Surface‐Electron Coupling for Efficient Hydrogen Evolution

Maximizing the activity of materials towards the alkaline hydrogen evolution reaction while maintaining their structural stability under realistic working conditions remains an area of active research. Herein, we report the first controllable surface modification of graphene(G)/V₈C₇ heterostructures by nitrogen. Because the introduced N atoms couple electronically with V atoms, the V sites can reduce the energy barrier for water adsorption and dissociation. Investigation of the multi‐regional synergistic catalysis on N‐modified G/V₈C₇ by experimental observations and density‐functional‐theory calculations reveals that the increase of electron density on the epitaxial graphene enable it to become favorable for H* adsorption and the subsequent reaction with another H₂O molecule. This work extends the range of surface‐engineering approaches to optimize the intrinsic properties of materials and could be generalized to the surface modification of other transition‐metal carbides.     

Palladium Catalysis for Aerobic Oxidation Systems Using Robust Metal–Organic Framework

Described here is a new and viable approach to achieve Pd catalysis for aerobic oxidation systems (AOSs) by circumventing problems associated with both the oxidation and the catalysis through an all‐in‐one strategy, employing a robust metal–organic framework (MOF). The rational assembly of a Pd^II catalyst, phenanthroline ligand, and Cu^II species (electron‐transfer mediator) into a MOF facilitates the fast regeneration of the Pd^II active species, through an enhanced electron transfer from in situ generated Pd⁰ to Cu^II, and then Cu^I to O₂, trapped in the framework, thus leading to a 10 times higher turnover number than that of the homogeneous counterpart for Pd‐catalyzed desulfitative oxidative coupling reactions. Moreover, the MOF catalyst can be reused five times without losing activity. This work provides the first exploration of using a MOF as a promising platform for the development of Pd catalysis for AOSs with high efficiency, low catalyst loading, and reusability.     

Influence of lanthanum on morphology and electrochemical performance of nano-platinum-based catalytic membrane electrode

The current research of platinum (Pt)–based catalysts focuses on reducing Pt loading in the catalysts while enhancing the catalytic activity. As a rare-earth element, lanthanum (La) has demonstrated good synergistic effect with Pt-based catalysts, because of its catalytic promoting capability and high dispersibility. Here, we fabricated La-doped nano-Pt-based catalytic membrane electrode using ion beam sputtering method. The effect of La on the morphology and electrochemical performance of the catalytic membrane electrode was investigated by scanning electron microscope, X-ray photoelectron spectroscopy, and electrochemical measurements. Compared with pure Pt-based sample, the electrochemical activity specific area of the La-doped sample increases by 74.59%, with 63.95% increase in exchange current density. The results also show that La₂O₃ enhances oxygen enrichment of the membrane electrode and reduces interfacial energy among Pt grains while pinning the grain boundaries. In addition, the inductively coupled plasma atomic emission spectroscopy (ICP-AES) measurement shows that the Pt loading in the membrane electrodes is below 0.1 mg/cm². Thus, enhanced catalytic performance is achieved in catalysts with lower Pt loading.     

超高效液相色谱-三重四极杆质谱法测定人尿中9种邻苯二甲酸酯代谢物

建立了人尿中9种邻苯二甲酸酯（PAE）代谢物的超高效液相色谱-三重四极杆质谱（UPLC-MS/MS）测定方法。2 mL尿液样本酶解2 h后,经强阴离子固相萃取净化处理;选用Waters ACQUITY UPLC BEH Phenyl色谱柱（100 mm×2.1 mm,1.7 μ m）,以0.1%（体积分数）乙酸乙腈和0.1%（体积分数）乙酸水溶液为流动相进行梯度洗脱;在负离子电喷雾多反应监测模式（MRM）下测定9种PAE代谢物含量。8种PAE代谢物在0.39~200 μ g/L范围内、1种PAE代谢物在1.17~600 μ g/L范围内线性关系良好,相关系数均大于0.995。方法检出限为0.06~0.85 μ g/L,定量限为0.20~2.80 μ g/L。3个加标水平的加标回收率为84.1%~122%,精密度为4.5%~14.3%;日内精密度不高于9.3%,日间精密度不高于10.1%;基质效应和稳定性符合分析要求。应用该方法测定50份人尿液样本,邻苯二甲酸单环已酯（MCHP）和邻苯二甲酸单苄酯（MBZP）的检出率分别为0和44.0%,其余7种PAE代谢物的检出率为100%。该方法操作简单、定量准确、稳定性好,适用于人尿中9种PAE代谢物的定量分析。     

Molecular Modeling in Anion Exchange Membrane Research: A Brief Review of Recent Applications

Anion Exchange Membrane (AEM) fuel cells have attracted growing interest, due to their encouraging advantages, including high power density and relatively low cost. AEM is a polymer matrix, which conducts hydroxide (OH−) ions, prevents physical contact of electrodes, and has positively charged head groups (mainly quaternary ammonium (QA) groups), covalently bound to the polymer backbone. The chemical instability of the quaternary ammonium (QA)-based head groups, at alkaline pH and elevated temperature, is a significant threshold in AEMFC technology. This review work aims to introduce recent studies on the chemical stability of various QA-based head groups and transportation of OH− ions in AEMFC, via modeling and simulation techniques, at different scales. It starts by introducing the fundamental theories behind AEM-based fuel-cell technology. In the main body of this review, we present selected computational studies that deal with the effects of various parameters on AEMs, via a variety of multi-length and multi-time-scale modeling and simulation methods. Such methods include electronic structure calculations via the quantum Density Functional Theory (DFT), ab initio, classical all-atom Molecular Dynamics (MD) simulations, and coarse-grained MD simulations. The explored processing and structural parameters include temperature, hydration levels, several QA-based head groups, various types of QA-based head groups and backbones, etc. Nowadays, many methods and software packages for molecular and materials modeling are available. Applications of such methods may help to understand the transportation mechanisms of OH− ions, the chemical stability of functional head groups, and many other relevant properties, leading to a performance-based molecular and structure design as well as, ultimately, improved AEM-based fuel cell performances. This contribution aims to introduce those molecular modeling methods and their recent applications to the AEM-based fuel cells research community.     

