Science China-Materials
·
2022
·Vol. 66
·期 1
·169-178
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IF 8.64
Wei Haisheng,Song Huaxing,Ren Yujing,Yan Xiaorui,Fang Geqian,Wang Wenhua,Ren Wanzhong,Zhu Mingyuan,Lin Jian
Metal-organic frameworks (MOFs) derived Co-based catalysts have received extensive attention in the chemoselective hydrogenation of nitroarenes, while they usually require a lot of solvent during the synthesis and identification of active species. This study explores a solid-phase synthesis strategy to obtain MOF precursors without using any solvent, which is then foamed and pyrolyzed to synthesize the Co@NC-X catalyst. It was found that a nitrogen-doped graphene shell can well encapsulate the Co nanoparticles. The resulting catalyst, which was pyrolyzed at 800°C, exhibited ~100% conversion for the hydrogenation of 3-nitrostyrene and >99% selectivity to 3-vinylaniline. This catalyst also showed excellent stability and good substrate universality for the hydrogenation of extensive substituted nitroarenes. Various characterizations revealed a positive relationship between the catalytic performance and the content of Co—N species tuned by pyrolysis temperature. This work provides a novel and green strategy to design an efficient Co-based catalyst for chemoselective hydrogenation.
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高影响因子
OPTICAL MATERIALS
·
2021
·
IF 3.08
Kun Zhu,Haitao Lv,Yanmin Wang,Zhidong Pan
Sm 3+ doped calcium stannate (CaSnO 3 :Sm 3+ ) and (Sm 3+ , Zr 4+ )-co-doped calcium stannate (CaSnO 3 :Sm 3+ , Zr 4+ ) photoluminescent phosphors were synthesized via co-precipitation and subsequent sintering in oxidizing atmosphere at 1400 °C for 60 min with SnCl 4 ·5H 2 O, CaCl 2 ·2H 2 O, ZrO(NO 3 ) 2 · x H 2 O and Sm 2 O 3 as main raw materials. The synthesized samples were characterized by X-ray diffraction, scanning electron microscopy, energy dispersive spectroscopy, photoluminescent spectroscopy, luminescent decay curves, afterglow spectroscopy and thermo-luminescent glow curves. The results show that CaSnO 3 pure phase is synthesized in co-precipitation reaction at an optimum molar ratio of CaCl 2 ·2H 2 O:SnCl 4 ·5H 2 O of 1.4:1.0 and subsequent sintering at 1400 °C for 60 min. Calcium stannate as a host matrix can be doped with Sm 3+ ions or co-doped with Sm 3+ /Zr 4+ ions for the formation of white photoluminescent phosphors. CaSnO 3 :0.03Sm 3+ phosphor has an optimum photoluminescent intensity. Also, the fluorescent emission intensity of CaSnO 3 :0.03Sm 3+ ，0.04Zr 4+ phosphor under excitation of 365 nm wavelength can be enhanced due to Zr 4+ ions doping at an optimum doping amount y of 0.04. The CIE 1931 chromaticity coordinates change from (0.3600, 0.3535) for CaSnO 3 :0.03Sm 3+ phosphor to (0.3622, 0.3574) for CaSnO 3 :0.03Sm 3+ , 0.04Zr 4+ phosphor as the average crystalline size decreases from 71.5 to 68.3 nm and the unit cell volume increases from 0.2686 to 0.2775 nm 3 . In addition, the electron transition mechanism for the photoluminescent and long afterglow properties was also discussed.
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JOURNAL OF ALLOYS AND COMPOUNDS
·
2021
·
IF 5.316
Qianer Xu,Haifeng Zhou,Qunli Tang,Aiping Hu,Yali Xu,Yuping Shen,Chao Kang,You Zhou,Xiaohua Chen
Sluggish reaction kinetics of lithium-sulfur (Li-S) battery is the key issue affecting cycle capacity and rate performance. Highly conductive and catalytically active sulfur host is still a research hotspot in recent years. Herein, the sulfur host of Co nanoparticles anchored on the Co-N x active centers grafted nitrogen-doped graphene (Co/Co-N x @NG) with high catalytic activity and electrical conductivity was prepared via a simple and feasible in situ method. The cobalt-based nanocatalytic center exhibits efficient sulfur conversion efficiency. Moreover, the Co-N x coordination group is beneficial to inhibit the agglomeration of cobalt nanoparticles to form large particles and further improve the catalytic activity. In addition, the graphene structure formed at low temperature based on the two-dimensional guide of dicyandiamide in combination with the catalytic graphitization of cobalt nanoparticles has excellent electrical conductivity. Owing to the high catalytic activity, appropriate adsorption ability, and excellent electrical conductivity, the Co/Co-N x @NG applied as sulfur cathode matrix exhibits high capacities of 1300.3 mA h g −1 at 0.1 C and 884.2 mA h g −1 at 2 C, and good cycling stability with a capacity decay of only 0.069% per cycle at 2 C for 705 cycles.
