Mesoporous hollow silica spheres as micro-water-tanks in proton exchange membranes

In order to decrease the swelling of Nafion^® and reduce the dependency of proton conductivity on high relative humidity (RH), mesoporous hollow silica spheres were synthesized and dispersed in Nafion matrix as micro-water-tanks in the proton exchange membranes (PEM). The morphologies of MHSi and Nafion/MHSi composite membranes are characterized by SEM and TEM. The effects of MHSi on water uptake, swelling, dehydration rate and proton conductivity of the composite membranes were investigated. The results show that, with a suitable portion of MHSi in the membrane, composite PEMs with enhanced water uptake, reduced swelling and improved proton conductivity are obtained.     

三氟化硼引发四氢呋喃聚合的研究——Ⅱ. 水的影响

<正> 分子量在3000以下的四氢呋喃聚合产物-聚丁二醇(PTMG)是重要的工业原料。前报中我们已证明用BF_3-环氧氯丙烷(ECH)引发四氢呋喃(THF)聚合时引发效率较高,在这一基础上有希望通过在聚合体系中加水以达到控制产物分子量的目的。 文献上对水在BF_3-ECH引发THF聚合反应中作用的研究不多,Kyzaeb等人     

Ferroelectric Polarization Modulated Facet-selective Charge Separation in Bi4NbO8Cl Single Crystal for Boosting Visible-light Driven Bifunctional Water Splitting

Developing bifunctional water-splitting photocatalysts is meaningful, but challenged by the harsh requirements of specific-facet single crystals with spatially separated reactive sites and anisotropic charge transfer paths contributed by well-built charge driving force. Herein, tunable ferroelectric polarization is introduced in Bi₄NbO₈Cl single crystal nanosheets to strengthen the orthogonal charge transfer channels. By manipulating the in-plane polarization from octahedral off-centering of Nb⁵⁺ and out-of-plane polarization from lone pair electron effect of anisotropic Bi³⁺, both the fast charge recombination in bulk catalyst and the process of charge trapping into surface states can be effectively modulated. Collaborating with modest polarization electric field and facet junction induced built-in electric field, cooperative charge tractive force is constructed, which reinforces the spatial separation and migration of photogenerated electrons and holes to {110} reductive site facet and {001} oxidation site facet, respectively. While excessive polarization charges impair the facet-selective charge separation characteristics and conversely promote charge recombination on the surface. As a result, polarity-optimized Bi₄NbO₈Cl shows an excellent H₂ and O₂ evolution rate of 54.21 and 36.08 μmol ⋅ h⁻¹ in the presence of sacrificial reagents under visible light irradiation. This work unveils the function of ferroelectric polarization in tuning the intrinsic facet-selective charge transfer process of photocatalysts.     

离聚体的化学物理功能研究——稀土系离聚体的吸水性能研究

稀土系离聚体由于其独特的结构特征,具有较一般离聚体大得多的吸水性能。本文系统地研究了离聚体中不同稀土金属离子、不同可离子化基团含量、不同中和度、不同反离子以及温度和时间的变化对离聚体吸水性能的影响规律,为离聚体的性能表征及使用提供了必要的应用参数。     

水包水乳液的合成及其相组成的研究

系统地研究了聚丙烯酰胺(PAM)-聚乙二醇(PEG)、聚丙烯酸钠(PSA)-PEG水包水乳液的合成条件,从相图上得到上述乳液能够稳定存在的区域,用极谱并结合核磁共振、激光拉曼光谱和相差显徽镜分析该高分子体系,结果表明,PEG溶液为连续相,PAM和PSA溶液分别为各自体系的分散相,两相之间无作用。     

Boosting Reactive Oxygen Species Generation Using Inter-Facet Edge Rich WO3 Arrays for Photoelectrochemical Conversion

Water oxidation reaction leaves room to be improved in the development of various solar fuel productions, because of the kinetically sluggish 4-electron transfer process of oxygen evolution reaction. In this work, we realize reactive oxygen species (ROS), H₂O₂ and OH⋅, formations by water oxidation with total Faraday efficiencies of more than 90 % by using inter-facet edge (IFE) rich WO₃ arrays in an electrolyte containing CO₃²⁻. Our results demonstrate that the IFE favors the adsorption of CO₃²⁻ while reducing the adsorption energy of OH⋅, as well as suppresses surface hole accumulation by direct 1-electron and indirect 2-electron transfer pathways. Finally, we present selective oxidation of benzyl alcohol by in situ using the formed OH⋅, which delivers a benzaldehyde production rate of ≈768 μmol h⁻¹ with near 100 % selectivity. This work offers a promising approach to tune or control the oxidation reaction in an aqueous solar fuel system towards high efficiency and value-added product.     

