Decrypting the Controlled Product Selectivity over Ag−Cu Bimetallic Surface Alloys for Electrochemical CO2 Reduction

Electrochemical CO₂ reduction reaction (ECO₂RR) with controlled product selectivity is realized on Ag−Cu bimetallic surface alloys, with high selectivity towards C2 hydrocarbons/alcohols (≈60 % faradaic efficiency, FE), C1 hydrocarbons/alcohols (≈41 % FE) and CO (≈74 % FE) achieved by tuning surface compositions and applied potentials. In situ spectral investigations and theoretical calculations reveal that surface-composition-dependent d-band center could tune *CO binding strengths, regulating the *CO subsequent reaction pathways and then the product selectivity. Further adjusting the applied potentials will alter the energy of participated electrons, which leads to controlled ECO₂RR selectivity towards desired products. A predominant region map, with an indicator proposed to evaluate the thermodynamic predominance of the *CO subsequent reactions, is then provided as a reliable theoretical guidance for the controllable ECO₂RR product selectivity over bimetallic alloys.     

Visible-light-driven Oxygen Vacancy and Carbon Doping of C@TiO2-x Photocatalyst for Enhanced Pollutants Degradation Performance

Oxygen Vacancy (OVs) and carbon doping of the photocatalyst body will significantly enhance the photocatalytic efficiency. However, synchronous regulation of these two aspects is challenging. In this paper, a novel C@TiO_2-x photocatalyst was designed by coupling the surface defect and doping engineering of titania, which can effectively remove rhodamine B (RhB) and has a relatively high performance with wide pH range, high photocatalytic activity and good stability. Within 90 minutes, the photocatalytic degradation rate of RhB by C@TiO_2-x (94.1 % at 20 mg/L) is 28 times higher than that of pure TiO₂. Free radical trapping experiments and electron spin resonance techniques reveal that superoxide radicals (⋅O²⁻) and photogenerated holes (h⁺) play key roles in the photocatalytic degradation of RhB. This study demonstrates the possibility of regulating photocatalysts to degrade pollutants in wastewater based on an integrated strategy.     

AFM forces measured between gold surfaces coated with self-assembled monolayers of 1-hexadecanethiol

An atomic force microscope (AFM) was used to measure the forces between gold surfaces with and without hydrophobizing them by the self-assembly of 1-hexadecanethiol. The forces measured between bare gold surfaces were fitted to the Derjaguin-Landau-Verwey-Overbeek (DLVO) theory with a Hamaker constant of 1.2 x 10 (-20) J, which was close to the value determined using the methylene iodide contact angle method but was lower than that calculated using the Lifshitz theory. When the surfaces were hydrophobized in a 0.01 mM thiol-in-ethanol solution for 10 min, the measured forces exhibited a long-range force with a decay length of 35 nm. Despite its high water contact angle (105 degrees ), the force curve was smooth and exhibited no steps. When the surfaces were hydrophobized in a 1 mM thiol solution for longer than 6 h, however, the force curves exhibited steps, indicating that the long-range attractions were caused by bridging bubbles. When the measurements were conducted after washing the substrates with organic solvents, the steps disappeared and long-range attractive forces appeared. In the presence of ethanol, the water contact angle decreased to below 90 degrees , the attraction became weaker, and the force curves became smooth. On the basis of the results obtained in the present work, possible mechanisms for the long-range attractions are discussed.     

