Graphene Quantum Dots Enhanced Electrochemical Performance of Polypyrrole as Supercapacitor Electrode

通过将吡咯单体在低温下与石墨烯量子点进行原位聚合，获得一种全新的聚吡咯/石墨烯量子点（PPY/GQD）复合材料. 实验中采用了扫描电子显微镜（SEM）、原子力显微镜（AFM）、X射线衍射(XRD)、红外（FT-IR）和热重（TGA）对复合物的表面形貌、结构进行表征. 结果表明，吡咯单体以石墨烯量子点为软模板，以化学键的方式在石墨烯量子点的表面聚合生长成片状聚吡咯. 通过机械冷压法将粉末状PPY/GQD复合物压成圆片电极，电极的电化学测试结果表明，PPY和GQD质量比为50:1所制得的复合物的电容量为485 F·g-1，同时在两千次循环之后电容量只降低了大约2%. 通过与同比例的PG（聚吡咯/石墨烯复合材料）以及纯PPY对比，发现聚吡咯/石墨烯量子点的高比容量及优异的循环稳定性将会使其在电化学超级电容器领域中具有的潜在的应用价值.With an objective to develop electrode materials with high specific capacitance and good stability, a completely new nanocomposite of Polypyrrole (PPY) and graphene quantum dots (GQD) was successfully obtained through in-situ polymerization of pyrrole in the presence of GQD suspension. The obtained composites with different mass ratios were characterized by X-Ray diffraction (XRD), Fourier transformed infrared spectroscopy (FT-IR) and scanning electron microscopy (SEM). GQD enhanced electrochemical performance of PPY and, as supercapacitor electrodes, the PPY/GQD composites with the mass ratio of PPY to GQD at 50:1 showed a competitive specific capacitance of 485 F·g-1 at a scan rate of 0.005 V·s-1. The attenuation of the specific capacitance is about 2% after 2000 cycles. The high specific capacitance and good stability of the PPY/GQD nanocomposites are promising for applications in electrochemical supercapacitors.This work was supported by the National Natural Science Foundation of China (No. 20906055), National “973 Program” (No. 2010CB933900), and the State Key Laboratory of Bioreactor Engineering (No. 2060204).This work was supported by the National Natural Science Foundation of China (No. 20906055), National “973 Program” (No. 2010CB933900), and the State Key Laboratory of Bioreactor Engineering (No. 2060204).作者联系地址：上海交通大学微纳科学技术研究院，上海 200240Author's Address: Key Laboratory for Thin Film and Microfabrication of the Ministry of Education, Research Institute of Micro/Nano Science and Technology, Shanghai Jiao Tong University, Shanghai 200240, China通讯作者E-mail：[email protected]

Electrochemical Performances of Layered Polypyrrole/Chemically Reduced Graphene Oxide Nanocomposites as Supercapacitor Electrodes