Structure Dependence of Fe‐Co Hydroxides on Fe/Co Ratio and Their Application for Supercapacitors

Fe‐Co hydroxides with different Fe/Co atomic ratios grown on nickel foams are synthesized by one‐step electrochemical deposition. The prepared samples are characterized by X‐ray diffraction, X‐ray photoelectron spectroscopy, scanning electron microscopy, and transmission electron microscopy. It was found that the influence of initial Fe/Co ratios in the precursor solutions on the structure and electrochemical performance of electrodeposited products is significant. Fe(OH)₃ shows particle shape with average diameter of 200 nm. With addition of Co ions, frame‐like structure consisting of smaller particles is formed for Fe‐Co hydroxides. Based on the morphology of Co(OH)₂, it is deduced that Co(OH)₂ serves as a network former constructing a tridimensional frame network structure. Fe‐Co hydroxide with Fe/Co ratio of 1:1 exhibits two types of structure features: nanoflake‐like network structure overall and nanoparticle structure with numerous mesoporous microscopically. As the supercapacitor electrode materials, the as‐prepared Fe‐Co hydroxide electrode with Fe/Co ratio of 1:1 exhibits highest specific capacitance of 2255.6 F g^?1 at the current density of 1 A g^?1 and also shows good cycling performance of 73.5% capacity retention at current density of 10 A g^?1 after 2000 cycles. This work provides a facile method to produce promising Fe‐Co hydroxide electrode materials with high performance for supercapacitors.     

高铁酸钾的制备及其在废水治理中的应用进展

高铁酸钾是一种集氧化、絮凝、吸附、杀菌、消毒、除臭功能于一体的新型绿色高效水处理药剂,在废水处理领域具有重要的理论研究和实际应用价值.本文对近年来高铁酸钾的制备方法及其在废水治理中的应用进行综述,重点分析了各制备方法的优缺点,并结合当前最新研究成果对高铁酸钾的工业制备及在废水治理中的应用前景进行了展望.     

Effects of magnetic annealing on structure and multiferroic properties of pure and dysprosium substituted BiFeO3

In this work, the effects of magnetic annealing on crystal structure and multiferroic properties of BiFeO₃ and Bi_0.85Dy_0.15FeO₃ have been investigated. It is found that the X-ray diffraction patterns of pure BiFeO₃ samples are obviously broadened after magnetic annealing, whereas those of Bi_0.85Dy_0.15FeO₃ samples are almost unchanged. Magnetic field annealing did not affect the magnetic properties of these two kinds of samples much. However, ferroelectric properties of the two materials exhibited different behaviors after magnetic field annealing. For pure BiFeO₃ samples, the remnant polarizations (P_r) are suppressed; in contrast, for Bi_0.85Dy_0.15FeO₃ samples, P_r is greatly enhanced. Possible mechanisms for the effects of magnetic field annealing have been discussed.     

非瑞利海洋混响抑制技术研究

随着主动声呐距离及角度分辨率的提高,海洋混响包络概率密度函数不再是瑞利分布,而是函数分布后端较瑞利分布具有严重拖尾性的非瑞利分布。但非瑞利分布模型的概率密度函数复杂,参数估计困难。通过对非瑞利分布混响进行恒虚警率检测处理,将严重拖尾部分数据值衰减为背景均值,从而将非瑞利分布混响信号转化为近似瑞利分布。由于去掉了对背景功率估计影响较重的干扰,并基于瑞利分布模型进行目标检测,本文目标检测方法具有较好的鲁棒性和计算简单等优点。文中对一组高分辨率声呐数据进行了恒虚警率检测,结果验证了方法的有效性。     

液液萃取-高分辨气相色谱-高分辨双聚焦磁质谱法测定尿中羟基多环芳烃代谢物

建立了灵敏、准确的液液萃取-高分辨气相色谱-高分辨双聚焦磁质谱(LLC-HRGC-HRMS)同时测定人体尿样中8种多环芳烃(PAHs)代谢物的方法。将2 mL尿液与氘或¹³C标记的同位素内标物进行混合,在抗坏血酸的存在下酶解偶联目标物,再将游离化合物用甲苯-戊烷(1∶4, v/v)萃取后浓缩至近干,再用甲苯复溶,衍生后经HRGC-HRMS分离和测定。1-羟基萘在0.14～41.6μg/L、1-羟基菲在0.05～8.33μg/L、2-羟基菲在0.04～8.33μg/L、其他5种代谢产物在0.02～8.33μg/L范围内线性关系良好,相关系数>0.99,方法的检出限为0.006～0.042μg/L,平均回收率为81.4%～127.0%,日内和日间精密度分别为2.7%～6.9%和5.1%～10.9%(n=6)。应用该方法测定330份人群尿液样本,3-羟基■和6-羟基■未检出,其他6种PAHs代谢物检出率为100%。该方法灵敏、准确、稳定,适用于人尿中8种PAHs代谢物的定量分析。