-FeO to form a cross-linking structure. The presence of nano-FeO enhanced the thermal stability of the nanocomposite. The elasticity and hardness of the nanocomposite increased, and the indentation depth reduced with the increase of FeO content in the composites. The nanocomposites showed superparamagnetic properties at 300 K.

关键词： magnetometer superparamagnetic ultra-micro thermogravimetry transmission

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High purity Mn

Xiaoqiang SHAN, Fenghua GUO, Wenqian XU, Xiaowei TENG

《能源前沿（英文）》 2017年第11卷第3期页码 383-400 doi: 10.1007/s11708-017-0485-3

摘要： Developing electrodes with high specific energy by using inexpensive manganese oxides is of great importance for aqueous electrochemical energy storage (EES) using non-Li charge carriers such as Na-or K-ions. However, the energy density of aqueous EES devices is generally limited by their narrow thermodynamic potential window (~1.23 V). In this paper, the synthesis of high purity layered Mn O nanoparticles through solid state thermal treatment of Mn O spinel nanoparticles, resulting in a chemical formula of [Mn ][Mn O ], evidenced by Rietveld refinement of synchrotron-based X-ray diffraction, has been reported. The electro-kinetic analyses obtained from cyclic voltammetry measurements in half-cells have demonstrated that Mn O electrode has a large overpotential (~ 0.6 V) towards gas evolution reactions, resulting in a stable potential window of 2.5 V in an aqueous electrolyte in half-cell measurements. Symmetric full-cells fabricated using Mn O electrodes can be operated within a stable 3.0 V potential window for 5000 galvanostatic cycles, exhibiting a stable electrode capacity of about 103 mAh/g at a C-rate of 95 with nearly 100% coulombic efficiency and 96% energy efficiency.

关键词： manganese oxides Mn₅O₈ high voltage aqueous Na-ion storage

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Ultrasound-assisted co-precipitation synthesis of mesoporous Co3O4–CeO2 composite oxides for highly selective

《化学科学与工程前沿（英文）》 2022年第16卷第8期页码 1211-1223 doi: 10.1007/s11705-022-2145-3

摘要： The one-step highly selective oxidation of cyclohexane into cyclohexanone and cyclohexanol as the essential intermediates of nylon-6 and nylon-66 is considerably challenging. Therefore, an efficient and low-cost catalyst must be urgently developed to improve the efficiency of this process. In this study, a Co₃O₄–CeO₂ composite oxide catalyst was successfully prepared through ultrasound-assisted co-precipitation. This catalyst exhibited a higher selectivity to KA-oil, which was benefited from the synergistic effects between Co³⁺/Co²⁺ and Ce⁴⁺/Ce³⁺ redox pairs, than bulk CeO₂ and/or Co₃O₄. Under the optimum reaction conditions, 89.6% selectivity to KA-oil with a cyclohexane conversion of 5.8% was achieved over Co₃O₄–CeO₂. Its catalytic performance remained unchanged after five runs. Using the synergistic effects between the redox pairs of different transition metals, this study provides a feasible strategy to design high-performance catalysts for the selective oxidation of alkanes.

关键词： Co₃O₄–CeO₂ composite oxides cyclohexanone cyclohexanol ultrasonic-assisted co-precipitation selective oxidation solvent-free

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On the monolayer dispersion behavior of Co₃O₄ on HZSM-5 support: designing applicable

《化学科学与工程前沿（英文）》 2023年第17卷第11期页码 1741-1754 doi: 10.1007/s11705-023-2332-x

摘要： Based on monolayer dispersion theory, Co₃O₄/ZSM-5 catalysts with different loadings have been prepared for selective catalytic reduction of nitrogen oxides by ammonia. Co₃O₄ can spontaneously disperse on HZSM-5 support with a monolayer dispersion threshold of 0.061 mmol 100 m^–2, equaling to a weight percentage around 4.5%. It has been revealed that the quantities of surface active oxygen (O₂^–) and acid sites are crucial for the reaction, which can adsorb and activate NO_x and NH₃ reactants effectively. Below the monolayer dispersion threshold, Co₃O₄ is finely dispersed as sub-monolayers or monolayers and in an amorphous state, which is favorable to generate the two kinds of active sites, hence promoting the performance of ammonia selective catalytic reduction of nitrogen oxide. However, the formation of crystalline Co₃O₄ above the capacity is harmful to the reaction performance. 4% Co₃O₄/ZSM-5, the catalyst close to the monolayer dispersion capacity, possesses the most abundant active O₂^– species and acidic sites, thereby demonstrating the best reaction performance in all the samples. It is proposed the optimal Co₃O₄/ZSM-5 catalyst can be prepared by loading the capacity amount of Co₃O₄ onto HZSM-5 support.

