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1.
First-principles study of the co-effect of carbon doping and oxygen vacancies in ZnO photocatalyst 下载免费PDF全文
Although tuning band structure of optoelectronic semiconductor-based materials by means of doping single defect is an important approach for potential photocatalysis application,C-doping or oxygen vacancy(Vo)as a single defect in ZnO still has limitations for photocatalytic activity.Meanwhile,the influence of co-existence of various defects in ZnO still lacks sufficient studies.Therefore,we investigate the photocatalytic properties of ZnOx C0.0625(x=0.9375,0.875,0.8125),confirming that the co-effect of various defects has a greater enhancement for photocatalytic activity driven by visible-light than the single defect in ZnO.To clarify the underlying mechanism of co-existence of various defects in ZnO,we perform systematically the electronic properties calculations using density functional theory.It is found that the coeffect of C-doping and Vo in ZnO can achieve a more controllable band gap than doping solely in ZnO.Moreover,the impact of the effective masses of ZnOxC0.0625(x=0.9375,0.875,0.8125)is also taken into account.In comparison with heavy Vo concentrations,the light Vo concentration(x=0.875)as the optimal component together with C-doping in ZnO,can significantly improve the visible-light absorption and benefit photocatalytic activity. 相似文献
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表面活性剂对3-甲基吡啶电氧化制取烟酸的影响 总被引:1,自引:0,他引:1
研究了在阳极液中加入不同类型和不同浓度表面活性剂对3-甲基吡啶电氧化的影响. 结果表明, 十六烷基三甲基溴化铵、脂肪醇聚氧乙烯醚硫酸钠、十二烷基苯磺酸钠、十二烷基二甲基甜菜碱和山梨醇酐单硬脂酸酯的胶团对3-甲基吡啶电氧化有明显的促进作用. 实验结果还表明, 在低浓度的硫酸为支持电解质阳极液中加入表面活性剂与不加表面活性剂相比, 3-甲基吡啶电氧化制取烟酸的选择性和电流效率明显提高. 相似文献
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Several kinds of models have already been proposed to explain the photoemission process. The exact photoemission theory of the semiconductor photocathode was not well established after decades of research. In this paper an integral equation of quantum efficiency (QE) is constructed to describe the photoemission of positive electron affinity (PEA) of the semiconductor photocathode based on the three-step photoemission model. Various factors (e.g., forbidden band gap, electron affinity, photon energy, incident angle, degree of polarization, refractive index, extinction coefficient, initial and final electron energy, relaxation time, external electric field and so on) have an impact on the QE of the PEA semiconductor photocathode, which are entirely expressed in the QE equation. In addition, a simulation code is also programmed to calculate the QE of the K2CsSb photocathode theoretically at 532 nm wavelength. By and large, the result is in line with the expected experimental value. The reasons leading to the distinction between the experimental and theoretical QE are discussed. 相似文献
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用so1-gel法以正硅酸乙酯、乙醇和蒸馏水为原料,以盐酸为催化剂,包埋三联吡啶钌[Ru(bpy)3C12]制备催化Belousov-Zhabotinsky(BZ)反应的非线性光催化薄膜,并利用紫外分光光度法测定了在薄膜中Ru(bpy)3Cl2的包埋量.通过投影图像的方法光激发BZ反应,在包埋Ru(bpy)3C12的薄膜上产生化学波图像.在薄膜中演化形成的图像具有相当高的图像清晰度.在图像的演化过程中,具有图像反转、边界增强、图像分割等图像处理能力,并可以通过改变BZ反应条件来调控增强某些图像处理能力. 相似文献
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基于铁基超导体的多带能隙特征,采用两带模型,假设带内电子配对为各项同性,带间电子配对序参量为coskxcosky形式.利用Gro′kov理论,推导了层状铁基超导体的二维Ginzburg-Landau方程,并给出了自由能密度和垂直于二维载流子运动平面的上临界场表达式.计算表明,上临界场在转变温度附近随温度变化的曲线呈对数形,该特征与最近的一些实验结果相符合,并且与三维体系的上临界场有显著不同,这一特点是由系统的准二维特征所决定. 相似文献
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Effect of size polydispersity on the structural and vibrational characteristics of two-dimensional granular assemblies 下载免费PDF全文
Two-dimensional disordered granular assemblies composed of 2048 polydispersed frictionless disks are simulated using the discrete element method. The height of the first peak of the pair correlation function, g1, the local and global gbond orientational parameters lψ6and ψ6, and the fluctuations of these parameters decrease with increasing polydispersity s,implying the transition from a polycrystalline state to an amorphous state in the system. As s increases, the peak position of the boson peak ωBP shifts towards a lower frequency and the intensity of the boson peak D(ωBP)/ωBP increases, indicating that the position and the strength of the boson peak are controlled by the polydispersity of the system. Moreover, the inverse of the boson peak intensity ωBP/D(ωBP), the shear modulus G, and the basin curvature SIS all have a similar dependence on s, implying that the s dependence of the vibrational density of states at low frequencies likely originates from the s dependence of the basin curvature. 相似文献