[PCu(H2O)Mo11O39]5－/PAMAM多层复合膜的制备及电化学性质研究

通过电化学扫描法在玻碳电极和导电玻璃基底上组装制备过渡金属铜取代多金属氧酸盐[PCu(H₂O)Mo₁₁O₃₉]^5－和4代聚酰胺-胺(G4-PAMAM)交替沉积的复合膜. X射线光电子能谱(XPS), 原子力显微镜(AFM), 循环伏安法(CV)结果表明复合膜成功制备且有好的均匀性. 多层膜中的[PCu(H₂O)Mo₁₁O₃₉]^5－与其在溶液中的氧化还原行为相比, 电子转移控制速率不同, 该多层膜修饰电极稳定性好, 对 的还原及抗坏血酸的氧化具有较好的电催化性能.     

A Photoactivated Cu–CeO2 Catalyst with Cu‐[O]‐Ce Active Species Designed through MOF Crystal Engineering

Fully utilizing solar energy for catalysis requires the integration of conversion mechanisms and therefore delicate design of catalyst structures and active species. Herein, a MOF crystal engineering method was developed to controllably synthesize a copper–ceria catalyst with well‐dispersed photoactive Cu‐[O]‐Ce species. Using the preferential oxidation of CO as a model reaction, the catalyst showed remarkably efficient and stable photoactivated catalysis, which found practical application in feed gas treatment for fuel cell gas supply. The coexistence of photochemistry and thermochemistry effects contributes to the high efficiency. Our results demonstrate a catalyst design approach with atomic or molecular precision and a combinatorial photoactivation strategy for solar energy conversion.     

Comparison of Multiple Bioactive Constituents in the Corolla and Other Parts of Abelmoschus manihot

Abelmoschus manihot (L.) Medic (AM), called Huangshukui in Chinese, is a widely used medicinal plant. Each part of AM has medicinal value, including Abelmoschi Radix (AR), Abelmoschi Herba (AH), Abelmoschi Folium (AF), Abelmoschi Corolla (AC), and Abelmoschi Semen (AS). However, only AC is documented in the Chinese Pharmacopoeia. In order to investigate whether there is any difference between AC and the other parts of AM, an analytical method based on ultra-fast performance liquid chromatography coupled with triple quadrupole-linear ion trap mass spectrometry (UFLC-QTRAP-MS/MS) was established for the simultaneous determination of 35 constituents in different parts of AM. Moreover, principal components analysis (PCA) and partial least squares discriminant analysis (PLS-DA) were applied to classify and evaluate the different parts of AM based on the content of the 35 constituents. The total contents of the 35 constituents in AC were significantly higher than in the other parts of AM and the results revealed significant differences between AC and the other parts of AM. Eight constituents were remarkably related to the sample classifications. This research does not just provide the basic information for revealing the distribution patterns in different parts of AM from the same origin, but also complements some of the scientific data for the comprehensive quality evaluation of AC.     

非对称布置液滴在波纹状基底上的聚并过程

基于润滑理论建立在波纹基底上两个含表面活性剂液滴聚并的演化模型，模拟液滴位于波纹基底波峰和波谷处的聚并过程，分析液滴初始间距和基底高度对聚并的影响，并与对称布置液滴进行比较.结果表明：液滴高度随时间呈现五个阶段变化；活性剂浓度在短时间内完成三个阶段变化；初始间距的增大将延长液滴及活性剂聚并时间；增大基底高度将缩短液滴及活性剂聚并时间；非对称液滴相较于对称液滴聚并时间短，聚并速度快.     

Structural Features of ZnO@e-HNbWO6 Nanocomposite and Its Photocatalytic Performance

Russian Journal of Physical Chemistry A - ZnO@e-HNbWO6 nanocomposite was prepared by exfoliation-restacking method from HNbWO6 nanosheets and ZnO nanoparticle sol. The as-prepared materials were...     

Effect of PEG molecular weight on the crystal structure and electrochemical performance of LiV3O8

This paper describes systematic studies on the effect of polyethylene glycol (PEG) molecular weight on the crystal structure and particularly the electrochemical performance of LiV₃O₈. Scanning electron microscopy results indicate that after the decomposition of PEG, the structure of resultant products exhibits differences in morphology (shape, particle size, and specific surface area). The electrochemical results show that LiV₃O₈ cathode material treated by PEG (mean molecular weight of 10,000) has greater initial discharge capacity and better cyclic stability than other materials treated with PEG of different molecular weight. Its initial discharge capacity is 282.1 mAh g⁻¹ and maintains 222.2 mAh/g after 50 cycles in 0.5 C rates (150 mA g⁻¹).     