Characterization of plants and seaweeds based corrosion inhibitors against microbially influenced corrosion in a cooling tower water environment

This study compares the inhibitory activities of methanolic extraction of various plants including Artemisia pallens (MEAP), mangrove leaves like Rhizophora mangle (MERM), Avicennia marina (MEAM) and seaweeds such as Pandia povanica (MEPP), Sargassum tenerrimum (MEST) on the corrosion of mild steel (MS) coupons that were incubated on Pseudomonas stutzeri (P. stutzeri) SKR4 strain isolated from the cooling tower water (CTW). The activities of inhibitors are found using GCMS analysis and interactions between microbes and inhibitors were examined in the test for antibacterial activity, minimal inhibition concentration, biofilm formation assay. These all show an excellent inhibitory effect against P. stutzeri. The weight loss, impedance spectroscopy, and Tafel polarization tests used to validate the corrosion investigations show that the inhibitors MEAP-75, MERM-71, MEAM-69, MEPP-66 and MEST-63 % are effective at inhibiting corrosion at 25 ppm. According to Potentiodynamic polarization plots, these five inhibitors act as mixed-type inhibitors. The surface investigation of MS metals by FTIR, SEM, XRD to examine the biofilm surface and it revealed deep pitting corrosion in the bacterial system. In the conclusion, eco-friendly green inhibitors have controlled the biocorrosion in cooling tower water and are recommended for usage in industries as an alternative to environmentally hazardous inhibitors.     

Moisture sorption isotherms of whole and fractionated date-pits: Measurement and theoretical modelling

Moisture sorption properties of whole date-pits (WDP) and three fractionated date-pits; defatted date-pits (DDP), residue (REP) and supernatant (SUP) fractions were studied. Sorption isotherms were measured using Differential Thermal and Humidity chamber at different temperatures (10, 30, 50, 70 and 90 °C) and relative humidity ranged from 0.05 to 0.9. Crossovers of isotherm curves were observed for all fractions between different temperatures. At 30 °C, BET-monolayers of WDP, DDP, REP and SUP were 4.9, 4.2, 3.8 and 3.2 g/100 g ds, respectively. The complete isotherms (i.e. 0.05–0.90 water activity) were modelled by GAB with high coefficient of determination (i.e. 0.944 to 0.999). In the cases of WDP and DDP, the isosteric heat plots showed increasing trends with the decreased moisture and peaks at moisture 0.025 and 0.040 g/100 g ds. Unlike all fractions, DDP isokinetic temperatures T_is (i.e. 97.4 °C) was lower than isobound temperatures T_ib (i.e. 145.0 °C) indicating complete removal of bound water occurred at higher temperature as compared to the temperature when all reactions reached at the same. The moisture sorption isotherm characteristics could be used in determining the end point of drying and storage stability as well as packaging design of the date-pits and their fractions.     

Dimension Engineering in Noble-Metal-Based Electrocatalysts for Water Splitting

Dimension engineering plays a critical role in determining the electrocatalytic performance of catalysts towards water electrolysis since it is highly sensitive to the surface and interface properties. Bearing these considerations into mind, intensive efforts have been devoted to the rational dimension design and engineering, and many advanced nanocatalysts with multidimensions have been successfully fabricated. Aiming to provide more guidance for the fabrication of highly efficient noble-metal-based electrocatalysts, this review has focused on the recent progress in dimension engineering of noble-metal-based electrocatalysts towards water splitting, including the advanced engineering strategies, the application of noble-metal-based electrocatalysts with distinctive geometric structure from 0D to 1D, 2D, 3D, and multidimensions. In addition, the perspective insights and challenges of the dimension engineering in the noble-metal-based electrocatalysts is also systematically discussed.     

High-Performance Alkaline Seawater Electrolysis with Anomalous Chloride Promoted Oxygen Evolution Reaction

A highly selective and durable oxygen evolution reaction (OER) electrocatalyst is the bottleneck for direct seawater splitting because of side reactions primarily caused by chloride ions (Cl⁻). Most studies about OER catalysts in seawater focus on the repulsion of the Cl⁻ to reduce its negative effects. Herein, we demonstrate that the absorption of Cl⁻ on the specific site of a popular OER electrocatalyst, nickel-iron layered double hydroxide (NiFe LDH), does not have a significant negative impact; rather, it is beneficial for its activity and stability enhancement in natural seawater. A set of in situ characterization techniques reveals that the adsorption of Cl⁻ on the desired Fe site suppresses Fe leaching, and creates more OER-active Ni sites, improving the catalyst's long-term stability and activity simultaneously. Therefore, we achieve direct alkaline seawater electrolysis for the very first time on a commercial-scale alkaline electrolyser (AE, 120 cm² electrode area) using the NiFe LDH anode. The new alkaline seawater electrolyser exhibits a reduction in electricity consumption by 20.7 % compared to the alkaline purified water-based AE using commercial Ni catalyst, achieving excellent durability for 100 h at 200 mA cm⁻².