Co-reporter:S. C. Ouyang, L. W. Wang, X. W. Du, C. Zhang and J. Yang
RSC Advances 2016 vol. 6(Issue 55) pp:49777-49781
Publication Date(Web):05 May 2016
DOI:10.1039/C6RA04681A
Noble metal nanoclusters are highly desirable for achieving superior catalytic performance in diverse catalytic reactions. However, they usual suffer from fast surface oxidation before use, which substantially degrades their activities. Herein, we address, for the first time, an in situ preparation strategy towards well-dispersed, ligand-free Pt nanoclusters (1.28 nm) supported on carbon spheres (CS) for high-temperature catalytic reactions. The nanoclusters are formed through thermal decomposition of platinum(II) acetylacetonate concomitantly with the preheating of the reactor and directly serve as catalysts for the dehydrogenation of methylcyclohexane (MCH) without deoxidization pretreatment. Nearly 97% of MCH is converted to hydrogen and toluene over the 0.68 wt% Pt/CS catalyst at 320 °C, and the highest hydrogen evolution rate reaches a value of 575 mmol gmet−1 min−1. Besides, the reaction equilibrium is achieved much faster than using catalysts prepared ex situ that require deoxidization of Pt species by hydrogen generated during the initial stage of the reaction.
Co-reporter:Shu-Tao Song, Lan Cui, Jing Yang, and Xi-Wen Du
ACS Applied Materials & Interfaces 2015 Volume 7(Issue 3) pp:1949
Publication Date(Web):January 8, 2015
DOI:10.1021/am508750y
As a promising material for photoelectrical application, MoS2 has attracted extensive attention on its facile synthesis and unique properties. Herein, we explored a novel strategy of laser ablation to synthesize MoS2 fullerene-like nanoparticles (FL-NPs) with stable photoresponse under high temperature. Specifically, we employed a millisecond pulsed laser to ablate the molybdenum target in dimethyl trisulfide gas, and as a result, the molybdenum nanodroplets were ejected from the target and interacted with the highly reactive ambient gas to produce MoS2 FL-NPs. In contrast, the laser ablation in liquid could only produce core–shell nanoparticles. The crucial factors for controlling final nanostructures were found to be laser intensity, cooling rate, and gas reactivity. Finally, the MoS2 FL-NPs were assembled into a simple photoresponse device which exhibited excellent thermal stability, indicating their great potentialities for high-temperature photoelectrical applications.Keywords: laser ablation; MoS2 nanoparticles; photoresponse
Co-reporter:Rui-Chun Luo;Chao Li; Xi-Wen Du ; Jing Yang
Angewandte Chemie International Edition 2015 Volume 54( Issue 16) pp:4787-4791
Publication Date(Web):
DOI:10.1002/anie.201411322
Abstract
Monodisperse non-noble metal nanocrystals (NCs) that are highly uniform in shapes and particle size are much desired in various advanced applications, and are commonly prepared by either thermal decomposition or reduction, where reactive organometallic precursors or/and strong reducing agents are mandatory; however, these are usually toxic, costly, or suffer a lack of availability. Bulk Group 12 metals can now be converted into ligand-protected, highly crystalline, monodisperse spherical metal NCs with precisely controlled sizes without using any precursors and reducers. The method is based on low-power NIR-laser-induced size-selective layer-by-layer surface vaporization. The monodisperse Cd NCs show pronounced deep-UV (DUV) localized surface plasmon resonance making them highly competitive DUV-plasmonic materials. This approach will promote appreciably the emergence of a wide range of monodisperse technically important non-coinage metal NCs with compelling functionalities.
Co-reporter:Rui-Chun Luo;Chao Li; Xi-Wen Du ; Jing Yang
Angewandte Chemie 2015 Volume 127( Issue 16) pp:4869-4873
Publication Date(Web):
DOI:10.1002/ange.201411322
Abstract
Monodisperse non-noble metal nanocrystals (NCs) that are highly uniform in shapes and particle size are much desired in various advanced applications, and are commonly prepared by either thermal decomposition or reduction, where reactive organometallic precursors or/and strong reducing agents are mandatory; however, these are usually toxic, costly, or suffer a lack of availability. Bulk Group 12 metals can now be converted into ligand-protected, highly crystalline, monodisperse spherical metal NCs with precisely controlled sizes without using any precursors and reducers. The method is based on low-power NIR-laser-induced size-selective layer-by-layer surface vaporization. The monodisperse Cd NCs show pronounced deep-UV (DUV) localized surface plasmon resonance making them highly competitive DUV-plasmonic materials. This approach will promote appreciably the emergence of a wide range of monodisperse technically important non-coinage metal NCs with compelling functionalities.
