Electrocatalytic oxidation of formaldehyde and methanol on Ni(OH)2/Ni electrode

A nickel hydroxide-modified nickel electrode (Ni(OH)₂/Ni) was successfully prepared by the cyclic voltammetry (CV) method and the electrocatalytic properties of the electrode for formaldehyde and methanol oxidation have been investigated respectively. The Ni(OH)₂/Ni electrode exhibits high electrocatalytic activity in the reaction. A new method has been developed for formaldehyde determination at the nickel hydroxide-modified nickel electrode and the experimental parameters were optimized. The oxidation peak current is linearly proportional to the concentration of formaldehyde in the range of 7.0 × 10^?5 to 1.6 × 10^?2 M with a detection limit of 2.0 × 10^?5 M. Recoveries of artificial samples are between 93.3 and 103.5%. The effect of scan rate and methanol concentration on the electrochemical behavior of methanol were investigated respectively.     

火焰原子吸收法快速分析硫酸中铅镉铜锌

文中直接取硫酸样品3ml于装有约10ml水的25ml比色管中,加入碘化钾溶液2ml,用水稀至刻度。加入甲基异丁酮5ml,萃取lmin,分层后,在有机相中测定铅、镉、铜含量;在水相中测定锌含量。方法的加标回收率为98.9％～103％,精密度1.8％～4.3％,标准曲线法和标准加入法结果相近,倍比试验结果亦相吻合,方法快速简便、准确,适合于工业中的快速分析。     

Preparation and evaluation of uniform-sized molecularly imprinted polymer beads used for the separation of sulfamethazine

Uniform-sized molecularly imprinted polymer (MIP) beads were prepared using a one-step swelling and polymerization method. The obtained sulfamethazine (SMZ)-imprinted polymer showed high affinity and selectivity toward SMZ and other structurally related sulfonamides in acetonitrile or water-acetonitrile mobile phases, particularly in high aqueous systems. The column performance of the MIPs for SMZ and its analogues could be improved by elevating the column temperature and optimizing the flow rate. The hydrogen-bonding effect plays a significant role in the recognition process of SMZ-imprinted polymer systems in organic media, while the ion-exchange effect, as well as hydrophobic effect, dominates the retention mechanism in aqueous-rich media, in addition to shape recognition.     

二氧化碳氧化丙烷制丙烯催化反应的研究铬镁铝复合氧化物催化剂的制备、表面微量吸附量热及催化性能

以共沉淀法合成的铬镁铝类水滑石为前体,制备了一系列不同原子比的铬镁铝复合氧化物,研究了其对二氧化碳氧化丙烷制丙烯反应的催化性能.采用微量吸附量热技术,以CO2和NH3为探针分子定量地表征了样品表面酸碱中心的强度和数量,并与其催化性能进行了关联.结果表明,Cr:Mg:Al原子比为1:1:1的催化剂具有较大的比表面积(94.5m2/g),样品中Mg(Al1.5Cr05)O4物相的含量最多.样品表面存在数量较多强度较强的酸性中心和数量最少强度较弱的碱性中心,对NH3吸附,它的吸附热为145 kJ/mol,吸附覆盖度为3.55μmol/m2;对CO2吸附,它的吸附热为115kJ/mol,吸附覆盖度为0.063μmol/m2.该样品的催化活性最高,在温度为650℃,CO2/C3H8摩尔比为3.6,GHSV(C3H8)为3000 h-1时,C3H8的转化率为22.8%,C3H6的选择性为83.5%,收率为19.1%.     

Superhydrophobic surface based on micro/nano structured ZnO nanosheets for high-efficiency anticorrosion

Journal of Solid State Electrochemistry - There are two key factors in the fabrication of superhydrophobic surfaces. One is to have the appropriate micro/nano structure, and the other is to reduce...     

