Cyclodextrin-supported Co(OH)2 Clusters as Electrocatalysts for Efficient and Selective H2O2 Synthesis

Co-based material catalysts have shown attractive application prospects in the 2 e⁻ oxygen reduction reaction (ORR). However, for the industrial synthesis of H₂O₂, there is still lack of Co-based catalysts with high production yield rate. Here, novel cyclodextrin-supported Co(OH)₂ cluster catalysts were prepared via a mild and facile method. The catalyst exhibited remarkable H₂O₂ selectivity (94.2 % ~ 98.2 %), good stability (99 % activity retention after 35 h), and ultra-high H₂O₂ production yield rate (5.58 mol g_catalyst⁻¹ h⁻¹ in the H-type electrolytic cell), demonstrating its promising industrial application potential. Density functional theory (DFT) reveals that the cyclodextrin-mediated Co(OH)₂ electronic structure optimizes the adsorption of OOH* intermediates and significantly enhances the activation energy barrier for dissociation, leading to the high reactivity and selectivity for the 2 e⁻ ORR. This work offers a valuable and practical strategy to design Co-based electrocatalysts for H₂O₂ production.     

Synthesis of Sn nanocluster@carbon dots for photodynamic therapy application

Recently, photodynamic therapy (PDT) has been extensively applied in clinical and coadjuvant treatment of various kinds of tumors. However, the photosensitizer (PS) of PDT still lack of high production of singlet oxygen (¹O₂), low cytotoxicity and high biocompatibility. Herein, we propose a facile method for establishing a new core-shell structured Sn nanocluster@carbon dots (CDs) PS. Firstly, Sn⁴⁺@S-CDs complex is synthesized using the sulfur-doped CDs (S-CDs) and SnCl₄ as raw materials, and subsequently the new PS (Sn nanocluster@CDs) is obtained after vaporization of Sn⁴⁺@S-CDs solution. Remarkably, the obtained Sn nanocluster@CDs show an enhanced fluorescence as well as a higher ¹O₂ quantum yield (QY) than S-CDs. The high ¹O₂ QY (58.3%) irradiated by the LED light (400–700 nm, 40 mW/cm²), induce the reduction of 4T1 cancer cells viability by 25%. More intriguingly, no visible damage happens to healthy cells, with little impact on liver tissue due to renal excretion, both in vitro and in vivo experiments demonstrate that Sn nanocluster@CDs may become a promising PS, owning a high potential for application in PDT.     

Magnetic properties and formation of Sr ferrite nanoparticle and Zn,Ti/Ir substituted phases

Strontium hexaferrite nanoparticles are prepared by the chemical sol–gel route. Specific saturation magnetization σ_s and coercive field strength H_c are determined depending on the heat treatment of the gel and iron/strontium ratio in the starting solution. These ultrafine powders with single-domain behavior have specific saturation magnetization σ_s=74 emu/g and coercive field strength H_c=6.4 kOe. Experimental results show that it is necessary to preheat the gel between 400 and 500°C for several hours . It can prevent the formation of intermediate γ-Fe₂O₃ and help to obtain ultrafine strontium ferrite single phase with narrow size distribution at a low annealing temperature. Additionally, the magnetic properties of sol–gel derived strontium ferrite with iron substituted by Zn²⁺, Ti⁴⁺ and Ir⁴⁺ are discussed. For an amount of substitution 0<x⩽0.6, the (Zn, Ti)_x substituted strontium ferrite shows higher values of both coercive field strength and saturation magnetization than the (Zn, Ir)_x substituted phase.     

A long-standing structural puzzle resolved: the crystal structure of [Ag2(TpMe,Me)2] [where TpMe,Me is hydrotris(3,5-dimethyl-pyrazolyl)borate]

The crystal structure of the simple 1:1 complex of Ag(I) with hydrotris(3,5-dimethylpyrazolyl)borate (Tp^Me,Me) has been shown to be an asymmetric dimer, in which each Tp^Me,Me ligand bridges both metals by coordinating two pyrazolyl donors to one Ag(I) centre and one to the other, such that to a first approximation one Ag(I) is four coordinate and the other is two coordinate. However two of the pyrazolyl donors around the `four-coordinate' metal centres are also involved in weak, asymmetric bridging interactions with the `two-coordinate' metal centres. This is in contrast to the structure of the Cu(I) analogue [Cu₂(Tp^Me,Me)₂] in which both Cu(I) ions are three coordinate.     

