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91.
Well‐Defined Palladium Nanoparticles Supported on Siliceous Mesocellular Foam as Heterogeneous Catalysts for the Oxidation of Water 下载免费PDF全文
Dr. Oscar Verho Dr. Torbjörn Åkermark Dr. Eric V. Johnston Karl P. J. Gustafson Dr. Cheuk‐W. Tai Henrik Svengren Dr. Markus D. Kärkäs Prof. Jan‐E. Bäckvall Prof. Björn Åkermark 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(15):5909-5915
Herein, we describe the use of Pd nanoparticles immobilized on an amino‐functionalized siliceous mesocellular foam for the catalytic oxidation of H2O. The Pd nanocatalyst proved to be capable of mediating the four‐electron oxidation of H2O to O2, both chemically and photochemically. The Pd nanocatalyst is easy to prepare and shows high chemical stability, low leaching, and recyclability. Together with its promising catalytic activity, these features make the Pd nanocatalyst of potential interest for future sustainable solar‐fuel production. 相似文献
92.
木屑是一种在各种案件现场中出现几率较高的微量物证,但由于其化学组成复杂、难溶,高分子组分之间的差异不显著,所以一直未建立有效的鉴定方法.采用裂解-气相/质谱技术(PY-GC/MS)对不同树种木屑难溶物进行分析,结果发现:不同树种木屑难溶物的总离子流图特征相似,即每种木屑难溶物的总离子流图中都有一组特征峰.但个别组分有差异. 相似文献
93.
Jialei Du Prof. Zuofeng Chen Dr. Shengrong Ye Prof. Benjamin J. Wiley Prof. Thomas J. Meyer 《Angewandte Chemie (International ed. in English)》2015,54(7):2073-2078
Copper metal is in theory a viable oxidative electrocatalyst based on surface oxidation to CuIII and/or CuIV, but its use in water oxidation has been impeded by anodic corrosion. The in situ formation of an efficient interfacial oxygen‐evolving Cu catalyst from CuII in concentrated carbonate solutions is presented. The catalyst necessitates use of dissolved CuII and accesses the higher oxidation states prior to decompostion to form an active surface film, which is limited by solution conditions. This observation and restriction led to the exploration of ways to use surface‐protected Cu metal as a robust electrocatalyst for water oxidation. Formation of a compact film of CuO on Cu surface prevents anodic corrosion and results in sustained catalytic water oxidation. The Cu/CuO surface stabilization was also applied to Cu nanowire films, which are transparent and flexible electrocatalysts for water oxidation and are an attractive alternative to ITO‐supported catalysts for photoelectrochemical applications. 相似文献
94.
Nanometer‐Scale Water‐ and Proton‐Diffusion Heterogeneities across Water Channels in Polymer Electrolyte Membranes 下载免费PDF全文
Dr. Jinsuk Song Prof. Dr. Oc Hee Han Prof. Dr. Songi Han 《Angewandte Chemie (International ed. in English)》2015,54(12):3615-3620
Nafion, the most widely used polymer for electrolyte membranes (PEMs) in fuel cells, consists of a fluorocarbon backbone and acidic groups that, upon hydration, swell to form percolated channels through which water and ions diffuse. Although the effects of the channel structures and the acidic groups on water/ion transport have been studied before, the surface chemistry or the spatially heterogeneous diffusivity across water channels has never been shown to directly influence water/ion transport. By the use of molecular spin probes that are selectively partitioned into heterogeneous regions of the PEM and Overhauser dynamic nuclear polarization relaxometry, this study reveals that both water and proton diffusivity are significantly faster near the fluorocarbon and the acidic groups lining the water channels than within the water channels. The concept that surface chemistry at the (sub)nanometer scale dictates water and proton diffusivity invokes a new design principle for PEMs. 相似文献
95.
Dr. Guang‐Ping Hao Giovanni Mondin Dr. Zhikun Zheng Tim Biemelt Stefan Klosz René Schubel Prof. Alexander Eychmüller Prof. Stefan Kaskel 《Angewandte Chemie (International ed. in English)》2015,54(6):1941-1945
There is significant interest in high‐performance materials that can directly and efficiently capture water vapor, particularly from air. Herein, we report a class of novel porous carbon cuboids with unusual ultra‐hydrophilic properties, over which the synergistic effects between surface heterogeneity and micropore architecture is maximized, leading to the best atmospheric water‐capture performance among porous carbons to date, with a water capacity of up to 9.82 mmol g?1 at P/P0=0.2 and 25 °C (20 % relative humidity or 6000 ppm). Benefiting from properties, such as defined morphology, narrow pore size distribution, and high heterogeneity, this series of functional carbons may serve as model materials for fundamental research on carbon chemistry and the advance of new types of materials for water‐vapor capture as well as other applications requiring combined highly hydrophilic surface chemistry, developed hierarchical porosity, and excellent stability. 相似文献
96.