二维/二维S-型Bi3NbO7/g-C3N4异质结光催化剂驱动选择性CO2还原制CH4

人工光合作用可直接将二氧化碳转化为一系列碳氢化合物,实现大气中的碳循环,被视为一种既能解决能源短缺又能减少温室气体,进而改善人类生存环境的新型绿色技术.光催化二氧化碳还原体系需要合适的耦合氧化还原反应,以及对外界光源的有效利用以产生足够电子参与反应,因此构建高催化活性和高选择性的催化体系仍然面临着巨大挑战.此外,二维纳米结构(2D)由于具有比表面积大、离子的迁移路径短以及独特的平层电子转移轨道等特性,被证实有利于光催化还原CO₂过程.其中,Bi₃NbO₇特殊的片层结构和合适的能带位置,使其在光催化还原CO₂反应中表现出良好的催化性能.然而,Bi₃NbO₇的光生载流子易复合及反应中光腐蚀严重等缺陷导致其光利用率较低,限制了其实际应用.因此,构建S-型异质结是提高复合材料光催化活性的一种有前途的策略.S-型异质结不仅能有效地分离光生电子和空穴,而且这一电子转移过程赋予了复合物最大的氧化还原能力.同时,S-型光催化体系不仅拥有同样的强氧化和强还原能力,还可显著抑制副反应的发生及副产物的产生,有利于CO₂还原反应的高选择性进行.本文利用简易的溶剂热法制备了一系列S-型Bi₃NbO₇/g-C₃N₄(BNO/UCN)异质结光催化剂,与其纯组分催化剂相比,表现出优异的光催化还原CO₂活性,g-C₃N₄含量为80wt%的BNO/UCN-3光催化剂催化CO₂生成CH₄产率为37.59μmol·g^-1h^-1,是g-C₃N₄的15倍,CH₄选择性为90%;且循环反应10次后仍保持较高的活性及CH4选择性.光催化活性及选择性的显著增强是由于二维分布的纳米结构和S-型电荷转移路径.在可见光照射下,界面内建电场、带边缘弯曲和库仑相互作用协同促进了复合物相对无用的电子和空穴的复合.因此,剩余的电子和空穴具有较高的还原性和氧化性,使复合材料具有较高的氧化还原能力.自由基捕获实验、电子顺磁共振实验和原位X射线光电子能谱实验结果表明,光催化剂中的电子迁移遵循S-型异质结机理.综上,本文不仅为新型S-型异质结CO₂还原光催化剂的设计和制备提供了新方法,而且为未来解决能源短缺及实现碳中和目标提供一定的实验及理论依据.     

压力诱导相变原位构建BiVO4/Bi0.6Y0.4VO4型异质结增强光催化全解水性能

光催化完全分解水制氢是一个在粉末颗粒中实现多个串行物理化学步骤的复杂反应过程.这一过程在理论上具有体系简单、成本低、易操作等特点.然而,单步光激发系统中通常存在严重的光生载流子复合,这极大地制约了光催化的整体效率.利用能带结构不同的半导体合理构建异质结催化剂被认为是解决这一难题的重要途径之一.特别是近年来,S型异质结概念的提出为设计异质结结构以及分析不同半导体之间的载流子迁移问题提供了新的思路.本文以小粒径BiVO₄/Bi_0.6Y_0.4VO₄(BYV)为研究对象,首先利用"共沉淀-晶化"的方法制备了BYV固溶体纳米颗粒,随后利用压力诱导固溶体中四方相钒酸铋结构转变为单斜相,从而构建了BiVO₄/Bi_0.6Y_0.4VO₄复合光催化剂.XRD,Raman,HRTEM,HAADF-EDS的结果表明,经过高压后处理的BYV固溶体表面会出现粒径约为5 nm单斜钒酸铋纳米颗粒,实现了原位构建异质结结构.随后载流子动力学的相关表征以及Au选择性光沉积的结果表明,在光照条件下,所构建异质结中的光生电子主要分布在BYV固溶体上,而在表面形成的单斜相钒酸铋颗粒主要起到了类似"空穴"捕获的作用.这种在异质结中的载流子迁移路径符合S型异质结机理.电化学、稳态荧光光谱以及瞬态荧光光谱的表征结果表明,相比于单一固溶体,在S型异质结这种两步激发系统中所存在的载流子迁移路径能够大幅促进光生载流子分离,从而提高了小粒径BYV的光催化完全分解水性能.综上,构建S型异质结是一种解决小粒径光催化剂中载流子分离能力差的有效途径.同时,压力诱导材料晶型转变实现原位构建异质结的制备方法也为提高光生载流子分离效率提供了新的研究思路与机遇.     

