Single-atom Fe Embedded Co3S4 for Efficient Electrocatalytic Oxygen Evolution Reaction

Constructing atomically dispersed active sites with densely exposed and dispersed double metal-S_x catalytic sites for favorable OER catalytic activity remains rare and challenging. Herein, we design and construct a Fe₁S_x@Co₃S₄ electrocatalyst with Fe single atoms epitaxially confined in Co₃S₄ nanosheets for catalyzing the sluggish alkaline oxygen evolution reaction(OER). Consequently, in ultralow concentration alkaline solutions(0.1 mol/L KOH), such a catalyst is highly active and robust for OER with low overpotentials of 300 and 333 mV at current densities of 10 and 30 mA/cm², respectively, accompanying long-term stability without significant degradation even for 350 h. In addition, Fe₁S_x@Co₃S₄ shows a turnover frequency(TOF) value of 0.18 s⁻¹, nearly three times that of Co₃S₄(0.07 s⁻¹), suggesting the higher atomic utilization of Fe single atoms. Mössbauer and in-situ Raman spectra confirm that the OER activity of Fe₁S_x@Co₃S₄ origins from a thin catalytic layer of Co(Fe)OOH that interacts with trace-level Fe species in the electrolyte, creating dynamically stable active sites. Combined with experimental characterizations, it suggests that the most active S-coordinated dual-metal site configurations are 2S-bridged (Fe-Co)S₄, in which Co-S and Fe-S moieties are shared with two S atoms, which can strongly regulate the adsorption energy of reaction intermediates, accelerating the OER reaction kinetics.     

Density Functional Theory Mechanistic Study of Boron‐Catalyzed N‐Alkylation of Amines with Formic Acid: Formic Acid Activation by Silylation Reaction

New methodology for the alkylation of amines is an intriguing issue in both academia and industry. Recently, several groups reported the metal‐free B(C₆F₅)₃‐catalyzed N‐alkylation of amines, but the mechanistic details of these important reactions are unclear. Herein, a computational study was performed to elucidate the mechanism of the N‐alkylation of amines with formic acid catalyzed by the Lewis acid B(C₆F₅)₃ in the presence of hydrosilane. We found that the reaction started with the activation of formic acid through a novel model. Then, the high electrophilicity of the C center of the formic acid unit and the nucleophilic character of the amine resulted in a C?N coupling reaction. Finally, two sequential silyl‐group and H^? transfer steps occurred to generate the final product. Upon comparing the reaction barrier and the hydrogenation of indole, our mechanism is more favorable than that proposed by the group of Yu and Fu.     

配合物[Co(Hdhpmy)(H2O)3]·3H2O的合成、晶体结构和荧光性质

用溶液法合成了钴的配合物[Co(Hdhpmy)(H₂O)₃]·3H₂O(H₃dhpmy=4,6-二羟基嘧啶-2-硫醇乙酸),对它进行了元素分析、红外光谱、荧光等表征,并用X-射线单晶衍射测定了配合物的单晶结构。标题配位聚合物晶体属正交晶系,Pca2₁空间群。弱的π-π相互作用将单分子连接成一维链状结构,而氢键使配合物形成三维网状结构。     

Strict Mittag-Leffler Conditions and Gorenstein Modules

In this paper, firstly, we characterize some rings by strict Mittag-Leffler conditions. Then, we investigate when Gorenstein projective modules are Gorenstein flat by employing tilting modules and cotorsion pairs. Finally, we study the direct limits of Gorenstein projective modules.     

Fluorescent-tagged block copolymer as an effective and green inhibitor for calcium sulfate scales

Allyloxy polyethoxy ether (APEG) and succinic anhydride were used to prepare allyloxy polyethoxy carboxylate (APEL). 8-Hydroxy-1,3,6-pyrene trisulfonic acid trisodium salt (PY) was reacted with allyl chloride to produce fluorescent monomer 8-allyloxy-1,3,6-pyrene trisulfonic acid trisodium salt (PA). APEL and PA were copolymerized with maleic anhydride (MA) to synthesize PA tagged no phosphate and nitrogen free CaSO₄ inhibitor MA–APEL–PA. Structures of PA, APEG, APEL, and MA–APEL–PA were identified by ¹H NMR. The observation shows that the dosage of MA–APEL–PA plays an important role on CaSO₄ inhibition. The effect on formation of CaSO₄ was investigated with scanning electron microscope (SEM) analysis. Relationship between MA–APEL–PA’s fluorescent intensity and its dosage was studied. Correlation coefficient R ² of MA–APEL–PA fluorescent intensity and MA–APEL–PA dosage is 0.9991.     

室内MIMO可见光通信的接收特性

建立了一种基于MIMO的室内二次反射可见光通信的信道模型。通过模型仿真,从不同位置处接收面上探测器的不同间距、不同面积以及接收面横向、纵向旋转方面,分析了室内MIMO可见光通信的接收特性。仿真结果表明,在满足信号可恢复的条件下,接收面探测器间距d的变化对光信号接收的影响很小,不同接收位置的接收信噪比(SNR)也呈现不同的分布。另外,接收面横向旋转不会影响光信号接收,而纵向旋转具有一定的限制范围。     

Convergence of the variants of the Chebyshev–Halley iteration family under the Hölder condition of the first derivative

The present paper is concerned with the convergence problem of the variants of the Chebyshev–Halley iteration family with parameters for solving nonlinear operator equations in Banach spaces. Under the assumption that the first derivative of the operator satisfies the Hölder condition of order p$p$, a convergence criterion of order 1+p$1+p$ for the iteration family is established. An application to a nonlinear Hammerstein integral equation of the second kind is provided.     

关注学科知识的职前化学教师自主研修——基于“化学师范生备课组”的活动个案

学科知识是师范生专业素质的重要组成部分,研究基于化学师范生备课组以学科知识强化为主题的研修活动,从备课选题、研修过程、问题批判等方面探讨化学师范生学科知识强化新途径,评析化学师范生备课组的价值。     

依据强非局域介质中光孤子相互作用实现全光互联

根据强非局域介质构成的平面介质波导中同频率和同极化的多光束共同传输模型方程,求得了任意斜入射多光束相互作用的精确解析解。基于强非局域介质空间双光孤子的相互作用原理,提出了利用全同孤子作为信号光来实现全光互联,但实现的逻辑也仅仅局限于短距离作用,还对全光开关抑或反相器作了详细叙述,通过实例给出了这类设计的优化方案。     

Probing Quark Loop Effects on Dressed Gluon Propagator

We study the quark loop effects on the dressed gluon propagator and also on the quark propagator itself. We find that the gluon propagators are different in two phases. The quark mass effects on the gluon propagator are small but not negligible. We also study the current quark mass dependence on the bag constant.