Surface-directed phase separation via a two-step quench process in binary polymer mixture films with asymmetry compositions

Surface-directed phase separation via a two-step quench process in asymmetry polymer mixtures is numerically investigated by coupling the Flory-Huggins-de Gennes equation with the Cahn-Hilliard-Cook equation. Two distinct situations, i.e., the minority component is preferred by the surface and the majority component is preferred by the surface, are discussed, respectively. The morphology and evolution dynamics of the phase structure, especially the secondary domain structure, are analyzed. The wetting layer formation mechanisms during the two-step quench process are examined. The simulated results demonstrate that different secondary domain structures in these two situations can be induced by the second quench with deeper quench depth, which can be used to tailor phase morphology. It is also found that, in the second quench process, the evolution of the wetting layer thickness can cross over to a faster growth when the preferential component is the minority component. In this situation, the formation mechanism of the wetting layer will change and is eventually determined by the second quench depth. However, when the preferential component is the majority component, a deeper second quench depth corresponds to a slower growth of the wetting layer thickness. The chemical potential is calculated to explain the difference regarding the growth dynamics of the wetting layer thickness between these both situations.     

High-yield bamboo-shaped carbon nanotubes from cresol for electrochemical application

High-yield bamboo-shaped carbon nanotubes (BCNTs) have been produced by using cresol as the precursor, for the first time and there are almost no straight CNTs or amorphous carbon found in the product: the role of cresol in promoting the growth of BCNTs is discussed; improved cycle stability and electric conductivity of the BCNTs as an anode additive in a lithium ion battery are achieved.     

维修中心参与回收时闭环供应链的定价决策及回收模式选择

维修中心参与回收是闭环供应链研究面临的新情境。本文将维修中心可以免费获得零部件的情形考虑进来, 分别给出了回收商单回收渠道模式、回收商与第三方维修中心双回收渠道模式, 在此基础上深入研究了两种模式下闭环供应链的定价决策及回收模式选择问题。结果表明:两种模式下, 官方维修中心免费获得零部件数量的增加都会对制造商利润产生积极影响, 但不会对其回购价产生影响; 双回收渠道模式下, 第三方维修中心免费获得零部件数量的增加会使制造商的回购价降低, 使其利润增加。从有偿回收产品总数量最大化的角度来看, 当第三方维修中心免费获得零部件的数量较低且两种渠道之间的竞争程度较高时, 应该选择双回收渠道模式。从制造商利润最大化的角度来看, 模式选取决策与两种模式下官方维修中心免费获得零部件数量的相对大小有关。     

A Galerkin boundary element method based on interpolatory Hermite trigonometric wavelets

A Galerkin boundary element method based on interpolatory Hermite trigonometric wavelets is presented for solving 2-D potential problems defined inside or outside of a circular boundary in this paper. In this approach, an equivalent variational form of the corresponding boundary integral equation for the potential problem is used; the trigonometric wavelets are employed as trial and test functions of the variational formulation. The analytical formulae of the matrix entries indicate that most of the matrix entries are naturally zero without any truncation technique and the system matrix is a block diagonal matrix. Each block consists of four circular submatrices. Hence the memory spaces and computational complexity of the system matrix are linear scale. This approach could be easily coupled into domain decomposition method based on variational formulation. Finally, the error estimates of the approximation solutions are given and some test examples are presented.     

Synthesis and Characterization of NASICON Nanoparticles by Sol-gel Method

Na superionic conductor(NASICON) nanoparticles were synthesized by a modified sol-gel method and sintered at a temperature range of 800―1000 ℃.The performance of the samples was characterized by the analysis methods of X-ray diffraction(XRD),Fourier transform infrared spectroscopy(FTIR),and transmission electron microscopy(TEM) as well as conductivity measurement.Compared with those sintered at other temperatures,the NASICON material sintered at 900 ℃ had the best crystalline structure and higher conductivi...     

A Galerkin boundary node method and its convergence analysis

The boundary node method (BNM) exploits the dimensionality of the boundary integral equation (BIE) and the meshless attribute of the moving least-square (MLS) approximations. However, since MLS shape functions lack the property of a delta function, it is difficult to exactly satisfy boundary conditions in BNM. Besides, the system matrices of BNM are non-symmetric.     

高阶变系数函数方程的振动性

建立了一类高阶非线性变系数函数方程一切解振动的几个充分条件,并且给出了在差分方程中的若干应用.结果全面推广了某些文献的结果.