钛酸盐(钴、镓)沸石分子筛的合成与表征

钛酸钴;钛酸镓;水热合成;钛酸盐(钴、镓)沸石分子筛的合成与表征     

半绝缘磷化铟中与非化学配比有关的深能级缺陷

在不同的化学配比条件下制备了半绝缘磷化铟材料,其中包括配比和富铟熔体中的铁掺杂以及磷气氛和磷化铁气氛下高温退火非掺杂晶片.在这些半绝缘磷化铟材料中检测到了与非化学配比有关的深能级缺陷.通过对大量的原生掺铁和非掺退火半绝缘磷化铟材料中的缺陷的研究,发现原生深能级缺陷与材料的电学参数质量密切相关.迁移率低、热稳定性差的掺铁半绝缘磷化铟材料中有大量的能级位于0.1～0.4eV之间的缺陷.高温退火非掺磷化铟抑制了这些缺陷的产生,获得了迁移率高、均匀性好的高质量半绝缘材料.根据这些结果,我们提出了一种通过控制化学配比制备高质量半绝缘磷化铟材料的方法.     

磷化镍晶体结构的密度泛函理论研究

运用密度泛函理论系统地研究了已知的磷化镍晶体如Ni3P、 Ni12P5、 Ni2P、 Ni5P4、 NiP、 NiP2 和 NiP3等的结构、成键以及相关的热力学稳定性,对于结构简易化合物（Ni2P和NiP3）的弹性行为进行了预测。这些数据有助于更好的理解磷化镍的催化活性。     

Self‐Supported FeP‐CoMoP Hierarchical Nanostructures for Efficient Hydrogen Evolution

Fabricating highly efficient electrocatalysts for electrochemical hydrogen generation is a top priority to relief the global energy crisis and environmental contamination. Herein, a rational synthetic strategy is developed for constructing well‐defined FeP?CoMoP hierarchical nanostructures (HNSs). In general terms, the self‐supported Co nanorods (NRs) are grown on conductive carbon cloth and directly serve as a self‐sacrificing template. After solvothermal treatment, Co NRs are converted into well‐ordered Co?Mo nanotubes (NTs). Subsequently, the small‐sized Fe oxyhydroxide nanorods arrays are hydrothermally grown on the surface of Co?Mo NTs to form Fe?Co?Mo HNSs, which are then converted into FeP?CoMoP HNSs through a facile phosphorization treatment. FeP?CoMoP HNSs display high activity for hydrogen evolution reaction (HER) with an ultralow cathodic overpotential of 33 mV at 10 mA cm^?2 and a Tafel slope of 51 mV dec^?1. Moreover, FeP?CoMoP HNSs also possess an excellent electrochemical durability in alkaline media. First‐principles density functional theory (DFT) calculations demonstrate that the remarkable HER activitiy of FeP?CoMoP HNSs originates from the synergistic effect between FeP and CoMoP.     

A Phosphanyl-Phosphagallene that Functions as a Frustrated Lewis Pair

Phosphagallenes ( 1 a / 1 b ) featuring double bonds between phosphorus and gallium were synthesized by reaction of (phosphanyl)phosphaketenes with the gallium carbenoid Ga(Nacnac) (Nacnac=HC[C(Me)N(2,6-i-Pr₂C₆H₃)]₂). The stability of these species is dependent on the saturation of the phosphanyl moiety. 1 a , which bears an unsaturated phosphanyl ring, rearranges in solution to yield a spirocyclic compound ( 2 ) which contains a P=P bond. The saturated variant 1 b is stable even at elevated temperatures. 1 b behaves as a frustrated Lewis pair capable of activation of H₂ and forms a 1:1 adduct with CO₂.     

Electronic and structural properties of the InP(1 0 0)(2 × 4) surface studied by core-level photoemission and scanning tunneling microscopy

The (2 × 4)-reconstructed InP(1 0 0) surfaces have been investigated by scanning tunneling microscopy (STM) and synchrotron-radiation core-level photoelectron spectroscopy. STM observations show that the α2 model describes the atomic structure of the InP(1 0 0)(2 × 4) surface in a limited range of the surface-preparation conditions, as predicted theoretically but not previously observed. STM results also support the accuracy of the previously found mixed-dimer structure for the InP(1 0 0)(2 × 4) surface under less P-rich conditions. A study of P 2p core-level photoelectron spectra, measured with different surface-sensitivity conditions, demonstrates that P 2p photoemission from the mixed-dimer InP(1 0 0)(2 × 4) surface consists of at least two surface-core-level-shift (SCLS) components which have kinetic energies approximately 0.4 eV higher and 0.3 eV lower than the bulk emission. On the basis of the surface-sensitivity difference between these SCLSs, they are related to the third-layer and top-layer P sites in the mixed-dimer structure, respectively.     

Ab initio calculations and dynamical properties of the Se:InP(1 1 0) and Te:InP(1 1 0)

We present results of ab initio theoretical investigations of the structural and dynamical properties of the Se:InP(1 1 0) and Te:InP(1 1 0) surfaces, by employing the plane wave pseudopotential method, the local density approximation of the density functional theory, and a linear response scheme. For both adsorbates we have used the so-called exchange geometry (the chalcogen atoms replacing P in the top two atomic layers). A detailed discussion is provided of the relaxed surface geometry and phonon dispersion curves along two principal symmetry directions. It is found that the adsorption of Se (or Te) atoms on InP(1 1 0) leads to phonon modes in the acoustic-optical gap region for bulk InP. The characteristic atomic displacement patterns of selected phonon modes on these surfaces have been compared and contrasted with those on the clean InP(1 1 0) surface.     

The epitaxial growth of gallium arsenide using triethylarsine

The thermal decomposition of triethylarsine (TEAs) has been studied. It decomposes at a lower temperature than arsine (AsH₃). The decomposition proceeds via a radical process at a temperature above 700°C. Epitaxial growth using TEAs has been investigated. A gallium arsenide (GaAs) layer with good morphology was obtained, but the layer was found to contain a considerable amount of carbon impurity originating from TEAs. The use of TEAs with 10% AsH₃ or with 20% ammonia (NH₃) apparently improves the quality of GaAs layer. A possible scheme for reducing carbon incorporation is discussed.