关键词： Co₃O₄/ZSM-5 NO_x-SCR by NH₃ monolayer dispersion threshold effect surface acid sites surface active O₂^– anions

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ZnFe₂O₄ deposited on BiOCl with exposed (001) and (010) facets for photocatalytic

Guixian Song, Xionggang Wu, Feng Xin, Xiaohong Yin

《化学科学与工程前沿（英文）》 2017年第11卷第2期页码 197-204 doi: 10.1007/s11705-016-1606-y

摘要： ZnFe O -BiOCl composites were prepared by both hydrothermal and direct precipitation processes and the structures and properties of the samples were characterized by various instrumental techniques. The samples were then used as catalysts for the photocatalytic reduction of CO in cyclohexanol under ultraviolet irradiation to give cyclohexanone (CH) and cyclohexyl formate (CF). The photocatalytic CO reduction activities over the hydrothermally prepared ZnFe O -BiOCl composites were higher than those over the directly-precipitated composites. This is because compared to the direct-precipitation sample, the ZnFe O nanoparticles in the hydrothermal sample were smaller and more uniformly distributed on the surface of BiOCl and so more heterojunctions were formed. Higher CF and CH yields were obtained for the pure BiOCl and BiOCl composite samples with more exposed (001) facets than for the samples with more exposed (010) facets. This is due to the higher density of oxygen atoms in the exposed (001) facets, which creates more oxygen vacancies, and thereby improves the separation efficiency of the electron-hole pairs. More importantly, irradiation of the (001) facets with ultraviolet light produces photo-generated electrons which is helpful for the reduction of CO to ·CO . The mechanism for the photocatalytic reduction of CO in cyclohexanol over ZnFe O -BiOCl composites with exposed (001) facets involves electron transfer and carbon radical formation.

关键词： reduction of CO₂ cyclohexanol ZnFe₂O₄ deposited BiOCl facet composite photocatalyst

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Phase equilibrium of the ternary system of NH 4 Cl—CaCl 2 —H 2 O at 50°C

Xia LI, Junsheng YUAN, Zhiyong JI, Jianxin CHEN,

《化学科学与工程前沿（英文）》 2010年第4卷第1期页码 75-77 doi: 10.1007/s11705-009-0296-0

摘要： The equilibrium data on the ternary system of NHCl—CaCl—HO at 50°C were investigated using the wet-residue method. The experimental results show that there are three pure phase crystal areas of NHCl, 2NHCl·CaCl·3HO and CaCl·2HO, two mixture phase crystal areas of NHCl and 2NHCl·CaCl·3HO, and 2NHCl·CaCl·3HO and CaCl·2HO in the system. A new hydration double salt (2NHCl·CaCl·3HO) was found in the ternary equilibrium system for the first time.

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标题作者时间类型操作

Li₄SiO₄-coated LiNi_0.5Mn_1.5O₄ as the high performance

Shifeng YANG, Wenfeng REN, Jian CHEN

期刊论文

Effects of gradient concentration on the microstructure and electrochemical performance of LiNi

Wenming Li, Weijian Tang, Maoqin Qiu, Qiuge Zhang, Muhammad Irfan, Zeheng Yang, Weixin Zhang

期刊论文

CO₂ methanation and co-methanation of CO and CO₂ over Mn-promoted Ni/Al₂O₃ catalysts

Kechao Zhao,Zhenhua Li,Li Bian

期刊论文

Large-scale synthesis of isolated Mn2O3 nanotube/fiber with ferric nitrate as catalyst

ZHANG Aifei, LIU Jiping, L? Guangshu

期刊论文

Construction of nitrogen-doped carbon cladding LiMnO film electrode with enhanced stability for electrochemically selective extraction of lithium ions

期刊论文

Rh₂O₃/hexagonal CePO₄ nanocatalysts for N₂O decomposition

Huan Liu, Zhen Ma

期刊论文

ZnFe₂O₄/BiVO₄ Z-scheme heterojunction for efficient visible-light photocatalytic

期刊论文

NiCo2O4@quinone-rich N–C core–shell nanowires as composite electrode for electric double layer capacitor

期刊论文

Pd/Fe3O4 supported on bio-waste derived cellulosic-carbon as a nanocatalyst for C–C coupling and electrocatalytic

期刊论文

Preparation and property characterization of PAA/Fe3O4 nanocomposite

WEI Shanshan, ZHANG Yi, XU Jiarui