Improved Electrocatalytic Activity and Stability by Single Iridium Atoms on Iron-based Layered Double Hydroxides for Oxygen Evolution

Full understanding to the origin of the catalytic performance of a supported nanocatalyst from the points of view of both the active component and support is significant for the achievement of high performance. Herein, based on a model electrocatalyst of single-iridium-atom-doped iron (Fe)-based layered double hydroxides (LDH) for oxygen evolution reaction (OER), we reveal the first completed origin of the catalytic performance of such supported nanocatalysts. Specially, besides the activity enhancement of Ir sites by LDH support, the stability of surface Fe sites is enhanced by doped Ir sites: DFT calculation shows that the Ir sites can reduce the activity and enhance the stability of the nearby Fe sites; while further finite element simulations indicate, the stability enhancement of distant Fe sites could be attributed to the much low concentration of OER reactant (hydroxyl ions, OH⁻) around them induced by the much fast consumption of OH⁻ on highly active Ir sites. These new findings about the interaction between the main active components and supports are applicable in principle to other heterogeneous nanocatalysts and provide a completed understanding to the catalytic performance of heterogeneous nanocatalysts.     

Eutectic-Based Polymer Electrolyte with the Enhanced Lithium Salt Dissociation for High-Performance Lithium Metal Batteries

The deployment of lithium metal anode in solid-state batteries with polymer electrolytes has been recognized as a promising approach to achieving high-energy-density technologies. However, the practical application of the polymer electrolytes is currently constrained by various challenges, including low ionic conductivity, inadequate electrochemical window, and poor interface stability. To address these issues, a novel eutectic-based polymer electrolyte consisting of succinonitrile (SN) and poly (ethylene glycol) methyl ether acrylate (PEGMEA) is developed. The research results demonstrate that the interactions between SN and PEGMEA promote the dissociation of the lithium difluoro(oxalato) borate (LiDFOB) salt and increase the concentration of free Li⁺. The well-designed eutectic-based PAN_1.2-SPE (PEGMEA: SN=1: 1.2 mass ratio) exhibits high ionic conductivity of 1.30 mS cm⁻¹ at 30 °C and superior interface stability with Li anode. The Li/Li symmetric cell based on PAN_1.2-SPE enables long-term plating/stripping at 0.3 and 0.5 mA cm⁻², and the Li/LiFePO₄ cell achieves superior long-term cycling stability (capacity retention of 80.3 % after 1500 cycles). Moreover, Li/LiFePO₄ and Li/LiNi_0.6Co_0.2Mn_0.2O₂ pouch cells employing PAN_1.2-SPE demonstrate excellent cycling and safety characteristics. This study presents a new pathway for designing high-performance polymer electrolytes and promotes the practical application of high-stable lithium metal batteries.     

丙三醇存在下硫酸钡微粒体系的光谱特性研究及其分析应用

0.10 mol/L HCl-4.0 mol/L丙三醇-0.05 mol/L BaCl2溶液体系的瑞利散射很弱.当有SO4^2-存在时,（BaSO4）n微粒体系在470 nm处产生一较强的瑞利散射峰,SO4^2-浓度在1.0～80μg/mL浓度范围内与I470nm呈线性关系.据此,建立了一个测定水中硫酸根的简便、灵敏的瑞利散射光谱分析新方法.研究结果表明：SO4^2-与Ba^2＋由于静电引力可形成BaSO4分子,而BaSO4分子间存在较强疏水作用力和分子间作用力,可聚集形成（BaSO4）n微粒和固液界面,（BaSO4）n微粒和固液界面的形成是导致体系瑞利散射强的根本原因.     

火焰原子吸收光谱法测定高铝锌基合金中的镁

提出了用火焰原子吸收光谱法测定高铝锌基合金中镁的方法,在测定条件下,共存元素的干扰可消除,能测定高铝锌基金合中0．001－0．01％,范围内的镁,该方法相对标准偏差＜6％,样品加标回收率为94－102％。     

Simple and robust digital holography for high-resolution imaging

Based on the point spread function of holographic system,the lateral resolution of digital holographic imaging system without any pre-magnification is studied.The expression of resolution limitation of holographic imaging system is thus presented.We investigate the possibilities to improve the lateral resolution.The simple experimental setup with an off-axis arrangement is built.By using a U.S.Air Force(USAF)test target as microscopic object,the recorded holograms are reconstructed digitally based on the principle of Fresnel diffraction.The lateral resolution of 2.76 μm without any pre-magnification is demonstrated experimentally,which matches the theoretical prediction well.     

