共查询到20条相似文献,搜索用时 218 毫秒
1.
Qi Xue Xin-Yu Bai Yue Zhao Ya-Nan Li Tian-Jiao Wang Hui-Ying Sun Fu-Min Li Pei Chen Pujun Jin Shi-Bin Yin Yu Chen 《Journal of Energy Chemistry》2022,(2):94-102
Inefficient electrocatalysts and high-power consumption are two thorny problems for electrochemical hydrogen(H2)production from acidic water electrolysis.Herein we report the one-pot precise synthesis of ultrafine Au core-Pt Au alloy shell nanowires(Au@PtxAu UFNWs).Among them,Au@Pt0.077 Au UFNWs exhibit the best performance for formic acid oxidation reaction(FAOR)and hydrogen evolution reaction(HER),which only require applied potentials of 0.29 V and-22.6 m V to achieve a current density of 10 m A cm-2,respectively.The corresponding formic acid electrolyzer realizes the electrochemical H2 production at a voltage of only 0.51 V with 10 m A cm-2 current density.Density functional theory(DFT)calculations reveal that the Au-riched Pt Au alloy structure can facilitates the direct oxidation pathway of FAOR and consequently elevates the FAOR activity of Au@Pt0.077 Au UFNWs.This work provides meaningful insights into the electrochemical H2 production from both the construction of advanced bifunctional electrocatalysts and the replacement of OER. 相似文献
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Jiaxiang Liu Haoshen Ma Zhipeng Wen Huiyang Li Jin Yang Nanbiao Pei Peng Zhang Jinbao Zhao 《Journal of Energy Chemistry》2022,(1):354-363
Lithium metal batteries are considered as high energy density battery systems with very promising prospects and have bee n widely studied.However,The uncon trollable plating/strippi ng behavior,infinite volume change and den drites formation of lithium metal anode restrict the applicati on.The unc on trolled n ucleati on of lithium caused by the non uniform multi-physical field distributions,can lead to the undesirable lithium deposition.Herein,a graphene composite uniformly loaded with Ag nano-particles(Ag NPs)is prepared through a facile Gamma ray irradiation method and assembled into self-supported film with layered structure(Ag-rGO film).Whe n such film is used as a lithium metal an ode host,the uncontrolled deposition is converted into a highly nucleation-induced process.On one hand,the Ag NPs distributed between the in terlayers of graphe ne can preferentially induce lithium nu cleati on and en able uniform deposition morphology of lithium between interlayers.On the other hand,the stable layered graphene structure can accommodate volume change,stabilize the interface between anode and electrolyte and inhibit dendrites formation.Therefore,the layered Ag-rGO film as anode host can reach a high Coulombic efficiency over 93.3% for 200 cycle(786 h)at a current density of 1 mA cm-2 for 2 mAh cm-2 in carbonate-based electrolyte.This work proposes a facile Gamma ray irradiation method to prepare metal/3D-skeleton structure as lithium anode host and demonstrates the potential to regulate the lithium metal deposition behaviors via manipulating the distribution of lithiophilic metal(e.g.Ag)in 3D frameworks.This may offer a practicable thinking for the subsequent design of the lithium metal anode. 相似文献
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中国纤维素乙醇技术的研究进展 总被引:1,自引:0,他引:1
中国面临着严重的能源短缺和环境污染问题,中国政府正在局部几个省份内政策性鼓励燃料乙醇生产和使用.尽管当前主要是用玉米和谷物作为生产乙醇的原料,然而中国具有大量潜在的低成本的纤维素生物质原料,可以极大地扩大乙醇的产量,降低原料成本.近20年来,由于技术的革命性进步,已使得纤维素乙醇的生产成本从4美元/加仑以上,降低至约1.2-1.5美元/加仑.其中,每吨生物质约44美元.因此,目前乙醇掺汽油具有十分强的市场竞争力.已有几个公司正在建造首批商业纤维素乙醇工厂,虽然这些刚起步的小型设施在合理利用和管理上风险较小,但规模经济需要较大型工厂.尽管配送生物质原料的成本会随需求的增加而增加,但在乙醇生产基础上的生物精炼技术的发展,尤其是化工产品和动力的协同生产,将会使全过程的经济可行性大大提高.进一步深入的基础研究,将解决低成本下实现纤维素的完全利用,以确保在无政策性补贴的前提下,真正使纤维素乙醇成为具有市场竞争力的低成本纯液体燃料. 相似文献
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Hierarchically porous architecture of ir on-nitroge n-carb on(Fe-N-C)for oxyge n reducti on reaction(ORR)is highly desired towards efficient mass transfer in the fuel cell device manner.Herein,we reported a binary ligand strategy to prepare zeolitic imidazolate frameworks(ZIFs)-derived precursors,wherein the addition of secondary ligand endows precursors with the capabilities to transform into porously interweaved encapsulation-nanotubes structured composites after calcination.The optimal catalyst,i.e.,termed as Fe6-M/C-3,exhibits excellent durability with 88.8%current retention after 50,000 seconds in 0.1 M HClO4solution by virtue of nanoparticles-encapsulation features,which is more positive than the benchmark commercial 20 wt%Pt/C catalyst.Moreover,a promising maximum power density of Fe6-M/C-3 as cathode catalyst was also dem on strated in proton exchange membrane fuel cells(PEMFCs)measurements.Therefore,this binary ligand approach to the fabrication of hierarchically porous structures would also have significant implications for various other electrochemical reactions. 相似文献