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Journal of Environmental Chemical Engineering
·
2021
·
IF 5.909
Peng Liu,Dengjie Zhong,Yunlan Xu,Nianbing Zhong,Guangjun He
Co/Fe co-doped porous graphite carbon (Co/Fe-PGC) nanocomposites were successfully prepared by one-step pyrolysis with CoFe-MOF, in which the Co/Fe nanoparticles were uniformly coated on porous graphite carbon derived from MOF. It was used to microelectrolysis-Fenton degrade rhodamine B through the main active substance ∙OH. The color and TOC removal rate of 100 mg/L rhodamine B reached 99.41% and 64.6%, respectively, for 30 min. Rhodamine B was degraded into small molecular organic acids, alcohols and lipids by N-demethylation and chromophore cleavage, until it was finally degraded into CO 2 and H 2 O, and no new colored organics were produced in the degradation process. The degradation process follows the first-order reaction kinetics, and its rate constant is much higher than that of the previous similar studies. The excellent catalytic performance of Co/Fe-PGC catalyst is attributed to the coupling effect of micro-electrolysis and Fenton reaction, and the acceleration of cobalt on electron transport and Fe 2+ reduction. Co 0 /Fe 0 undergoes galvanic corrosion to generate Co 2+ /Fe 2+ and H 2 O 2 , and then these products undergo Fenton reaction to generate Co 3+ /Fe 3+ and ∙OH, thus forming a circulating system of Co 3+ /Fe 3+ and Co 2+ /Fe 2+ , enhancing the activation of H 2 O 2 and ensuring the efficient degradation of RhB.
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ACS Sustainable Chemistry & Engineering
·
2020
·
IF 7.632
Qingqing Zha,Mingxia Li,Zihao Liu,Yonghong Ni
Metal–organic frameworks (MOFs) have attracted much interest in electrocatalysis as promising catalysts in recent years. However, it still remains a challenge to directly use MOF-based materials as bifunctional electrocatalysts for overall water splitting. Herein, a hierarchical Co,Fe-MOF-74/Co/carbon cloth (CC) three-layer hybrid electrode is synthesized by a simple electrochemical deposition technology with subsequent solvothermal treatment. Electrochemical performance investigations show that the as-constructed Co,Fe-MOF-74/Co/CC electrode exhibits impressive electrocatalytic activity for full water splitting, which only requires a low overpotential of 226 mV@20 mA cm–2 for the oxygen evolution reaction (OER) and 94 mV@–10 mA cm–2 for the hydrogen evolution reaction (HER), respectively. Employing the as-constructed electrode as the anode and cathode in a two-electrode setup simultaneously, only 1.65 V of the voltage is needed to deliver the current density of 20 mA cm–2. The above excellent electrochemical performances should be attributed to the specific architecture, the synergistic effect of the Co and Fe species, and the superhydrophilic surface of the catalyst. More importantly, further investigations uncover that metal hydroxides and oxyhydroxides produced in situ during electrochemical tests are the veritable active species, which promote the high catalytic activity of the present catalyst.
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SEPARATION AND PURIFICATION TECHNOLOGY
·
2022
·
IF 9.136
Ziyi Xiao,Rui Wu,Tingting Shu,Yingxi Wang,Ling Li
In order to further improve the catalytic performance of MIL-101, cobalt-doped MIL-101(Fe,Co) was synthesized by solvothermal method. By adjusting the ratio of cobalt doping, the MIL-101(Fe,Co 20% ) with the best catalytic activity was obtained. The activation performance of MIL-101(Fe,Co 20% ) for peroxymonosulfate (PMS) was studied using Rhodamine B (RhB) as a pollutant model. The experimental results proved MIL-101(Fe,Co 20% ) with much better catalytic performance than MIL-101(Fe), which can degrade more than 99% of RhB within 15 min. The effects of initial solution pH and coexisting anions in water on the degradation of RhB were further discussed. The results showed that MIL-101(Fe,Co 20% ) was with excellent stability and degradation efficiency can still keep above 90% after five cycles. The free radical quenching experiments were further studied to explore the degradation mechanism. It can be concluded that SO 4 - · was the main active free radical for the degradation of RhB. The possible intermediate products in the degradation process of RhB were analyzed by LC-MS. Combined with the comparison of XPS before and after the reaction, the possible reaction mechanism of RhB degradation process was inferred.
