Shanghai University

About: Shanghai University is a education organization based out in Shanghai, Shanghai, China. It is known for research contribution in the topics: Microstructure & Catalysis. The organization has 59583 authors who have published 56840 publications receiving 753549 citations. The organization is also known as: Shànghǎi Dàxué.

Full-color fluorescent carbon quantum dots

Abstract: Quantum dots have innate advantages as the key component of optoelectronic devices. For white light-emitting diodes (WLEDs), the modulation of the spectrum and color of the device often involves various quantum dots of different emission wavelengths. Here, we fabricate a series of carbon quantum dots (CQDs) through a scalable acid reagent engineering strategy. The growing electron-withdrawing groups on the surface of CQDs that originated from acid reagents boost their photoluminescence wavelength red shift and raise their particle sizes, elucidating the quantum size effect. These CQDs emit bright and remarkably stable full-color fluorescence ranging from blue to red light and even white light. Full-color emissive polymer films and all types of high-color rendering index WLEDs are synthesized by mixing multiple kinds of CQDs in appropriate ratios. The universal electron-donating/withdrawing group engineering approach for synthesizing tunable emissive CQDs will facilitate the progress of carbon-based luminescent materials for manufacturing forward-looking films and devices.

Emission inventory of anthropogenic air pollutants and VOC species in the Yangtze River Delta region, China

Abstract: . The purpose of this study is to develop an emission inventory for major anthropogenic air pollutants and VOC species in the Yangtze River Delta (YRD) region for the year 2007. A "bottom-up" methodology was adopted to compile the inventory based on major emission sources in the sixteen cities of this region. Results show that the emissions of SO2, NOx, CO, PM10, PM2.5, VOCs, and NH3 in the YRD region for the year 2007 are 2392 kt, 2293 kt, 6697 kt, 3116 kt, 1511 kt, 2767 kt, and 459 kt, respectively. Ethylene, mp-xylene, o-xylene, toluene, 1,2,4-trimethylbenzene, 2,4-dimethylpentane, ethyl benzene, propylene, 1-pentene, and isoprene are the key species contributing 77 % to the total ozone formation potential (OFP). The spatial distribution of the emissions shows the emissions and OFPs are mainly concentrated in the urban and industrial areas along the Yangtze River and around Hangzhou Bay. The industrial sources, including power plants other fuel combustion facilities, and non-combustion processes contribute about 97 %, 86 %, 89 %, 91 %, and 69 % of the total SO2, NOx, PM10, PM2.5, and VOC emissions. Vehicles take up 12.3 % and 12.4 % of the NOx and VOC emissions, respectively. Regarding OFPs, the chemical industry, domestic use of paint & printing, and gasoline vehicles contribute 38 %, 24 %, and 12 % to the ozone formation in the YRD region.

Large-scale highly ordered Sb nanorod array anodes with high capacity and rate capability for sodium-ion batteries

Abstract: Na-ion batteries are a potential substitute to Li-ion batteries for energy storage devices. However, their poor electrochemical performance, especially capacity and rate capability, is the major bottleneck to future development. Here we propose a performance-oriented electrode structure, which is 1D nanostructure arrays with large-scale high ordering, good vertical alignment, and large interval spacing. Benefiting from these structural merits, a great enhancement in electrochemical performance could be achieved. Taking Sb as an example, we firstly report large-scale highly ordered Sb nanorod arrays with uniform large interval spacing (190 nm). In return for this electrode design, high ion accessibility, fast electron transport, and strong electrode integrity are presented here. Used as additive- and binder-free anodes for Na-ion batteries, Sb nanorod arrays showed a high capacity of 620 mA h g−1 at the 100th cycle with a retention of 84% up to 250 cycles at 0.2 A g−1, and a superior rate capability for delivering reversible capacities of 579.7 and 557.7 mA h g−1 at 10 and 20 A g−1, respectively. A full cell coupled by a P2-Na2/3Ni1/3Mn2/3O2 cathode and a Sb nanorod array anode was also constructed, which showed good cycle performance up to 250 cycles, high rate capability up to 20 A g−1, and large energy density up to 130 Wh kg−1. These excellent electrochemical performances shall pave the way for developing more applications of Sb nanorod arrays in energy storage devices.

Recent progress in the phase-transition mechanism and modulation of vanadium dioxide materials

Abstract: Metal-to-insulator transition (MIT) behaviors accompanied by a rapid reversible phase transition in vanadium dioxide (VO2) have gained substantial attention for investigations into various potential applications and obtaining good materials to study strongly correlated electronic behaviors in transition metal oxides (TMOs). Although its phase-transition mechanism is still controversial, during the past few decades, people have made great efforts in understanding the MIT mechanism, which could also benefit the investigation of MIT modulation. This review summarizes the recent progress in the phase-transition mechanism and modulation of VO2 materials. A representative understanding on the phase-transition mechanism, such as the lattice distortion and electron correlations, are discussed. Based on the research of the phase-transition mechanism, modulation methods, such as element doping, electric field (current and gating), and tensile/compression strain, as well as employing lasers, are summarized for comparison. Finally, discussions on future trends and perspectives are also provided. This review gives a comprehensive understanding of the mechanism of MIT behaviors and the phase-transition modulations. Smart coatings that alter their electrical properties on demand can be created from shape-shifting vanadium dioxide (VO2) crystals. Xun Cao from Shanghai Institute of Ceramics, Chinese Academy of Sciences in Shanghai and co-workers review efforts to understand the mechanisms that enable VO2 to rapidly switch between two crystal states — one with metallic conductivity, the other insulating—at near-room temperature conditions. Theoretical calculations and nanoscale experiments reveal that VO2 transitions are triggered by a combination of interactions between electrons and atoms in the crystal lattice, and through forces that cause electrons to avoid each other. Several innovative methods of manipulating the VO2 switching temperature have emerged including foreign element additions, laser irradiation, and controlled substrate bending. The sensitivity of VO2 transitions to mechanical stress has inspired proposals for ultrafast response breath sensors and artificial skin. In this article, we review the prototypical phase-transition material-VO2, which undergoes structure and conductivity changes simultaneously. The recent progresses in the transition mechanism are also discussed. Besides, this work gives a comprehensive understanding of the phase-transition modulations, such as element doping, electric field (current and gating) and tensile/compression strain, as well as employing laser.