Tuning the Composition and Structure of Ni@MoC Nanosheets for Highly Active and Stable Electrocatalysis in Water Splitting

The conventional electrolytic water-splitting process for hydrogen production is plagued by high energy consumption, low efficiency, and the requirement of expensive catalysts. Therefore, finding effective, affordable, and stable catalysts to drive this reaction is urgently needed. We report a nanosheet catalyst composed of carbon nanotubes encapsulated with MoC/Mo₂C, the Ni@MoC-700 nanosheet showcases low overpotentials of 275 mV for the oxygen evolution reaction and 173 mV for the hydrogen evolution reaction at a current density of 10 mA ⋅ cm⁻². Particularly noteworthy is its outstanding performance in a two-electrode system, where a cell potential of merely 1.64 V is sufficient to achieve the desired current density of 10 mA ⋅ cm⁻². Furthermore, the catalyst demonstrates exceptional durability, maintaining its activity over a continuous operation of 40 hours with only minimal attenuation in overpotential. These outstanding activity levels and long-term stability unequivocally highlight the promising potential of the Ni@MoC-700 catalyst for large-scale water-splitting applications.     

无粘结剂ZSM-11催化剂上异丁烯直接胺化生成叔丁胺

叔丁胺是一种重要的化工原料和中间体,广泛应用于制备橡胶促进剂、医药、农药和着色剂等下游产品.异丁烯在分子筛催化剂上直接胺化生产叔丁胺是一个经济环保过程,其中ZSM-5和BEA分子筛的催化性能优于其它系列分子筛.ZSM-11与ZSM-5分子筛具有相似的孔道结构,我们以前的实验结果表明,与ZSM-5相比,ZSM-11表现出更优越的芳构化反应性能,在干气中乙烯低温芳构化方面也有明显优势.在此基础上,我们进行无粘结剂ZSM-11分子筛催化剂合成,并应用于异丁烯直接胺化生产叔丁胺反应.传统水热技术合成的分子筛通常为粉末,机械强度不能达到实际应用的要求,在工业化过程中分子筛粉末一般需要加入粘结剂成型使其具备一定的机械强度和形状,但是粘结剂会降低分子筛催化剂的活性和选择性,有可能会引发一些副反应,因此无粘结剂分子筛催化剂引起人们广泛关注.无粘结剂分子筛是指分子筛颗粒中不含惰性粘结剂或只含有少量粘结剂,主要依靠分子筛晶粒间的相互作用支撑存在,具有一定形状、尺寸和机械强度的催化材料.无粘结剂分子筛催化剂中分子筛含量较高,可利用的有效表面积较大,在离子交换及工业催化等方面具有明显优势.本文采用水热合成的ZSM-11分子筛原粉与二氧化硅机械混合(ZSM-11/SiO2=70/30)挤条后,通过气固相合成法制备了无粘结剂ZSM-11分子筛催化剂(Cat-C).作为对比,还分别制备了ZSM-11和SiO2机械混合(ZSM-11/SiO2=70/30)样品HZSM-11+SiO2及ZSM-11和氧化铝机械混合(ZSM-11/Al2O3=70/30)样品HZSM-11+Al2O3.利用X射线衍射、透射电镜、NH3程序升温脱附和吸附吡啶红外光谱等对分子筛催化剂的物理化学性能进行了表征.同时,以这些分子筛样品为催化剂,在固定床反应装置上进行了异丁烯胺化反应评价,反应条件为270℃,5.0 MPa,氨烯比为4和异丁烯空速0.5 h?1.结果表明,与HZSM-11+SiO2和HZSM-11+Al2O3相比,Cat-C上叔丁胺生成速率最高.关联催化剂物化性能和反应性能发现,催化剂孔道结构与叔丁胺生成并不存在明显的关联性,而较多的Br?nsted酸和较少的Lewis酸才是Cat-C具有良好反应性能的主要原因.具有一定机械强度的无粘结剂ZSM-11分子筛催化剂制备简单,在异丁烯直接胺化过程中叔丁胺生成速率高,具有很好的工业化应用前景.     

Photo-induced synthesis and in vitro biological activity of a Sansalvamide A analog

Photoinduced single electron transfer (SET) cyclization processes for synthesis of a Sansalvamide A analog containing double pharmacophores (cyclicpeptides and O-phthalimide moiety) is described to develop novel antitumor cyclopeptide drug. The resultant compound is active in drug-sensitive HeLa, HepG-2 and MCF-7 cell lines. Specifically, the title compound was found to inhibit MCF-7 cells with an IC₅₀ value of 15 μM (13.4 μg/mL), which may serve as a potential candidate for antitumor drug development.     

The global stability and pattern formations of a predator–prey system with consuming resource

The paper deals with a model that describes a predator–prey system with a common consuming resource. We use Lyapunov functions to prove the global stability of the kinetic system and the diffusive system. The existence of non-constant positive steady state solutions is shown to identify the range of parameters of spatial pattern formation for the cross-diffusion system.     