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SEPARATION AND PURIFICATION TECHNOLOGY
·
2023
·
IF 8.6
Zhiliang Ou,Jingyu Ran,Huayu Qiu,Xin Huang,Changlei Qin
Ni–Co bimetal catalysts showed the resistance to carbon deposition in DRM, and Co segregation on Ni surface plays very important role, but the underlying mechanism remains unclear. Hence, in current research, Ni and Ni–Co bimetal catalysts were prepared, and fixed-bed tests, characterizations and DFT calculations were carried out to uncover the effect of doped Co on the carbon formation and elimination process. DFT calculations suggested that Co segregation could promote the transfer of charge from the surface to CO 2 and further affect CO 2 activation. To some extent, the higher the Co concentrations on Ni surface, the more charge in adsorbed CO 2 , and the stronger ability for CO 2 activation, which could produce more O and OH species to participate in CH consumption and C elimination. Furthermore, Co segregation could promote CH oxidation and C hydrogenation, which could inhibit the formation of carbon deposition and promote the C elimination. In addition, DFT calculations results were verified by experiments and characterizations, and found that Co segregation could reduce the amount of carbon deposition and lower the graphitization degree of carbon deposition, thus the resistance to carbon deposition in Ni–Co bimetal catalysts is improved.
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DALTON TRANSACTIONS
·
2023
·Vol. 52
·期 28
·9744-9756
·
IF 4
Yanxia Wang,Xiude Hu
The development of new, efficient noble-metal-free photocatalysts is of great significance for the photocatalytic hydrogen evolution reaction. Herein, Co9S8 with a hollow polyhedral structure was synthesized by in situ sulfurization of ZIF-67, and subsequently, Co9S8@Ni2P composite photocatalytic materials were prepared by loading Ni2P on the surface of Co9S8 through a solvothermal method based on a morphology regulation strategy. The design of the 3D@0D spatial structure of Co9S8@Ni2P is favorable for the formation of photocatalytic hydrogen evolution active sites. Due to the excellent metal conductivity of Ni2P, Ni2P as a cocatalyst can accelerate the separation of photogenerated electrons from holes in Co9S8, thus providing a large number of available photogenerated electrons for photocatalytic reactions. It is worth mentioning that a Co–P chemical bond is formed between Co9S8 and Ni2P, which plays an active role in the transport of photogenerated electrons. The densities of states of Co9S8 and Ni2P were determined by density functional theory (DFT) calculations. The reduction of the hydrogen evolution overpotential and the formation of efficient charge-carrier transport channels on Co9S8@Ni2P were confirmed by a series of electrochemical and fluorescence tests. This study provides a new idea for the design of highly active noble-metal-free materials for the photocatalytic hydrogen evolution reaction.
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PubMed
高影响因子
FUEL
·
2023
·
IF 7.4
Suqian Gu,Zhiqiang Xu,Yunxiang Dai,Yang Chen,Yangguang Ren,Yanan Tu,Le Yang,Mengyun Shi
Coal gasification wastewater (CGW) as a substitute for clean water to prepare coal water slurry, which serves as gasification/combustion feedstock, can simultaneously achieve wastewater management and resource utilization. The purpose of this work was to investigate the effects of internal components (i.e., oils, phenols, nitrogen heterocyclic compounds, and inorganic cations) in CGW on the slurryability and dispersion/aggregation behavior of lignite and their co-slurrying mechanisms through experimental and the extended DLVO (eDLVO) theoretical calculations. Results showed that compared to lignite water slurry (LWS), the maximum solids concentration ( ω max ) of coal gasification wastewater slurry (CWWS) increased by 0.80%, with a lower pseudo-plasticity. The organic compounds adsorbed competitively on the hydrophobic regions of lignite improved the slurrying capability of CWWS by decreasing the wettability, Zeta potential, roughness and pore structure of the particles. By contrast, the static stability of CWWS decreased, and its kinetic stability index ( TSI ) increased from 0.23 to 0.33. From the backscattering spectra, dodecane caused the creaming process of the slurry, while the clarification process was attributed to phenol and nitrogen heterocyclic compounds. Inorganic cations, especially NH 4 + and Ca 2+ , significantly reduced the hydrophilic and negative charges on the particle surface, which were the main unfavorable factors leading to particle aggregation and sedimentation. The eDLVO theoretical calculation results exhibited that inter-particle interaction in CWWS was determined by the hydrophobic energy ( E h ) and electrostatic energy ( E e ) and their dropped from 1.79 × 10 −16 J and 5.16 × 10 −17 J to −4.67 × 10 −16 J and 2.59 × 10 −17 J respectively.
