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In this work, we introduced halogen-substituted chiral molecules as A-site cations to synthesize a series of novel organic-inorganic hybrid two-dimensional (2D) chiral perovskite materials (R-X-p-mBZA)2PbBr4 (X= H, F, Cl, Br;...

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A composite catalyst was obtained by covalently linking G4-NH 2 dendrimers and 1,10-phenanthroline-5-carboxylic acid on the surface of carbon powder, and the composite was named as PMPhen/C. In order to improve the catalytic performance of the composite, copper ions (II) were introduced to PMPhen/C by complex to form the PMPhen-Cu/C catalyst. Scanning electron microscope (SEM) and X-ray photoelectron spectroscopy (XPS) were applied to investigate the surface microstructure and elemental compositions of the catalysts. The results from electrochemical analysis show that PMPhen/C reduced oxygen to hydrogen peroxide (H 2 O 2 ) through a two-electron transfer process. PMPhen-Cu/C could reduce oxygen to water through a four-electron pathway. Except the slightly lower initial reduction potential, PMPhen-Cu/C has a comparable oxygen reduction ability (ORR) to that of the commercially available Pt/C catalyst, which makes it a potential candidate as the cathodic catalyst in some fuel cells running in neutral medium, such as a microbial fuel cell. Catalysts 2018, 8, 245 2 of 21in the current study of ORR catalysts [7]. Nitrogen and transition metals introduced in a certain way are considered to be key factors for the function of the ORR catalysts, which usually exist in the form of M-N x (M = Fe, Co, Ni, Mn, Cu, etc.) [13]. Meanwhile, the carbon materials were also frequently used as the supporting materials for the catalysts due to their high conductivity, porous microstructure and high specific surface area. The porous structure of carbon materials can not only increase the contact area between catalyst and oxygen, but also construct more channels for the diffusion of O 2 , H 2 O, H 2 O 2 and other additional intermediates and can be beneficial to improve the ORR activities of the catalysts [14]. Apart from providing supporting carbon material, another effective approach for improving the ORR activities of the catalysts was the pyrolysis of the M-N x -containing materials under inert atmosphere, which is beneficial to the fixation and optimization of the structure of the M-N x unit and then improving the stabilities of the catalysts [1,15]. The pyrolysis process is helpful for the doping of hetero atoms and transitional metal atoms on the surface of carbon materials, but the disadvantage is that the reaction of the doping process is unordered, which brings trouble to the quantitative analysis of the relationship between the ORR activities and the catalyst precursors. At present, the nitrogen-containing precursors include polypyrrole, porphyrins, polyphthalocyanines, polyaniline (PANI), phenanthroline (Phen), etc. [16][17][18][19].Many reports adopt some of the nitrogen-containing heterocyclic ligands as the nitrogen source for the preparation of M-N x -containing catalyst, and the M-N x unit has been considered as the active site of the catalysts, which were in the form of the non-pyrolysis state [20][21][22]. During the pyrolysis process, the complexing metal ions contributed to the improved ORR activity by promoting the...

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Accurate high spatial resolution snow depth mapping in arid and semi-arid regions is of great importance for snow disaster assessment and hydrological modeling. However, due to the complex topography and low spatial-resolution microwave remote-sensing data, the existing snow depth datasets have large errors and uncertainty, and actual spatiotemporal heterogeneity of snow depth cannot be effectively detected. This paper proposed a deep learning approach based on downscaling snow depth retrieval by fusion of satellite remote-sensing data with multiple spatial scales and diverse characteristics. The (Fengyun-3 Microwave Radiation Imager) FY-3 MWRI data were downscaled to 500 m resolution to match Moderate-resolution Imaging Spectroradiometer (MODIS) snow cover, meteorological and geographic data. A deep neural network was constructed to capture detailed spectral and radiation signals and trained to retrieve the higher spatial resolution snow depth from the aforementioned input data and ground observation. Verified by in situ measurements, downscaled snow depth has the lowest root mean square error (RMSE) and mean absolute error (MAE) (8.16 cm, 4.73 cm respectively) among Environmental and Ecological Science Data Center for West China Snow Depth (WESTDC_SD, 9.38 cm and 5.36 cm), the Microwave Radiation Imager (MWRI) Ascend Snow Depth (MWRI_A_SD, 9.45 cm and 5.49 cm) and MWRI Descend Snow Depth (MWRI_D_SD, 10.55 cm and 6.13 cm) in the study area. Meanwhile, downscaled snow depth could provide more detailed information in spatial distribution, which has been used to analyze the decrease of retrieval accuracy by various topography factors.

Abstract:In this work, a nitrogen-containing bidentate ligand named 5,5 -(9-octyl-9H-carbazole-2,7-diyl)bis(1,10-phenanthroline) (OCBP) was synthesized as a nitrogen precursor for making an oxygen reduction catalyst. The 1,10-phenanthroline unit provides a coordination site for copper ions, and the resulting Cu-N x unit may be responsible for the catalytic activities of the catalyst. Carbon black was selected as a support to improve the electroconductibility of the resulting catalyst. The metallo-supramolecule (Cu-SOCBP) was dispersed on the surface of Vulcan XC-72 carbon and was used as a catalyst (designated as Cu-SOCBP/C) for the oxygen reduction reaction (ORR). The microscope structure and surface components of the catalyst were acquired via scanning electron microscopy and X-ray photoelectron spectroscopy, as well as X-ray powder diffraction. The electrochemical property and ORR mechanism of Cu-SOCBP/C were analyzed using a variety of electroanalytical methods including cyclic voltammetry, electrochemical impedance spectroscopy, and linear sweep voltammetry. These results show that Cu-SOCBP/C was successfully synthesized and that ORR was achieved mainly via a four-electron transfer process to water. Thus, Cu-SOCBP/C was an effective catalyst and might have potential application as a cathodic catalyst in microbial fuel cells, which operate in an aqueous medium.