Closely packed dense frequency selective surface

In order to realize wideband filtering properties of frequency selective surface （FSS）, FSS of closely packed elements is presented. The Y loop elements are chosen as the graphics elements. Based on the spectral domain method, the frequency response is analyzed for different incident angles and polarizations. The result of the numerical analysis shows that the dense FSS has wide passband with better independence of angle and polarization.     

A Chiral Helical Compound Based on Achiral Components

The title compound, [Cu(dpa)(2,2'-bipy)(H2O)2]n 1 (H2dpa = diphenic acid and 2,2'- bipy = 2,2'-bipyridine), has been synthesized and its structure was determined by single-crystal X-ray diffraction. The crystal is of orthorhombic, space group P212121 with a = 10.597(4), b = 11.317(4), c = 17.630(7) , V = 2114.3(14) 3, C24H20CuN2O6, Mr = 495.97, Z = 4, Dc = 1.558 g/cm3, μ = 1.079 mm-1, F(000) = 1020, Flack value = 0.052(18), R = 0.0430 and wR = 0.1016 for 3381 observed reflections (I > 2σ(I)). In compound 1, the dpa ligands link metal ions into helical structures in the same direction.     

A Polymeric Iodiplumbate(Ⅱ) Templated by Conjugated Quaternary Ammonium: Synthesis, Band Structure and Optical Properties

A new lead(Ⅱ) iodide coordination polymer [(npq)(PbI3)]n 1 (npq = N-propyl- quinolinium) has been synthesized in the presence of npq as structure-directing reagent (SDA). Compound 1 crystallizes in the orthorhombic system, space group Pbca, with a = 19.158(4), b = 7.9909(16), c = 22.929(5) (A), V = 3510.2(12) (A)3, Z = 8, Dc = 2.877 g/cm3, F(000) = 2672, C12H14I3NPb, Mr = 760.14, μ(MoKα) = 14.872 mm-1, the final R = 0.0431 and wR = 0.1021 for 3678 observed reflections with I＞2σ(I). Structure determination indicates that the [PbI3]-n infinite chains in each unit cell shape the sketch of 1, which could be described as the result of face-sharing distorted PbI6 octahedra running along the b axis. Electrostatic interaction between conjugated organic counter-cations and inorganic moieties presents and contributes to the crystal packing. 1 was further characterized with IR and elemental analysis. Based on the crystal structure data, quantum chemical calculation with DFT method was used to reveal the electronic structure and optical property of 1.     

DETERMINATION OF DEGREE OF CRYSTALLINITY OF NYLON 1212 BY WIDE-ANGLE X-RAY DIFFRACTION

Based on the X-ray scattering intensity theory and using the approximate expression for the atomic scattering factor, the correction factors for three crystalline peaks and an amorphous peak of Nylon 1212 were calculated and the formula of degree of crystallinity of Nylon 1212 was derived by a graphic multipeak resolution method. The degree of crystallinity calculated from the WAXD method is compatible with those obtained by density and calorimetry methods.     

Study on the denoising method for the electromagnetic ultrasonic echoes from multiple interfaces

The electromagnetic ultrasound is used in the detection of interfaces of the adhesive multilayer structures to solve the unstable coupling problem in ultrasonic testing by traditional piezoelectric transducers. Based on the analysis of the transforming mechanism of electromag-netic ultrasound energy and the resultant dead zone from mutual inductance of the transducer, the wavelet filtering by soft-thresholding and adaptive noise canceling methods are used simul-taneously to the detected electromagnetic ultrasonic signals to overcome the drawbacks of the low signal to noise ratio （SNR） and the wide intrinsic dead zone of the transducer. Processed results in the interface detection of a three layered adhesive sample of steel and rubber materials demonstrate that the wavelet filtering enhances the SNR about 12dB while the adaptive noise canceling narrows the dead zone effectively.