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Nannan Li Wei Liu Chao Zhu Ce Hao Jingya Guo Hongyu Jing Jinwen Hu Cuncun Xin Danyang Wu Yantao Shi 《Journal of Energy Chemistry》2021,(3)
Currently,pyrolysis as the most widely used method still has some key issues not well resolved for synthesis of carbon-supported single-atom catalysts(C-SACs),e.g.,the sintering of metal atoms at high temperature as well as the high cost and complicated preparations of precursors.In this report,molten salts are demonstrated to be marvellous medium for preparation of C-SACs by pyrolysis of small molecular precursors(ionic liquid).The ultrastrong polarity on one hand establishes robust interaction with precursor and enables better carbonization,resulting in largely enhanced yield.On the other hand,the aggregation of metal atoms is effectively refrained while no nanoparticle or cluster is formed.By this strategy,a C-SAC with atomically dispersed Fe-N4 sites and a high specific area over 2000 m2 g-1 is obtained,which illustrates high ORR activity in both acid and alkaline media.Moreover,this SAC exhibits superior methanol tolerance and stability after acid soaking at 85℃ for 48 h.It is believed that the molten-salts-assisted pyrolysis can be developed into a routine strategy as it not only can largely simply the synthesis of C-SACs,but also can be extended to prepare other types of SACs. 相似文献
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镧对Mg-Si合金中Mg2Si相变质的影响 总被引:1,自引:0,他引:1
研究了Mg-5Si合金中La的添加对初生Mg2Si相变质的影响。结果表明,适量的La能够有效地变质初生Mg2Si相。基于本文的研究,在添加约0.5%La时,获得了最佳的变质效果,此时,初生Mg2Si相的尺寸减小到25μm以下,其形态从粗大的树枝形状变为多面体形状。然而,当La增加到0.8%或者更高时,初生Mg2Si相又生长为粗大的树枝形态。而且,在凝固过程中发现形成了一些LaSi2化合物,这些化合物的数量随着La的增加而呈现逐渐增加的趋势。 相似文献
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建立STD/KED模式-电感耦合等离子体质谱(ICP-MS)法同时测定天然水体中铍、硼、钛、钒、铬、锰、钴、镍、铜、锌、钼、镉、锑、钡、铊、铅、铁、砷和硒19种元素的分析方法。仪器调谐校准后,样品在线加入锂、钪、铑、铋校准溶液校正,以标准曲线内标法定量分析。标准曲线相关系数均大于0.999,样品加标回收率为92.6%~103.6%,质控样品测定值相对标准偏差为0.20%~2.6%(n=6),方法检出限为0.01~0.70μg/L。该方法灵敏度高,操作简便,节省人力,能满足天然水体中19种元素的同时检测需要。 相似文献
8.
电解质-非电解质混合溶液活度系数的关联及溶解的推算 II:NH3-NaCl-Na2SO4-H2O体系的液固平衡热力学 总被引:1,自引:0,他引:1
由于在研究的体系中, Na2SO4是非对称电解质, 且能生成水合盐, 故推导了由非对称型电解质与非电解质所构成的混合溶液的各组分的活度系数关联通式, 并在此基础上讨论了水合盐液固平衡的计算方法. 相似文献
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在室温条件下,以甲基丙烯酸环氧丙酯(GMA)为单体,溴异丁酰溴为引发剂,CuCl/2,2′-联吡啶(Bpy)为催化剂,通过原子转移自由基聚合(ATRP)反应,将甲基丙烯酸环氧丙酯聚合在硅胶表面。然后再将L-苯丙氨酸共价键合在硅胶表面的聚合物上,制备了新型手性配体交换色谱固定相,并用该固定相对DL-氨基酸进行分离。用元素分析对其进行了表征;详细考察了固定相的合成过程以及流动相pH值、流动相铜离子浓度、柱温等色谱条件对DL-氨基酸对映体拆分的影响。元素分析得出该固定相表面L-苯丙氨酸接枝密度达到4.32 mg/m2;在手性配体交换分离模式下,流动相为0.05 mol/L KH2PO4-0.1 mmol/L Cu(Ac)2水溶液、流速为1.0 mL/min、柱温为50 ℃和检测波长为223 nm条件下,该色谱固定相可以分离DL-天冬氨酸、DL-天冬酰胺等。同时,流动相pH值、铜离子浓度以及柱温对手性对映体的拆分有较大影响。与传统的在硅胶表面直接键合L-苯丙氨酸制得的固定相相比,所合成的固定相接枝密度高,分离效果好,对DL-天冬氨酸及DL-天冬酰胺实现了基线分离。结果表明,在手性配体交换分离模式下,固定相具有良好的拆分性能。 相似文献
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Philip L. Wylie Richard J. Phillips Kenneth J. Klein Michael Q. Thompson Bruce W. Hermann 《Journal of separation science》1991,14(10):649-655
An experimental injection port has been designed for split or splitless sample introduction in capillary gas chromatography; the inlet uses electronic pressure control, in order that the column head pressure may be set from the GC keyboard, and the inlet may be used in the constant flow or constant pressure modes. Alternatively, the column head pressure may be programmed up or down during a GC run in a manner analogous to even temperature programming. Using electronic pressure control, a method was developed which used high column head pressures (high column flow rates) at the time of injection, followed by rapid reduction of the pressure to that required for optimum GC separation. In this way, high flow rates could be used at the time of splitless injection to reduce sample discrimination, while lower flow rates could be used for the separation. Using this method, up to 5 μl of a test sample could be injected in the splitless mode with no discrimination; in another experiment, 2.3 times as much sample was introduced into the column by using electronic pressure programming. Some GC peak broadening was observed in the first experiment. 相似文献