论文通过将吡咯单体在低温下与氧化石墨烯进行原位聚合，获得聚吡咯/石墨烯（Ppy/CRGO）复合材料. 采用场发射电子显微镜（FESEM）、红外 (FT-IR)和热重 (TGA)对复合物的表面形貌、结构进行表征. FESEM结果表明，通过控制氧化石墨烯（GO）和吡咯单体的质量比例，可以对复合物的层状和厚度进行调控. FT-IR和TGA结果表明聚吡咯（Ppy）是通过化学键合的方式与氧化石墨烯复合在一起。通过机械冷压法将粉末状Ppy/CRGO复合物压成圆片电极，并探讨了石墨烯和聚吡咯复合比例、反应时间、烘干温度、孔隙率等因素对Ppy/CRGO复合物电极的电学和电化学性能的影响. 结果表明，Ppy与CRGO质量比为10:1所制得的Ppy/CRGO复合物的电容量为421 F?g-1，通过在电极中引入孔隙，电容量能进一步提升为509 F?g-1.Nanocomposites of polypyrrole (Ppy) and chemically reduced graphene oxide (CRGO), Ppy/CRGO, have been fabricated through in-situ polymerization of pyrrole on graphene oxide (GO) sheets. The as-synthesized Ppy/CRGO composites were characterized complementarily using scanning electron microscopy (SEM), thermogravimetric analysis (TGA), and Fourier transformed infrared spectroscopy (FT-IR). By controlling the initial ratio of the GO to pyrrole, the layered composites could be obtained and their thickness could be tuned properly. The Ppy/CRGO electrodes were prepared using a mechanical compressing technique and their electrical conductivity and electrochemical properties were characterized systematically. We demonstrated that as electrodes for supercapacitor, the Ppy/CRGO composites with Ppy to CRGO ratio of 10:1 showed a competitive capacitance of 421 F?g-1 that could be further increased to 509 F?g-1 by introducing pores in it, which is higher than that of Ppy alone. Given the manifest electrical and electrochemical properties, we envisage that the Ppy/CRGO composites should find applications in supercapacitors.This work was supported by the National Natural Science Foundation of China (No. 20906055), National “973 Program” (No. 2010CB933900) and the State Key Laboratory of Bioreactor engineering (No. 2060204).作者联系地址：上海交通大学微纳米科学与技术研究院，上海 200240Author's Address: National Key Laboratory of Micro/Nano Fabrication Technology, Key Laboratory for Thin Film and Microfabrication of the Ministry of Education, Research Institute of Micro/Nano Science and Technology, Shanghai Jiao Tong University, Shanghai 200240, China通讯作者E-mail：[email protected]

China's first step towards probing the expanding universe and the nature of gravity using a space borne gravitational wave antenna

In this perspective, we outline that a space borne gravitational wave detector network combining LISA and Taiji can be used to measure the Hubble constant with an uncertainty less than 0.5% in ten years, compared with the network of the ground based gravitational wave detectors which can measure the Hubble constant within a 2% uncertainty in the next five years by the standard siren method. Taiji is a Chinese space borne gravitational wave detection mission planned for launch in the early 2030 s. The pilot satellite mission Taiji-1 has been launched in August 2019 to verify the feasibility of Taiji. The results of a few technologies tested on Taiji-1 are presented in this paper. Gravitational wave astronomy has opened the door to test general relativity and the effect of gravity in the Universe. The authors present the capabilities of an overlap between space gravitational wave detectors LISA and Taiji to constrain the Hubble constant to 0.5%, in 10 years, and what can be learned from the satellite pilot Taiji-1 launched in 2019.</p

The first data release (DR1) of the LAMOST regular survey

The Large sky Area Multi-Object Fiber Spectroscopic Telescope (LAMOST) general survey is a spectroscopic survey that will eventually cover approximately half of the celestial sphere and collect 10 million spectra of stars, galaxies and QSOs. Objects in both the pilot survey and the first year regular survey are included in the LAMOST DR1. The pilot survey started in October 2011 and ended in June 2012, and the data have been released to the public as the LAMOST Pilot Data Release in August 2012. The regular survey started in September 2012, and completed its first year of operation in June 2013. The LAMOST DR1 includes a total of 1202 plates containing 2 955 336 spectra, of which 1 790 879 spectra have observed signal-to-noise ratio (SNR)&gt;= 1 0. All data with SNR &gt;= 2 are formally released as LAMOST DR1 under the LAMOST data policy. This data release contains a total of 2 204 696 spectra, of which 1 944 329 are stellar spectra, 12 082 are galaxy spectra and 5017 are quasars. The DR1 not only includes spectra, but also three stellar catalogs with measured parameters: late A, FGK-type stars with high quality spectra (1 061 918 entries), A-type stars (100 073 entries), and M-type stars (121 522 entries). This paper introduces the survey design, the observational and instrumental limitations, data reduction and analysis, and some caveats. A description of the FITS structure of spectral files and parameter catalogs is also provided