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高影响因子
JOURNAL OF POLYMER RESEARCH
·
2023
·Vol. 30
·期 5
·1-15
·
IF 2.8
Bai Xiaodong,Li Ke,Hu Hua,Yan Yancheng,Luo Yumei
A new anionic polymer poly(acrylamide-co-N-vinylpyrrolidone-co-sodium p-styrene sulfonate) (abbreviated as PANS) is synthesized by using acrylamide(AM), N-vinylpyrrolidone(NVP) and sodium p-styrene sulfonate(SSS) as monomers and used as filter loss agents. The optimal synthesis process conditions are explored by orthogonal experiments: molar ratio is AM:NVP:SSS = 3.5; 2; 1, the monomer concentration is 35 wt%, the initiator concentration is 0.40 wt%, the reaction temperature is 45 °C, and the reaction time is 4 h. Fourier infrared spectroscopy(FTIR)and nuclear magnetic resonance hydrogen spectroscopy( 1 HNMR) hydrogen spectroscopy are used to characterize it. Through thermogravimetric analysis(TG) testing, its temperature resistance is tested, and it is found that it has good thermal stability before 350 °C. The performance test is carried out using American Petroleum Institute(API) evaluation criteria, and it is found that the filter loss before aging is 7.5 mL under 2 wt% addition, and only 8 mL after aging. At the same time, after the addition of PANS, the salt resistance of drilling fluid after high temperature aging is improved, and the filtration loss after aging is only 8.25 mL under the addition of 12 wt% NaCl, while the filtration loss after aging is 8.2 mL under the addition of CaCl 2 at 3 wt%. Through Zeta potential and particle size analysis, after adding PANS, the particle size of clay particles can be greatly reduced after aging, and the zeta potential value of drilling fluid is optimized under calcium salt contamination.
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高影响因子
JOURNAL OF POWER SOURCES
·
2023
·
IF 9.2
Peihan Li,Xingyu Chen,Yifei Sun,Ting Chen,Bo Zhang,Fugen Li,Juan Zhou,Shaorong Wang
Solid Oxide Electrolysis Cell (SOEC) is an efficient green hydrogen production technology, which is a reverse of Solid Oxide Fuel Cell (SOFC). In this paper, an anode-supported SOEC produced via multi-layer organic co-tape casting with co-sintering process is investigated for high temperature steam electrolysis , carbon dioxide electrolysis, and co-electrolysis. SOEC cathode must maintain its electrocatalytic activity in a high temperature and humidity condition. La 0.75 Sr 0.25 Cr 0.5 Mn 0.5 O 3-δ (LSCM) is one of the most promising cathode materials because of its superior electrocatalytic ability and redox stability. The anode-supported structure of electrolysis cell reduces ohmic resistance obviously and LSCM cathode exhibits good catalytic performance. To evaluate the performance of co-electrolysis, a continuous voltage of 1 V is applied for 256 h with 60% H 2 O and 40% CO 2 at 750 °C. The anode-supported SOEC with LSM((La 0.8 Sr 0.2 ) 0.95 Mn 0.5 O 3-δ )/LSM-YSZ(Zr 0.92 Y 0.08 O 2-δ )/YSZ/LSCM structure has good electrochemical performance and durability under co-electrolysis conditions combined with the distribution relaxation of time analysis of impedance spectra.
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高影响因子
JOURNAL OF CATALYSIS
·
2023
·
IF 7.3
Yue Shen,Chun Chen,Zidan Zou,Zhi Hu,Zhen Fu,Wenchao Li,Shenglong Pan,Yunxia Zhang,Haimin Zhang,Zhixin Yu,Huijun Zhao,Guozhong Wang
Exploring the interactions among doping heteroatom, carbon and metal atoms has great potential to significantly enhance the catalytic performance and can gain an insightful understanding of the heterogeneous catalysis mechanism. Here, we present an N,P co-doped carbon-coated cobalt (Co@NPC) as a highly selective and water-durable catalyst applicable to aqueous-phase hydrogenation of cinnamaldehyde, featuring a precise control of products by adjusting N and P doping. These di-heteroatoms display a synergistic effect of geometry and electrons in Co@NPC, thus can selectively reduce C O to produce unsaturated alcohols. In contrast, Co@NC without P doping is highly active, but shows significant productivity of saturated alcohols under equivalent conditions. Theoretical calculations manifest that the electronegativity difference among N, C and P atoms leads to the interaction between electrons, thus can adjust the chemical states of the active metal and enhance the catalytic performance in hydrogenation. It provides a desirable way for regulating the catalysis of heterogeneous catalysts.
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