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设计合成了新的噻吩杂环衍生化β-环糊精手性固定相2,6-二-O-戊基-3-O-[(2-甲酰基)-噻吩基]-β-CD, 研究了色谱分离性能. 结果表明, 该固定相对各类有机化合物, 特别是芳香族位置异构体及对映异构体有较好的分离能力, 并对含多手性中心的菊酸衍生物具有一定的分离效果, 显示了较强的立体选择能力. 相似文献
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Optimization of the coupling of high-temperature liquid chromatography and flame ionization detection application to the separations of alcohols 总被引:2,自引:0,他引:2
Guillarme D Heinisch S Gauvrit JY Lanteri P Rocca JL 《Journal of chromatography. A》2005,1078(1-2):22-27
The feasibility of coupling high-temperature liquid chromatography (HTLC) to flame ionization detection (FID) has been studied. FID parameter values (hydrogen flow-rate, air flow-rate and FID temperature), typically set in gas chromatography are rarely suitable for liquid chromatography. Best values depend obviously on the water flow rate which is defined depending on both column temperature and column internal diameter. The FID parameters were optimized according to the water flow-rate by means of an experimental design. The potential of the method is shown with some alcohol separations and the value of increasing column temperature while reducing the column diameter is highlighted. 相似文献
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《Journal of separation science》2018,41(4):893-898
We report the fabrication and performance of a silicon‐on‐glass micro gas chromatography eight‐capillary column based on microelectromechanical systems technology that is 50 cm long, 30 μm wide, and 300 μm deep. According to the theory of a gas chromatography column, an even gas flow among different capillaries play a vital role in the peak broadening. Thus, a flow splitter structure is designed by the finite element method through the comparison of the velocity distributions of the eight‐capillary columns with and without splitter as well as an open tubular column. The simulation results reveal that eight‐capillary column with flow splitters can receive more uniform flow velocity in different capillaries, hence decreases the peak broadening and in turn increases the separation efficiency. The separation experiment results show that the separation efficiency of about 22 000 plates/m is achieved with the chip column temperature programmed for analysis of odorous sulfur pollutants. This figure is nearly two times higher than that of the commercial capillary column coated the similar stationary phase. And the separation time of all the components in the microcolumn is less than 3.8 min, which is faster than the commercial capillary column. 相似文献
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The congener-specific analysis of polychlorinated biphenyls (PCB) by high resolution gas chromatography on a 50 m × 0.25 mm fused silica column coated with a 0.26 μm film of 5% diphenyl polydimethylsiloxane (CPSil-8) has been significantly improved by series coupling with a 25 m × 0.22 mm column coated with a 0.10 μm film of 1,2-dicarba-closo-dodecarborane polydimethylsiloxane (HT-5). Using helium as carrier gas, a total of 64 congeners in technical PCB mixtures could be analyzed as resolved peaks by ECD (86 by MS) with the CPSil-8 column, and 84 by ECD (108 by MS) with the combination. The high upper temperature limit for these stationary phases (>300°C) enabled fast temperature programming and rapid analysis (60 min). 相似文献
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Summary Effects of column temperature on the retention behaviour of aromatic hydrocarbons and dialkyl phthalates were investigated in capillary supercritical fluid chromatography (SFC) with carbon dioxide as the mobile phase. Negative temperature programming could partly replace pressure programming. Positive temperature programming was applicable to solutes with proper volatility, in which gas chromatography-like retention mechanism (partition process) was involved. 相似文献