INTERNATIONAL JOURNAL OF HYDROGEN ENERGY
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2021
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IF 5.816
Wenjuan Li,Shuo Yu,Liang Zhang,Jianfa Chen,Weiguo Cao,Yanhua Lan
The pyrolysis and combustion mechanism of the hydrocarbon fuel has important scientific and practical significance. However, it is difficult to detect the whole intermediates and products using traditional methods, which brings trouble to the analysis of the reaction process. In this paper, the microscopic reaction mechanism and the main products of n- eicosane (C 20 H 42 ) were simulated based on the reactive force field molecular dynamics (ReaxFF-MD). The effects of temperature (2000–3500 K) and oxygen on the initial decomposition, the distribution of main products, and the reactive pathways of C 20 H 42 fuel were studied to determine its reaction mechanism. The initial decomposition of C 20 H 42 was mainly initiated by small alkyl radicals in pyrolysis, and by the oxygen-containing radicals in combustion. The participation of oxygen had a greater effect on accelerating the decomposition reaction . The reactions involving oxygen of C 20 H 42 initial decomposition accounted for 87.5% of the total reactions at 2000 K. Moreover, the detailed distribution and formation pathways of the main products of H 2 , C 2 H 4 , CH 4 , H 2 O, CO, and CO 2 were depicted to construct the overall reaction mechanism of C 20 H 42 . •H radical formed from the composition of C 2 H 4 was exactly consistent with the •H radical consumed by the generation of CH 4 and H 2 in the pyrolysis stage. The feasibility of the simulation method was verified by the result of thermal analysis. The results are helpful for further research on the reaction mechanism of hydrocarbon fuels.
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BULLETIN OF THE KOREAN CHEMICAL SOCIETY
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2020
·Vol. 41
·期 3
·261-265
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IF 0.611
Yue-Xin Liu,Shi-Man Du,Jie Cao,Wen-sheng Huang,Xiao-Ru Zhang,Bao-Ping Qi,Sheng-Hui Zhang
N-doped porous biochar (NPB) with large conjugated systems could not only be used as enrichment carriers but also be in favor of electron transport in the electrochemical detection. The NPB-modified electrode was fabricated for the simultaneous detection of catechol (CA) and hydroquinone (HQ) to enhance the signal-to-noise ratio and further improve the sensitivity. A detection limit as low as 37 and 47 nM was achieved for CA and HQ, respectively. The proposed strategy with the merits of high sensitivity, selectivity, and reproducibility exhibited a great potential for the detection.
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CHEMICAL ENGINEERING JOURNAL
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2019
·
IF 8.355
Shizong Wang,Jianlong Wang
High efficient and stable activator is desired for the sulfate radical-based wastewater treatment. Cobalt sulfide and cobalt oxide have high catalytic activity for peroxymonosulfate (PMS), but poor stability. Here, a novel composite, nano Co 9 S 8 and CoO encapsulated by nitrogen and sulfur co-doped sludge-derived biochar (CoO/Co 9 S 8 @N-S-BC) was synthesized, characterized and applied for activating PMS. The results showed that CoO/Co 9 S 8 @N-S-BC can effectively activate PMS for sulfamethoxazole (SMX) degradation, and 0.08 mM of SMX could be completely degraded within 10 min. The influencing factors, such as pH, temperature, chloridion, carbonate and humic acid were investigated. The SMX degradation conformed to pseudo first-order kinetics with rate constant of 0.379 min −1 . Sulfate radicals (dominant) and hydroxyl radicals contributed to SMX degradation. Carbon defects, pyridinic N, quaternary N, the carbon atoms next to pyridinic N, C O groups, -C-S-C and Co(II), all contributed to PMS activation.