Comparison of copolymer emulsions of fluorine and siloxane‐containing acrylates with core–shell structure for water‐repellent cotton fabrics coatings 下载免费PDF全文
J. Lin C. Zheng M. N. Zhu Y. Z. Chen P. P. Lu Q. Liu X. F. Cai J. W. Zhuang X. M. Cai L. P. Liao G. Y. Yuan C. L. Xu 《先进技术聚合物》2015,26(1):68-76
This paper described the synthesis of copolymer emulsions of fluorine and siloxane‐containing acrylates for water‐repellent cotton fabrics coatings. Chemical composition, morphology structure, and properties of the latex copolymers were investigated by Fourier transform infrared (FTIR), dynamic light scattering (DLS), gel permeation chromatography (GPC), and transmission electron microscopy (TEM), thermogravimetric analysis (TGA), and scanning electron microscopy (SEM). Effects of water‐repellent functional monomers (Rf) on surface morphology, water contact angle, and water‐repellent properties of the coated fabric surface were also studied. The results indicated that Rf greatly influenced molecular mass distribution of the latex copolymers, the molecular aggregation states and orientation of Rf on the coated fabric surface, and water‐repellency of coated cotton fabrics. Copyright © 2014 John Wiley & Sons, Ltd. 相似文献
97.
Interface Engineering of a CoOx/Ta3N5 Photocatalyst for Unprecedented Water Oxidation Performance under Visible‐Light‐Irradiation 下载免费PDF全文
Shanshan Chen Dr. Shuai Shen Guiji Liu Yu Qi Prof. Fuxiang Zhang Prof. Can Li 《Angewandte Chemie (International ed. in English)》2015,54(10):3047-3051
Cocatalysts have been extensively used to promote water oxidation efficiency in solar‐to‐chemical energy conversion, but the influence of interface compatibility between semiconductor and cocatalyst has been rarely addressed. Here we demonstrate a feasible strategy of interface wettability modification to enhance water oxidation efficiency of the state‐of‐the‐art CoOx/Ta3N5 system. When the hydrophobic feature of a Ta3N5 semiconductor was modulated to a hydrophilic one by in situ or ex situ surface coating with a magnesia nanolayer (2–5 nm), the interfacial contact between the hydrophilic CoOx cocatalyst and the modified hydrophilic Ta3N5 semiconductor was greatly improved. Consequently, the visible‐light‐driven photocatalytic oxygen evolution rate of the resulting CoOx/MgO(in)–Ta3N5 photocatalyst is ca. 23 times that of the pristine Ta3N5 sample, with a new record (11.3 %) of apparent quantum efficiency (AQE) under 500–600 nm illumination. 相似文献
98.
Photoelectrochemical Hydrogen Production in Alkaline Solutions Using Cu2O Coated with Earth‐Abundant Hydrogen Evolution Catalysts 下载免费PDF全文
Carlos G. Morales‐Guio Laurent Liardet Dr. Matthew T. Mayer Dr. S. David Tilley Prof. Dr. Michael Grätzel Prof. Dr. Xile Hu 《Angewandte Chemie (International ed. in English)》2015,54(2):664-667
The splitting of water into hydrogen and oxygen molecules using sunlight is an attractive method for solar energy storage. Until now, photoelectrochemical hydrogen evolution is mostly studied in acidic solutions, in which the hydrogen evolution is more facile than in alkaline solutions. Herein, we report photoelectrochemical hydrogen production in alkaline solutions, which are more favorable than acidic solutions for the complementary oxygen evolution half‐reaction. We show for the first time that amorphous molybdenum sulfide is a highly active hydrogen evolution catalyst in basic medium. The amorphous molybdenum sulfide catalyst and a Ni–Mo catalyst are then deposited on surface‐protected cuprous oxide photocathodes to catalyze sunlight‐driven hydrogen production in 1 M KOH. The photocathodes give photocurrents of ?6.3 mA cm?2 at the reversible hydrogen evolution potential, the highest yet reported for a metal oxide photocathode using an earth‐abundant hydrogen evolution reaction catalyst. 相似文献
99.
采用液相色谱串联质谱法(LC/MS/MS)测定含藻水氯消毒产生7种亚硝胺类(NAms)消毒副产物(NDMA,NMEA,NDEA,NDPA,NDBA,NPyr,NPip).方法检出限分别为5.0,14,8.6,3.6,2.9,6.3和4.9 ng/L,相关系数r>0.999.除NDBA回收率(60%)较低外,其余6种亚硝胺回收率均在80%~120%之间,相对标准偏差为1.4%~12.6%.分别以藻原液和消毒后藻液配制基质标准曲线,采用其与纯水标准曲线斜率之比评估基质效应.藻原液的基质效应为0.79 ~0.94,藻液消毒后NDMA基质效应为0.36,其他亚硝胺为0.63~0.96.应用此方法检测了自来水、富营养江河水、景观水及藻类悬浮液氯消毒后的亚硝胺含量. 相似文献
100.
研究了H2O对Ni/MgAlO催化剂上丙酮加氢为异丙醇的催化反应的影响。结果发现,在丙酮中添加少量H2O可提高丙酮转化率,但超过5%的H2O量则会显著降低催化剂活性。吸附量热结果表明,催化剂表面吸附少量H2O会明显降低异丙醇的吸附热,但对丙酮吸附热的影响较小,这也许是反应体系中少量的H2O能促进丙酮加氢活性的原因之一。当催化剂表面吸附较多H2O后,丙酮、异丙醇和H2的吸附热都降低了,因此反而抑制了丙酮的加氢反应。此外,红外光谱结果表明,预吸附水抑制了催化剂表面异丙醇脱氢生成丙酮,并抑制吸附的丙酮在表面生成烯醇盐或异丙叉丙酮等物种,这也许是少量水能促进丙酮加氢生成异丙醇的另一个重要原因。 相似文献