Convergent architecting of multifunction-in-one hydrogels as wound dressings for surgical anti-infections

Surgical procedures are susceptible to the cause of infections, which could induce delayed wound healing, oxidative stress and tissue ischemia. Multifunctional wound dressings (e.g., hydrogels) without the induction of antibiotics is promising for the elimination of surgical site infections and the associated complications. Herein, we report a reductionism approach for the fabrication of bioactive hydrogels to recapitulate antibacterial functions as well as antioxidant, pro-angiogenic and hemostatic properties in surgical infection treatments. The hydrogels composed of naturally derived Cirsium setosum extracts (CE, a traditional medicinal herb) and carboxymethyl chitosan (CS) show their capacity for surgical anti-infections on three different models (i.e., infectious random skin flap model, infectious skin defect model and infectious femur fracture model). Due to the innate bioactivities of CE and CS, CECS hydrogels can also reduce the bleeding loss (85% reduction) on a hemorrhaging liver model and improve the vascularization for skin flap regeneration. Overall, bioactive CECS hydrogels integrated with the ease and scalability of assembly process and biological activities without the addition of antibiotics is promising to act as multifunctional wound dressings for surgical anti-infections.     

A modified finite element method for determining equilibrium capillary surfaces of liquids with specified volumes

This paper describes a modified finite element method (MFEM) for determining the static equilibrium shape of the capillary surface of a liquid with a prescribed volume constrained by rigid boundaries with arbitrary shapes. It is assumed that the liquid is in static equilibrium under the influence of surface tension, adhesion, and gravity forces. This problem can be solved by employing the conventional FEM; however, a major difficulty arises due to the presence of the volume (integral) constraint and usually requires the use of the Lagrange multiplier method, the sequential unconstrained minimization technique, or the augmented Lagrange multiplier method. With the MFEM, the space variables defining the equilibrium surfaces (or curves) are expanded in terms of parametric interpolation functions, which are designed such that the boundary conditions and the integral constraint equation are automatically satisfied during each iteration of a direct numerical search process. Hence, there is no need to include Lagrange multipliers and/or penalty factors and the problem can be treated more simply as one involving unconstrained optimization. This investigation indicates that the MFEM is more efficient and reliable than the other methods. Results are presented for several case study problems involving liquid solder drops. Copyright © 2000 John Wiley & Sons, Ltd.     

Back contact–absorber interface modification by inserting carbon intermediate layer and conversion efficiency improvement in Cu2ZnSn(S,Se)4 solar cell

Carbon layers have been employed as intermediate layers between Mo back contact and Cu₂ZnSn(S_1–xSe_x)₄(CZTSSe) absorber film prepared by sol–gel and post‐selenization method. Carbon layers with appropriate thickness can significantly inhibit the formation of MoSe₂ and voids at bottom region of the absorber, and therefore reduce the series resistance remarkably. The conversion efficiency can be boosted by the introducing of the carbon layer from 6.20% to 7.24% by enhancement in short current density, fill factor and open voltage in comparison to the reference sample without carbon layer. However, excess thickness of carbon layer will worse device performance due to the deteriorated absorber crystallinity. In addition, the time‐resolved photoluminescence analysis shows that inserting the carbon layer with suitable thickness does not introduce recombination and lower minority lifetime. (© 2015 WILEY‐VCH Verlag GmbH &Co. KGaA, Weinheim)