1.653 μm处甲烷分子谐波探测技术研究

谐波探测被广泛应用于激光光谱技术中,利用它可以提高探测灵敏度。利用1.653 μm的分布反馈式(DFB)二极管激光器作为光源,建立了一套可调谐半导体激光吸收光谱(TDLAS)甲烷探测装置。该装置利用由2块圆形柱面镜构成的光学多通池增加吸收光程,提高探测灵敏度。吸收池基长为15 cm,在112次反射情况下,有效吸收光程达到16.8 m,实现甲烷0.60×10-6(2 s采样时间)的探测极限,可应用于实际大气甲烷的痕量探测。     

Transformations of the stepped Si(001) surface structure induced by heating the specimen by a current

The system of uniformly distributed atomic steps on a vicinal Si(001) surface was observed to transform into a system of large terraces, separated by step bands, when the specimen is heated by a direct electric current. This transformation is reversible and depends on the current direction and the initial step density. The experimental data are discussed in terms of electromigration of adatoms.     

Oblique indentation of creeping solids

Oblique indentation of power law creeping solids at plane strain conditions is examined with rigid-perfectly plastic material behaviour emerging as an asymptotic case. Indenter profiles are dealt with in general circumstances and represented by homogeneous functions. The core of the method developed draws on self-similarity and is based on an intermediate flat die solution. By this approach the problem of a moving contact boundary may be suppressed and the ensuing procedure becomes independent of loading, geometry, history and time. A computational method, based on the reduced procedure, is developed to obtain high accuracy solutions based on finite elements and applicable to non-linear elasticity. The originally stated problem is then solved subsequently by simple cumulative superposition and results given as a function of impression depth. The relation between contact depth and area is found to be invariant and only dependent on the power law exponent, the amount of friction, the profile and the angle of inclination of the indenter. Detailed results are given for local states of stress and deformation for flat and cylindrical dies at variation of the remaining three stated parameters. The presence of local stick and slip is given due attention and global relations between loading and indentation depth and contact area discussed for practical applications. The fundamental framework laid down may be applied to structural assemblies, joints and seals and diverse applications as flattening of rough surfaces, compaction of powder aggregates and ice-offshore structure interaction.     

Pd单原子/团簇高效催化铃木偶联反应

铃木偶联反应是合成聚烯烃、苯乙烯和联苯衍生物等功能性有机化合物的有力工具,广泛应用于精细化工、制药和生化工业领域.钯(Pd)基催化剂是目前性能最好的铃木偶联反应催化剂,但钯的低丰度和高成本限制了其大规模应用.因此,提高Pd原子的利用效率,降低Pd用量至关重要.减小金属纳米粒子的尺寸,使其成为小团簇甚至孤立的金属原子是实...     

Static and dynamic quadrupole moments of high-spin isomers in the Pb-region

Quadrupole moments of high-spin isomers in the Pb-region are studied by using core polarization charges induced by the coupling of single-particle states to giant resonances. We found that the core polarization charges are enough to reproduce the observed quadrupole moments of the isotones with neutron number N=126 quantitatively without any intrinsic deformation. The mass number dependence of the quadrupole moments in the Rn-isotopes is also discussed by taking into account the configuration mixing involving the neutron excited first 2⁺ state.     

氧化钙薄膜中缺陷诱导的高居里温度铁磁性研究

通过脉冲激光沉积在(111)取向钇稳定的氧化锆(YSZ)衬底上制备了氧化钙(CaO)薄膜.室温下磁滞回线的实验观测数据表明CaO薄膜具有明显的铁磁性.X射线衍射和X射线光电子能谱分析表明,CaO薄膜为(111)取向,没有杂质相.在高真空条件下生长和退火的CaO薄膜都表现出铁磁性磁化行为,而在相应的CaO靶材上没有检测到...