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JOURNAL OF ALLOYS AND COMPOUNDS
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2019
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IF 4.175
Zhaoyang Wang,Fangyu Xiong,Haizheng Tao,Yuanzheng Yue
To optimize the Na 0·74 CoO 2 -based cathode materials for sodium-ion batteries, we fabricated a series of Na 0·74 CoO 2 /C/N-based composites by sintering the mixtures of ZIF-4(Co) (Co [H 2 C 3 N 2 ] 2 ) and Na 2 CO 3 , which possess various molar Na/Co ratios (X = 0.5, 0.6, 0.7, 0.8, 0.9, 1.0, 1.1, 1.2 and 2.0), at 800 °C for 6 h. By performing the electrochemical characterizations, we found that the composite with X = 0.7 (NC-0.7) exhibits the optimum sodium storage performance, i.e., excellent Na + storage capacity (107.9 mA h g −1 at 0.1 C), and high cycling stability (74% of the discharge capacity retention after 500 cycles at 10 C). In addition, for this NC-0.7 composite, we discovered a large difference (48.1 mA h g −1 ) between the charging (59.8 mA h g −1 ) and discharging (107.9 mA h g −1 ) capacities for the first cycle. Using the X-ray photoelectron spectroscopy, high-resolution transmission electron microscopy, and scanning transmission electron microscope, we clarified the atomic-scale origin of the large capacity difference, and revealed the role of the amorphous phase in the as-prepared Na 0·74 CoO 2 /C/N composite cathode.
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ACS Applied Materials & Interfaces
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2019
·
IF 8.456
Zhenyu Wang,Yu Huang,Meijuan Chen,Xianjin Shi,Yufei Zhang,Junji Cao,Wingkei Ho,Shun Cheng Lee
The development of catalysts that effectively activate target pollutants and promote their complete conversion is an admirable objective in the environmental photocatalysis field. In this work, graphitic carbon nitride (g-C3N4) microtubes with tunable N-vacancy concentrations were controllably fabricated using an in situ soft-chemical method. The morphological evolution of g-C3N4, from the bulk to the porous tubular architecture, is discussed in detail with the aid of time-resolved hydrothermal experiments. We found that the NO removal ratio and apparent reaction rate constant of the g-C3N4 microtubes were 1.8 and 2.6 times higher than those of pristine g-C3N4, respectively. By combining detailed experimental characterization and density functional theory calculations, the effects of N-vacancies in the g-C3N4 microtubes on O2 and NO adsorption activation, electron capture, and electronic structure were systematically investigated. These results demonstrate that surface N-vacancies act as specific sites for the adsorption activation of reactants and photoinduced electron capture, while enhancing the light-absorbing capability of g-C3N4. Moreover, the porous wall structures of the as-prepared g-C3N4 microtubes facilitate the diffusion of reactants, and their tubular architectures favor the oriented transfer of charge carriers. The intermediates formed during photocatalytic NO removal processes were identified by in situ diffuse reflectance infrared Fourier transform spectroscopy, and different reaction pathways over pristine and N-deficient g-C3N4 are proposed. This study provides a feasible strategy for air pollution control over g-C3N4 by introducing N-vacancy and porous tubular architecture simultaneously.
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PubMed
高影响因子
JOURNAL OF POWER SOURCES
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2019
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IF 7.467
Yun Gu,Le-Qing Fan,Jian-Ling Huang,Cheng-Long Geng,Jian-Ming Lin,Miao-Liang Huang,Yun-Fang Huang,Ji-Huai Wu
This work reports the preparation of N-doped reduced graphene oxide decorated NiSe 2 nanoparticles (N-rGO/NiSe 2 ) in the presence of different amount of graphene oxide reactant by a simple two-step process, which contains hydrothermal preparation of Ni(OH) 2 precursor and then solvothermal synthesis of N-rGO/NiSe 2 composites with different content of N-rGO. The as-prepared N-rGO/NiSe 2 composites is characterized by power X-ray diffraction, Raman spectroscopy , high-resolution X-ray photoelectron spectroscopy, field emission scanning electron microscopy , transmission electron microscopy, energy-dispersive X-ray spectroscopy and N 2 adsorption–desorption isotherm. The results show that N-rGO acts as supporter of NiSe 2 nanoparticles to prevent them from aggregation, leading to the increase in specific surface area and electrical conductivity of material. The optimized N-rGO/NiSe 2 composite can deliver high specific capacitance of 2451.4 F g −1 at a current density of 1 A g −1 . Using activated carbon (AC) as negative electrode and the optimized N-rGO/NiSe 2 composite as positive electrode , an asymmetric supercapacitor is constructed. This fabricated asymmetric supercapacitor can work stably under the potential window of 0–1.6 V, and presents the maximum energy density of 40.5 Wh kg −1 at a power density of 841.5 W kg −1 . Moreover, the N-rGO/NiSe 2 //AC asymmetric supercapacitor exhibits good cyclic stability.
