Institutional Repository of Dalian Institute of Chemical Physics, CAS
Not a member yet
45557 research outputs found
Sort by
Open Foundation of the State Key Laboratory of Bioactive Seaweed Substances[SKL-BASS1711]
No full text
Manganese(I)-Catalyzed Synthesis of Fused Eight- and Four-Membered Carbocycles via C-H Activation and Pericyclic Reactions
No full textPericyclic reactions have allowed facile construction of complex cycles. On the other hand, metal-catalyzed C-H activation has been established as an important strategy for rapid synthesis of complex structures. The two areas are integrated in Mn(I)-catalyzed redox-neutral coupling of 3-alkenyl- and 3-allylindoles with propargylic carbonates, which occurred via C-H allenylation with subsequent pericyclic reactions to afford fused eight- and four-membered carbocycles, respectively
Ultrahigh-Content Nitrogen-doped Carbon Encapsulating Cobalt NPs as Catalyst for Oxidative Esterification of Furfural
No full textIt is an attractive and challenging topic to endow non-noble metal catalysts with high efficiency via a nitrogen-doping approach. In this study, a nitrogen-doped carbon catalyst with high nitrogen content encapsulating cobalt NPs (CoOx@N-C(g)) was synthesized, and characterized in detail by XRD, HRTEM, N-2-physisorption, ICP, CO2-TPD, and XPS techniques. g-C3N4 nanosheets act as nitrogen source and self-sacrificing templates, giving rise to an ultrahigh nitrogen content of 14.0%, much higher than those using bulk g-C3N4 (4.4%) via the same synthesis procedures. As a result, CoOx@N-C(g) exhibited the highest performance in the oxidative esterification of biomass-derived platform furfural to methylfuroate under base-free conditions, achieving 95.0% conversion and 97.1% selectivity toward methylfuroate under 0.5MPa O-2 at 100 degrees C for 6h, far exceeding those of other cobalt-based catalysts. The high efficiency of CoOx@N-C(g) was closely related to its high ratio of pyridinic nitrogen species that may act as Lewis basic sites as well as its capacity for the activation of dioxygen to superoxide radical O-2(.-)
The Influence of Sodium Iodide Salt on the Interfacial Properties of Aqueous Methanol Solution by a Combined Molecular Simulation and Sum Frequency Generation Vibrational Spectroscopy Study
No full textUnderstanding the influence of salt ions on the microscopic properties of liquid interfaces is of both fundamental and practical importance. A large number of previous experimental and theoretical investigations have explored the salt effects on the surfaces of either pure water or neat organic liquid. However, how the salt ions affect the interfacial structures of water/organic liquid mixtures has rarely been studied. Here, the molecular dynamics (MD) simulations and sum frequency generation vibrational spectroscopy (SFG-VS) were carried out to investigate the influence of sodium iodide (NaI) on the air/liquid interfaces of the methanol-water mixtures. The SFG-VS spectral intensities were discovered to increase with the addition of 3 M NgI while the center frequencies of the C-H stretching vibrations at high methanol concentrations showed a similar to 2 cm(-1) blue shift compared with those obtained before adding NaI. The MD results indicated that Na+ and I- can only affect Part I (near the bulk phase) but not Part II (near the gas phase) of the interfacial region. It was also found that the average orientations of interfacial methyl groups were constant and not effectively disturbed by the changes of methanol concentrations or the addition of NaI. It is therefore concluded that the changes of the SFG-VS intensities upon the addition of NaI salts were mainly caused by the increasing number of interfacial methanol molecules. Further analysis showed that the existence of NaI affects the surface tensions more for the interfaces with higher bulk methanol concentrations, which is in agreement with the SFG-VS results. It is noteworthy that the maximum number density of methanol molecules with the net nonzero orientations is reached near the Gibbs dividing surface, the reasons of which are worth further investigating
Cr-doped alpha-MoO3 nanorods for the fast detection of triethylamine using a pulse-heating strategy
No full textTriethylamine (TEA), a high-molecular amine, has a terrible desorption rate on oxide surfaces, and it remains a challenge to develop a rapid response sensor to detect it. Herein, Cr-doped alpha-MoO3 nanorods have been prepared through a grinding and subsequent annealing route. The microstructure of the as-obtained Cr-doped alpha-MoO3 nanorods was determined using various analysis techniques. Sensing experiments showed that the Cr-doped alpha-MoO3 nanorods exhibit a significant response for TEA, with actual concentrations as low as 1 ppm at 200 degrees C. Moreover, the sensor can be completely recovered after a TEA-sensing event in less than 2 min using pulse-heating at 300 degrees C in air. In addition, an ultrahigh selectivity for TEA against other vapors was observed. This doping method, combined with a pulse-heating technique, may act as an efficient strategy for designing a high-performance gas sensor. (C) 2019 Elsevier B.V. All rights reserved
Waveform control in generations of intense water window attosecond pulses via multi-color combined field
No full textThe waveform control in the improvements of high-order harmonic generation (HHG) spectra and attosecond pulse signals driven by the two-color and three-color combined fields has been theoretically investigated. (a) The results show that by properly controlling the omega-2 omega two-color laser beam (including the modulations of chirps, carrier envelope phases and delay time), either the harmonic cutoff can be extended, showing a water window spectral continuum, or the selective enhancement of the single-order and two-order harmonics can be found. Further, with the introduction of a third controlling field, the efficiency of spectral continuum can be enhanced by two orders of magnitude compared with that from the two-color field. Moreover, the enhancement of HHG is not very sensitive to the frequency of the third field (i.e., the frequency of the third field is chosen to be 3 omega, 4 omega and 6 omega). Thus, some water window attosecond pulses with the durations of 60 as can be obtained. (b) Furthermore, the harmonic cutoff can be further extended when using a half-cycle controlling pulse or introducing the inhomogeneous effect of the laser field. Moreover, the efficiency of HHG can be further improved when the initial state is prepared as the superposition state of the ground state and some excited state of He atom. Consequently, a much broader spectral continuum with an intensity enhancement of another two orders of magnitude can be found. Finally, through the Fourier transformation of some spectral continuum, the intense water window attosecond pulses with the durations of 60 as can be produced
Effect of Near-Surface Dopants on the Epitaxial Growth of h-BN on Metal Surfaces
No full textEpitaxial growth of ultrathin overlayers on solid substrate is critically dependent on the surface structure, and in this work near-surface doping is identified as another important growth factor. It is shown that growth of hexagonal boron nitride (h-BN) on Ni(111) through chemical vapor deposition or surface ammonization can be strongly modulated by near-surface B doping. Epitaxial h-BN islands form on clean Ni(111) surface, while both epitaxial and nonepitaxial h-BN islands grow on Ni(111) containing near-surface B atoms. Quantitative correlation of epitaxial growth and near-surface doping is unambiguously demonstrated. In situ spatially resolved surface science measurements based on photoemission electron microscopy and low energy electron microscopy in combination with density function calculations reveal that near-surface B atoms weaken the interaction between h-BN overlayer and Ni surface, which favor the nonepitaxial and metastable h-BN structures. The present work suggests that near-surface doping acts as an effective route to influence epitaxial growth of two-dimensional (2D) material overlayers on solids