Shaped binderless ZSM-11 zeolite catalyst prepared via a dry-gel conversion method:Characterization and application for alkylation of benzene with dimethyl ether

Shaped binderless ZSM-11 zeolite catalysts were synthesized via a dry-gel conversion technique from 70ZSM-11/30 SiO_2mix extrudates. 1,6-hexanediamine combined with tetrabutylammonium bromide was proved to be the best structure directing agent for the synthesis of the binderless ZSM-11 catalyst, without adding other alkaline materials. The 70HZSM-11/30 SiO_2mix serials materials crystallized for different times were detected by X-ray diffraction(XRD), nuclear magnetic resonance(NMR), scanning electron microscopy(SEM), transmission electron microscopy(TEM), scanning transmission electron microscopy–energy dispersive spectroscopy(STEM–EDS) techniques, and so on. In order to investigate the possible crystallization mechanism, the textural and structural properties of 70HZSM-11/30 SiO_2mix serials samples were further characterized by N_2 adsorption–desorption. Acid properties were determined by temperature-programed desorption of NH_3(NH_3-TPD) and pyridine adsorption-infrared(Py-IR) measurements. In the alkylation of benzene with dimethyl ether, the serials catalysts exhibited different benzene conversions. 70HZSM-11/30 SiO_2mix showed the lowest benzene conversion while sample 70HZSM-11/30 SiO_2mix-6.5h synthesized only for 6.5h displayed a higher benzene conversion, even higher than the value over 70HZSM-11/30Al_2O_3mix. Extending the crystallization time, the obtained samples displayed the increased benzene conversion in general under the same reaction conditions. In the end, the relation of physicochemical properties with the reaction performance was investigated.     

(Pr0.9La0.1)2(Ni0.74Cu0.21Ga0.05)O4+δ-Ce0.9Gd0.1O2-δ复合阴极的制备及电化学性质

采用EDTA-柠檬酸盐法制备了（Pr_0.9La_0.1）₂（Ni_0.74Cu_0.21Ga_0.05）O_4+δ（PLNCG）,并与Ce_0.9Gd_0.1O_2-δ（CGO）形成复合阴极PLNCG-CGO。XRD和SEM分析结果表明PLNCG与CGO在1 000℃具有较好的化学相容性。电化学阻抗测试结果表明PLNCG-30% CGO复合阴极在700℃的极化电阻为0.092 Ω·cm²;过电位为39.3 mV时,电流密度达到113.3 mA·cm^-2。氧分压分析表明电极反应的速率控制步骤为电荷转移过程。阳极支撑单电池（Ni-CGO/CGO/PLNCG-30% CGO）在700℃的最大输出功率密度达到569 mW·cm^-2,开路电压（OCV）为0.76 V。综上结果预示PLNCG-30% CGO复合阴极是一种有发展前景的电极材料。     

Defect induced paramagnetism in lightly doped ZnS:Fe nanoparticles

Nanoparticles of ZnS:Fe (0, 1, 3, and 5 at%) were synthesized by a refluxing route at 80 °C. All the samples exhibited cubic structure as revealed by X-ray powder diffraction studies. Blue emission of undoped samples was totally quenched by Fe doping. Magnetic measurements showed that the undoped ZnS was diamagnetic whereas all the doped samples were paramagnetic at room temperature. EPR signal characteristic of Fe³⁺ was observed in all the doped samples at room temperature. The paramagnetism of the present samples is attributed to the presence of uncoupled Fe³⁺ ions mediated by cation vacancies.     

Reproducing Kernel method for the solution of nonlinear hyperbolic telegraph equation with an integral condition

In this article, an iterative method is proposed for solving nonlinear hyperbolic telegraph equation with an integral condition. Its exact solution is represented in the form of series in the reproducing kernel space. In the mean time, the n‐term approximation u_n(x, t) of the exact solution u(x, t) is obtained and is proved to converge to the exact solution. Moreover, the partial derivatives of u_n(x, t) are also convergent to the partial derivatives of u(x, t). Some numerical examples have been studied to demonstrate the accuracy of the present method. Results obtained by the method have been compared with the exact solution of each example and are found to be in good agreement with each other. © 2010 Wiley Periodicals, Inc. Numer Methods Partial Differential Eq 27: 867–886, 2011     

Single atom entropy squeezing for two two-level atoms interacting with a binomial field

In this paper we consider a system of two two-level atoms interacting with a binomial field in an ideal cavity. We investigate the time evolution of the single atom entropy squeezing, atomic inversion and the linear entropy for the present system. Furthermore, the relationship between the entropy squeezing and the entanglement is investigated. It is shown that the amounts of the nonclassical effects exhibited in the entropy squeezing are dependent on the different initial conditions. The entropy squeezing can give information on the corresponding linear entropy.     

Rapid microwave-assisted synthesis and electrochemical characterization of gold/carbon nanotube composites

Hybrid nanostructures composed of gold nanoparticles (NPs) and carbon nanotubes (CNTs) have been prepared by a microwave-assisted method in the mixed solvents of oleylamine and oleic. The morphology, structure and composition of as-obtained Au/CNT composites are characterized by transmission electron microscopy (TEM), energy dispersive X-ray spectroscopy (EDS), X-ray diffraction (XRD). The composites show characteristic plasmon absorption of Au NPs in the Ultraviolet–visual spectrum. Fourier transform infrared spectrum shows the successful introduction of functional groups on the surface of CNTs, which are crucial factors to assist the nucleation in situ of Au NPs on the surface of CNTs. Electrochemical measurements show the enhancement electrochemical response for the gold electrode modified with Au/CNT composites.