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CERAMICS INTERNATIONAL
·
2019
·
IF 3.45
Honghong Lei,Peng Jiang,Bin Li,Yuncheng Zhou,Rui Zhang,Jianlei Kuang,Wenbin Cao,Wei Wang
The (S, N) co-doped Ba 2 In 2- x Cr x O 5+ y (0 ≤ x ≤ 0.5) oxides are successfully obtained by mixing the Ba 2 In 2- x Cr x O 5+ y oxides and thiourea through a simple ball milling method followed by sintering at 400 °C for 3 h. The colors of the compounds change from orange-brown to yellow-green after reacting with thiourea. When Cr amount is small ( x = 0.1), the crystal structure of (S, N) co-doped Ba 2 In 2- x Cr x O 5+ y is orthorhombic Ba 2 In 2 O 5 phase. When x ≥ 0.3, the crystal structure of the sample is cubic BaInO 2.5 phase. And this phase transition is the same as Ba 2 In 2- x Cr x O 5+ y . XPS results reveal that Cr 6+ in Ba 2 In 2- x Cr x O 5+ y (0 ≤ x ≤ 0.5) oxides are reduced to Cr 3+ after sintering. S exists in both cation and anion forms, and N exists in substitutional forms. UV–Vis analysis indicates that the yellow-green hue comes from the d-d transition of Cr 3+ , and the doping of S, N ions leads to a red shift of the absorption edge of the samples.
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RSC Advances
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2019
·Vol. 9
·期 16
·8753-8758
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IF 3.049
Zhilong Xu,Lei Fan,Xiangying Ni,Jie Han,Rong Guo
Tin (Sn) has wide prospects in applications as an anode electrode material for Li-ion batteries, due to its high theoretical specific capacity. However, the large volume expansion of Sn during the charge–discharge process causes a performance reduction of lithium-ion batteries (LIBs). Here, Sn encapsulated N-doped porous carbon fibers (Sn/NPCFs) were synthesized through an electrospinning method with a pyrolysis process. This structure was beneficial for the lithium ion/electron diffusion and buffered the large volume change. By adjusting the amount of Sn, the hybrid carbon fibers with different Sn/carbon ratios could be prepared, and the morphology, composition and properties of the Sn/NPCFs were characterized systematically. The results indicated that the Sn/NPCFs with a Sn-precursor/polymer weight ratio at 0.5 : 1 showed the best cycling stability and specific capacity, preserving the specific capacity of 400 mA h g−1 at the current density of 500 mA g−1 even after 100 cycles.
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PubMed
高影响因子
CHEMICAL ENGINEERING JOURNAL
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2019
·
IF 8.355
Xingzheng Liu,Junsheng Jin,Yueliang Chen,Boting Lu,Qian Sun,Jiexin Wang,Jian-feng Chen,Yuan Le
Poly ( n -butyl cyanoacrylate) (PBCA) nanoparticles are widely used as biocompatible and bio-erosive materials in a range of biomedical applications, especially for drug delivery systems. This paper reports a novel synthesis method of PBCA nanoparticles with high productivities and purities in a rotating packed bed. The particle size and molecular weight of PBCA nanoparticles were controlled by adjusting the high-gravity factor, surfactant concentration, pH, temperature and monomer concentration. The high-gravity factor shows an obvious influence on the particle sizes, while it has few effects on molecular weight. The surfactant concentration and pH also affect molecular weight and particle sizes. Moreover, compared with conventional stirred tank, the reaction time of RPB procedure was dramatically reduced from 12 h to 2 h, and the purity of products increased from about 93% to 96%. Furthermore, when the molecular weight of PBCA increased, the in vitro cytotoxicity to Hep G2 cells firstly increased and then decreased, and the cellular uptake was improved. In summary, PBCA with controllable molecular weight and particle sizes can be synthesized using a facile high-gravity method.