考虑供应链渠道冲突的零售商自有品牌产品定价方法

自有品牌产品定价是电子商务环境下零售商实施渠道管理的关键因素,其合理与否直接影响到零售商利润和供应链稳定.鉴于此,针对存在供应链渠道冲突的零售商自有品牌定价问题,从协调的角度,利用对偶理论与优化模型,构建了基于最小协调成本的零售商自有品牌产品定价决策方法,并利用其探讨协调的经济意义,求解零售商自有品牌产品最优定价.结果表明,所构建的模型能够有效描述和解决零售商自有品牌产品定价问题,并在一定程度上消除供应链渠道冲突,保证供应商和零售商长期有效合作和供应链可持续发展.     

Field-portable ratiometric fluorescence imaging of dual-color label-free carbon dots for uranyl ions detection with cellphone-based optical platform

Under the public spotlight, uranyl (UO₂²⁺) ions has attracted considerable attention for the extreme radioactive and chemical toxicity to ourselves and our environment. Herein, we present a simple and effective ratiometric fluorescence imaging method for the visualizing and quantitative detection UO₂²⁺ ions by cellphone-based optical platform. The sensing solution was prepared by mixing label-free red carbon dots (r-CDs) and blue carbon dots (b-CDs) together with a fixed photoluminescence intensity ratio of 4:1. When UO₂²⁺ ions were added, the fluorescence of r-CDs can be selectively quenched, while the fluorescence of b-CDs remains stable without spectral changes. With the gradually increase the amounts of UO₂²⁺ ions, the different response of dual-color CDs resulted in a signification color evolution from deep red to dark purple under the ultraviolet (UV) light illumination. Then, a cellphone-based optical platform was constructed for directly imaging the color change of the samples, and the built-in Colorpicker APP quickly output the red, green and blue (RGB) channel values of these images within one second. Interesting, there was a linear relationship between the ratio of red and blue (R/B) channel values and UO₂²⁺ ions concentration from 0 μmol/L to 30.0 μmol/L (R² = 0.92804) with the detection limit of ~8.15 μmol/L (signal-to-noise ratio of 3). In addition, the optical platform has also been applied to the quantification of UO₂²⁺ ions in tap water and river water sample. With the advantage of low-cost, portable, easy to operation, we anticipate that this method would greatly improve the accessibility of UO₂²⁺ ions detection even in resource-limited areas.     

Improved Dehydrogenation Properties of LiBH4 Using Catalytic Nickel‐ and Cobalt‐based Mesoporous Oxide Nanorods

Lithium borohydride (LiBH₄) with a theoretical hydrogen storage capacity of 18.5 wt % has attracted intense interest as a high‐density hydrogen storage material. However, high dehydrogenation temperatures and limited kinetics restrict its practical applications. In this study, mesoporous nickel‐ and cobalt‐based oxide nanorods (NiCo₂O₄, Co₃O₄ and NiO) were synthesized in a controlled manner by using a hydrothermal method and then mixed with LiBH₄ by ball milling. It is found that the dehydrogenation properties of LiBH₄ are remarkably enhanced by doping the as‐synthesized metal oxide nanorods. When the mass ratio of LiBH₄ and oxides is 1:1, the NiCo₂O₄ nanorods display the best catalytic performance owing to the mesoporous rod‐like structure and synergistic effect of nickel and cobalt active species. The initial hydrogen desorption temperature of the LiBH₄‐NiCo₂O₄ composite decreases to 80 °C, which is 220 °C lower than that of pure LiBH₄, and 16.1 wt % H₂ is released at 500 °C for the LiBH₄‐NiCo₂O₄ composite. Meanwhile, the composite also exhibits superior dehydrogenation kinetics, which liberates 5.7 wt % H₂ within 60 s and a total of 12 wt % H₂ after 5 h at 400 °C. In comparison, pure LiBH₄ releases only 5.3 wt % H₂ under the same conditions.     

Hydrogen Doping into MoO3 Supports toward Modulated Metal–Support Interactions and Efficient Furfural Hydrogenation on Iridium Nanocatalysts

As promising supports, reducible metal oxides afford strong metal–support interactions to achieve efficient catalysis, which relies on their band states and surface stoichiometry. In this study, in situ and controlled hydrogen doping (H doping) by means of H₂ spillover was employed to engineer the metal–support interactions in hydrogenated MoO_x‐supported Ir (Ir/H?MoO_x) catalysts and thus promote furfural hydrogenation to furfuryl alcohol. By easily varying the reduction temperature, the resulting H doping in a controlled manner tailors low‐valence Mo species (Mo⁵⁺ and Mo⁴⁺) on H?MoO_x supports, thereby promoting charge redistribution on Ir and H?MoO_x interfaces. This further leads to clear differences in H₂ chemisorption on Ir, which illustrates its potential for catalytic hydrogenation. As expected, the optimal Ir/H?MoO_x with controlled H doping afforded high activity (turnover frequency: 4.62 min^?1) and selectivity (>99 %) in furfural hydrogenation under mild conditions (T=30 °C, P =2 MPa), which means it performs among the best of current catalysts.