聚吡咯纳米阵列电极的光电化学

以多孔的铝阳极氧化膜(AAO)为模板制备了直径约为80 nm聚吡咯(PPy)纳米线的阵列电极, 并研究了它的光电化学响应. 结果表明, 在电极电位低于－0.1 V(vs Ag/AgCl)时出现的阴极光电流是由聚吡咯纳米线的p型半导体性质引起的, 其平带电位为－0.217 V. 聚吡咯纳米线的长度对光电流的影响较大, 最佳长度为42 nm. 这是因为在很短的聚吡咯纳米线阵列中PPy太少, 产生的光电流弱, 而在过长的聚吡咯纳米线阵列中光生电子在到达电极基底前易于与光生空穴复合而消失. 聚吡咯纳米线有可能作为纳米光电器件用于未来微器件系统.     

纳米丝负载钯催化剂的制备及催化烯烃加氢性能研究

利用电纺丝技术制备出苯乙烯-丙烯腈共聚物负载钯的纳米丝催化剂.对催化剂进行了SEM、TEM、IR和XPS的测试.所制备的催化剂对α-己烯催化氢化结果表明,该催化剂在常温、氢气常压下具有很高的催化活性和较好的重复使用性,并且催化氢化过程中存在烯烃的异构化反应.实验结果表明,反应时间为150min时纳米催化剂A对α-己烯催化加氢生成正己烷的转化率是传统催化剂PdCl2/-γAl2O3的4.7倍.     

Surface free energy and its effect on the elastic behavior of nano-sized particles, wires and films

Atoms at a free surface experience a different local environment than do atoms in the bulk of a material. As a result, the energy associated with these atoms will, in general, be different from that of the atoms in the bulk. The excess energy associated with surface atoms is called surface free energy. In traditional continuum mechanics, such surface free energy is typically neglected because it is associated with only a few layers of atoms near the surface and the ratio of the volume occupied by the surface atoms and the total volume of material of interest is extremely small. However, for nano-size particles, wires and films, the surface to volume ratio becomes significant, and so does the effect of surface free energy. In this paper, a framework is developed to incorporate the surface free energy into the continuum theory of mechanics. Based on this approach, it is demonstrated that the overall elastic behavior of structural elements (such as particles, wires, films) is size-dependent. Although such size-dependency is negligible for conventional structural elements, it becomes significant when at least one of the dimensions of the element shrinks to nanometers. Numerical examples are given in the paper to illustrate quantitatively the effects of surface free energy on the elastic properties of nano-size particles, wires and films.     

静电纺丝技术制备聚合物基中空结构材料

静电纺丝是一种制备纳米尺度连续长丝的技术, 采用静电纺丝技术高效可控地构筑微纳米中空结构材料备受关注. 本文综述了通过静电纺丝技术制备聚合物中空纤维和中空微球的研究进展, 展望了其在不同功能材料领域的发展前景.     

天然氨基酸水溶液中聚吡咯的电化学合成及其表征

报道了各种天然α-氨基酸水溶液中电化学聚合吡咯获得氨基酸掺杂的聚吡咯.实验表明吡咯在酸性氨基酸电解质中的氧化聚合电位较低,速度较快;而在碱性氨基酸水溶液中几乎无法进行电化学聚合.在电化学聚合过程中,氨基酸既作为支持电解质,又作为对离子被掺杂到聚合物中.该聚吡咯的电导率被测定为0.3～1.0 S/cm,在酸性氨基酸溶液中得到的聚合物电导率明显高于酸性较弱的氨基酸溶液中得到的聚合物,同时聚合物还具有良好的电化学活性和电化学稳定性,在-0.5 V到+0.5 V区间有一对氧化还原峰,该氧化还原峰的形状和特性在100次循环后基本保持不变.通过扫描电镜和透射电镜照片可以看出,不同种氨基酸的掺杂对聚吡咯的形貌具有影响,由于氨基酸的软模板效应,在数种氨基酸水溶液中能制得具有纳米纤维结构的聚吡咯.