Data release of the LAMOST pilot survey

This paper describes the data release of the LAMOST pilot survey, which includes data reduction, calibration, spectral analysis, data products and data access. The accuracy of the released data and the information about the FITS headers of spectra are also introduced. The released data set includes 319 000 spectra and a catalog of these objects

CEPC Technical Design Report -- Accelerator

International audienceThe Circular Electron Positron Collider (CEPC) is a large scientific project initiated and hosted by China, fostered through extensive collaboration with international partners. The complex comprises four accelerators: a 30 GeV Linac, a 1.1 GeV Damping Ring, a Booster capable of achieving energies up to 180 GeV, and a Collider operating at varying energy modes (Z, W, H, and ttbar). The Linac and Damping Ring are situated on the surface, while the Booster and Collider are housed in a 100 km circumference underground tunnel, strategically accommodating future expansion with provisions for a Super Proton Proton Collider (SPPC). The CEPC primarily serves as a Higgs factory. In its baseline design with synchrotron radiation (SR) power of 30 MW per beam, it can achieve a luminosity of 5e34 /cm^2/s^1, resulting in an integrated luminosity of 13 /ab for two interaction points over a decade, producing 2.6 million Higgs bosons. Increasing the SR power to 50 MW per beam expands the CEPC's capability to generate 4.3 million Higgs bosons, facilitating precise measurements of Higgs coupling at sub-percent levels, exceeding the precision expected from the HL-LHC by an order of magnitude. This Technical Design Report (TDR) follows the Preliminary Conceptual Design Report (Pre-CDR, 2015) and the Conceptual Design Report (CDR, 2018), comprehensively detailing the machine's layout and performance, physical design and analysis, technical systems design, R&D and prototyping efforts, and associated civil engineering aspects. Additionally, it includes a cost estimate and a preliminary construction timeline, establishing a framework for forthcoming engineering design phase and site selection procedures. Construction is anticipated to begin around 2027-2028, pending government approval, with an estimated duration of 8 years. The commencement of experiments could potentially initiate in the mid-2030s

CEPC Technical Design Report -- Accelerator

International audienceThe Circular Electron Positron Collider (CEPC) is a large scientific project initiated and hosted by China, fostered through extensive collaboration with international partners. The complex comprises four accelerators: a 30 GeV Linac, a 1.1 GeV Damping Ring, a Booster capable of achieving energies up to 180 GeV, and a Collider operating at varying energy modes (Z, W, H, and ttbar). The Linac and Damping Ring are situated on the surface, while the Booster and Collider are housed in a 100 km circumference underground tunnel, strategically accommodating future expansion with provisions for a Super Proton Proton Collider (SPPC). The CEPC primarily serves as a Higgs factory. In its baseline design with synchrotron radiation (SR) power of 30 MW per beam, it can achieve a luminosity of 5e34 /cm^2/s^1, resulting in an integrated luminosity of 13 /ab for two interaction points over a decade, producing 2.6 million Higgs bosons. Increasing the SR power to 50 MW per beam expands the CEPC's capability to generate 4.3 million Higgs bosons, facilitating precise measurements of Higgs coupling at sub-percent levels, exceeding the precision expected from the HL-LHC by an order of magnitude. This Technical Design Report (TDR) follows the Preliminary Conceptual Design Report (Pre-CDR, 2015) and the Conceptual Design Report (CDR, 2018), comprehensively detailing the machine's layout and performance, physical design and analysis, technical systems design, R&D and prototyping efforts, and associated civil engineering aspects. Additionally, it includes a cost estimate and a preliminary construction timeline, establishing a framework for forthcoming engineering design phase and site selection procedures. Construction is anticipated to begin around 2027-2028, pending government approval, with an estimated duration of 8 years. The commencement of experiments could potentially initiate in the mid-2030s