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JOURNAL OF MOLECULAR LIQUIDS
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2019
·
IF 4.561
Yinghui Wang,Xuelai Zhang,Jun Ji,Yuyang Li,Jotham Muthoka Munyalo,Biao Liu,Xiaofeng Xu,Sheng Liu
Considering the low thermal conductivity of organic phase change materials (PCMs), a modification of Octanoic acid (OA) and Myristic acid (MA) binary mixture with a mass ratio of 87:13 was studied. The influence of expanded graphite (EG) and Hydroxylated multi-walled carbon nanotubes (MWCNTs) on the thermal conductivity of OA-MA were compared and analyzed. The morphology of these two nanoparticals and OA-MA/EG PCM were measured by scanning electronic microscope (SEM). 7 wt% EG was finally selected as the additive to modify the thermal conductivity of OA-MA. By differential scanning calorimeter (DSC), the phase transition temperature was measured to be 6.8 °C and the enthalpy of fusion was 136.3 J/g. The thermal conductivity of OA-MA/EG was 0.9975 W/(m·K) tested by Hot Disk, which remarkably increased by 235.75% compared with the thermal conductivity of OA-MA. Undergoing 100 freeze-thaw cycles, the properties of the OA-MA/EG did not change significantly, which shows the composite PCM is especially suitable for its application in pharmaceutical refrigerated transport system.
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ACS Catalysis
·
2019
·
IF 12.221
Xingxing Li,Yu Pan,Hong Yi,Jingcheng Hu,Dali Yang,Fengzhi Lv,Wendian Li,Jinping Zhou,Xiaojun Wu,Aiwen Lei,Lina Zhang
Improving the selectivity and retaining the efficiency of catalysts are essential for industrial processes and remain a great challenge. Herein, we developed a facile route to synthesize Pd nanocubes (NCs) using Eosin Y as the photosensitizer under visible light. Subsequently, Pd NCs were uniformly loaded on N-doped carbon nanofibrous microspheres (NCMs) from carbonated chitin microspheres. This Pd NCs@NCM exhibited high reactivity and selectivity in alkyne semihydrogenation. For example, the hydrogenations of phenylacetylene to styrene and of 3-phenyl-2-propyn-1-ol to (Z)-cinnamyl alcohol were 12.9 and 18.3 times faster with Pd NCs@NCM than with Lindlar catalyst. According to the Mott–Schottky effect, loading of Pd NCs on N-doped carbon constructed a rectifying contact and decreased the electron density of Pd NCs. Density functional theory (DFT) calculations suggested that the high concentration of holes doped in Pd NCs weakened the interaction of alkenes on the Pd (100) facet and prevented further hydrogenation for a long time; this period of durable time is very helpful in chemical manufacturing. Thus, Pd NCs@NCM maintained both high reactivity and selectivity in comparison with surface-modified catalysts. This work provides an alternative strategy to design Mott–Schottky catalysts for selective hydrogenation reactions.
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GREEN CHEMISTRY
·
2019
·Vol. 22
·期 3
·742-752
·
IF 9.405
Xiwei Hu,Xun Sun,Qiang Song,Yangyang Zhu,Yu Long,Zhengping Dong
Metal-free carbon catalysts with excellent catalytic performance have drawn much research attention recently. Herein, polymer-derived N,S co-doped carbon catalysts (PDNSC-X) with a hierarchically porous structure were facilely prepared by a cost-effective and convenient strategy via carbonization of a N- and S atom-containing polymer precursor and were subsequently used as efficient metal-free catalysts. The catalytic activity of the as-fabricated PDNSC-800 was greater than those of other reported heteroatom-doped carbon catalysts in catalytic reduction of various nitroarenes. The high catalytic activity of PDNSC-800 was related to the synergistic effects of a high surface area, a hierarchically porous structure, abundant N- and S-containing active sites, and defect formation. In addition, the close relationship between the N species (especially pyrrolic N) and high selectivity in metal-free catalytic synthesis was investigated in the reduction of nitroarenes and selective oxidation of ethylbenzene. This study may provide a new strategy to fabricate specific heteroatom-doped metal-free carbon catalysts for environmentally friendly efficient organic transformation.
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