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1. chinaXiv:201708.00223 [pdf]

Laser irradiation-induced Au-ZnO nanospheres with enhanced sensitivity and stability in ethanol sensing

张豪
分类: 物理学 >> 普通物理:统计和量子力学,量子信息等

Incorporating noble metal nanoparticles on the surface or inner side of semiconductors to form a hybrid nanostructure is an effective route to improve the gas sensing performance of these semiconductors. In this study, we present novel Au-decorated ZnO nanospheres (Au-ZnO NSs) obtained by laser irradiation of liquids. Structural characterization indicated that the Au-ZnO NSs consisted of single crystalline ZnO NSs with few Au nanoparticles decorated on their surfaces and abundant encapsulated Au nanoparticles with relatively small sizes. Laser irradiation-induced heating–melting–evaporating processes are responsible for the formation of unique Au-ZnO NSs. Gas sensing properties of the Au-ZnO NSs, as gas sensing materials, were investigated and compared with those of pure ZnO NSs. The former showed lower working temperature, higher sensitivity, better selectivity, and good reproducibility. The response values of Au-ZnO NSs and pure ZnO NSs sensors to ethanol of 100 ppm were 252 and 75 at working temperature of 320 °C and 360 °C, respectively. The significant enhancements in gas sensing performance should be attributed to the electronic sensitization induced by the depleted layers between encapsulated Au nanoparticles and ZnO and chemical sensitization originating from the catalytic effects of Au nanoparticles decorated on the surfaces that dissociated molecular oxygen.

提交时间: 2017年08月18日 点击量:32, 下载量:21

2. chinaXiv:201708.00219 [pdf]

Monodispersed Carbon Nanodots Spontaneously Separated from Combustion Soot with Excitation.pdf

张豪
分类: 物理学 >> 普通物理:统计和量子力学,量子信息等

We present a facile, low-cost procedure by simple one-step combustion of small organic molecules to obtain ultrafine, hydrophobic, and fluorescent carbon nanodots (CNDs). Without further centrifugation and dialysis, we could easily separate CNDs from combustion soot through spontaneous sedimentation. Transmission electron microscopy and photoluminescence characterization demonstrated that the collected CNDs possessed a monodispersed size distribution with a diameter of 1.9 ± 0.5 nm and excitation-independent luminescent properties. Furthermore, after oxidization treatment, the oxidized CNDs displayed good water solubility and the highest fluorescent intensity at neutral solution.

提交时间: 2017年08月16日 点击量:45, 下载量:30

3. chinaXiv:201708.00217 [pdf]

Photo-excited in situ loading of Pt clusters onto rGO immobilized SnO2 with excellent catalytic performance toward methanol oxidation

吴守良
分类: 物理学 >> 普通物理:统计和量子力学,量子信息等

Great effort is made to maximize the surface area and expose active sites of a catalyst by distributing it over a suitable electronic conducting support. We present a design and eco-friendly construction of a two-dimensional Pt/SnO2/reduced-graphene-oxide (rGO) nanocomposite to study the strong metal-semiconductor-support interactions as candidate highly active and durable electrocatalyst. Distinctively, highly reactive SnOx nanoparticles (NPs) induced by laser ablation in liquids were used as a precursor to transform the graphene oxide (GO). Simultaneously, the initial amorphous-like SnOx further crystallized into SnO2 NPs, which were uniformly anchored onto rGO sheets. Afterward, the photo-excited electrons from semiconductor SnO2 were used as green reducing agents. Ultrafine Pt NPs with an average size of about 1–2 nm were in situ reduced and uniformly anchored on the surface of crystallized SnO2 NPs. Compared with the Pt/rGO catalysts without SnO2 modification, the prepared Pt/SnO2/rGO catalysts not only show larger electrochemical active surface area and higher catalytic activity toward methanol oxidation but also exhibit better tolerance toward CO and long-term cycle stability. The significantly enhanced electrochemical performance should be attributed to the uniformly dispersed Pt NPs with ultrafine size and the synergetic effect from the hybrid noble metal-semiconductor-carbon network components, which possess promising potential applications as electrocatalysts for methanol oxidation.

提交时间: 2017年08月15日 点击量:46, 下载量:31

4. chinaXiv:201708.00216 [pdf]

开放获取期刊权益政策调研分析

刘静羽; 黄金霞; 王昉
分类: 图书馆学、情报学 >> 图书馆学

通过对20家开放获取期刊出版社网站信息的调研,梳理出与开放获取期刊再利用有关的权益信息,并进一步归纳出当前OA期刊权益政策的三种主要类型,包括开放获取政策、网站使用政策、批量数据获取政策,以及分析了政策内容对图书馆开放获取期刊建设带来的影响和图书馆可采取的对策。

提交时间: 2017年08月15日 点击量:52, 下载量:47

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