Co-reporter:Wen-Tian Wu, Hui Liu, Chao Dong, Wen-Jing Zheng, Li-Li Han, Lan Li, Shi-Zhang Qiao, Jing Yang, and Xi-Wen Du
Langmuir 2015 Volume 31(Issue 8) pp:2251-2255
Publication Date(Web):February 17, 2015
DOI:10.1021/la5044415
Green and simple synthesis of high-quality colloidal quantum dots (CQDs) is of great importance and highly anticipated yet not fully implemented. Herein, we achieve the direct conversion of natural minerals to highly uniform, crystalline lead sulfide CQDs based on laser irradiation in liquid. The trivial fragmentation of mineral particles by an intense nanosecond laser was found to create a localized high degree of monomer supersaturation in oleic acid, initiating the LaMer growth of uniform CQDs. The photoconductive device made of these CQDs exhibits a competitive temporal response of photocurrent with those highly sensitive photodetectors based on PbS CQDs reported in the literature. Our synthesis strategy paves the way for the most environmentally friendly and convenient mass production of high-quality uniform CQDs.
Co-reporter:Hongli Wang 王洪礼;Zhipei Zhao 赵志培;Jing Sun 孙 景
Transactions of Tianjin University 2013 Volume 19( Issue 1) pp:66-69
Publication Date(Web):2013 February
DOI:10.1007/s12209-013-1770-9
Laser plays an important role in synthesizing nanometer material. A three-dimensional mathematical model is established in this paper when single pulsed millisecond laser shocks the surface of the metal target at a liquid-solid interface. By changing laser power density and target size, the temperature field variation of the metal target is investigated. Results show that the generation process of nanoparticles includes heating, melting and boiloff.
Co-reporter:Wen-Jing Qin, Jing Sun, Jing Yang, Xi-Wen Du
Materials Chemistry and Physics 2011 Volume 130(1–2) pp:425-430
Publication Date(Web):17 October 2011
DOI:10.1016/j.matchemphys.2011.07.001
Cu doping of ZnO quantum dots (QDs) was carried out by laser ablation of Zn/Cu composite targets immersed in PVP aqueous solution. Zn/Cu core–shell particles were firstly prepared by a galvanic replacement reaction, and then they were pressed into targets with different Zn/Cu ratios for laser ablation. Under the extremely non-equilibrium conditions generated by the pulse laser used, a large amount of Cu-doped ZnO QDs were produced with ultrafine size, good dispersibility, and high stability. On the other hand, the dopant concentration was feasibly controlled from 1.8% to 4.8% by changing the atomic content of Cu in Zn/Cu composite targets. Cu-doped QDs exhibited blue emission with tunable wavelength, which was ascribed to electronic transitions from the conductor band of ZnO to the acceptor levels related to Cu dopants. As a facile and versatile technique, laser ablation is believed to be an effective way for fabricating various doped nanocrystals.Highlights► Cu-doped ZnO quantum dots synthesized by laser ablation in PVP aqueous solution. ► The Cu-doped ZnO QDs have ultrafine size, good dispersibility, and high stability. ► We control the doping extent by changing the atomic ratio in Zn/Cu composite targets. ► The Cu-doped ZnO QDs exhibit blue emission with tunable wavelength. ► Laser ablation presents an effective method for obtaining various doped nanocrystals.
Co-reporter:Kui-Ming Lv, Jing Yang, Kai-Yang Niu, Hong-Li Wang, Jing Sun, Xi-Wen Du
Materials Letters 2009 Volume 63(Issue 28) pp:2492-2494
Publication Date(Web):30 November 2009
DOI:10.1016/j.matlet.2009.08.049
Controllable synthesis of Si–C nanostructures was realized in a laser ablation system by adopting solid silicon target and n-heptane vapor as starting materials. Ultrafine SiC nanocrystals and graphite-coated SiC nanocrystals were synthesized with the laser frequency of 1 Hz and 20 Hz, respectively. According to the real-time observation on the plasma evolvement, we proposed a formation mechanism of Si–C nanostructure related to vapor-phase reaction. Our method can be extended to other material systems for diverse novel nanostructures.
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