孪晶HZSM-5@Silicalite-1核壳结构催化剂的制备及甲苯甲醇烷基化性能研究

本研究采用水热结晶法合成了孪晶HZSM-5分子筛，并在表面外延生长Silicalite-1（S-1）纯硅沸石，制备了HZSM-5@Silicalite-1核壳结构催化剂。与孪晶HZSM-5相比，HZSM-5@Silicalite-1核壳结构催化剂在甲苯甲醇烷基化反应中表现出优异的催化性能。在470℃、0.1 MPa和临氢反应条件下，HZSM-5@40Silicalite-1催化剂的甲苯单程转化率为8.5%，对二甲苯选择性为98.4%。进一步研究了核相HZSM-5与S-1壳层前驱体固液质量比对表面S-1晶体生长的影响，同时考察了S-1壳层对孪晶HZSM-5催化性能的影响。通过SEM、XRD、XRF、液体静态吸附、N₂吸附-脱附、NH₃-TPD、Py-FTIR等表征实验对核壳材料的结构和酸性质进行了详细研究。     

具时滞影响的一般BAM神经网络的有限时间反同步

本文研究一类具有时滞影响的一般BAM神经网络有限时间反同步问题.通过设计合适的状态控制器,引入新颖的数学分析方法,并利用不等式技巧,在不借助已有的有限时间稳定性定理,建立了驱动-响应框架下所研究模型的有限时间反同步的判据,所得到的结果推广并改进已有文献的结论.最后通过数值例子验证了所得理论结果的有效性.     

Importance of PbI_2 morphology in two-step deposition of CH_3NH_3PbI_3 for high-performance perovskite solar cells

Controlling the morphology of the perovskite film is an effective way to improve the photoelectric conversion efficiency of solar cell devices. In this work, we study the influence of the crystallization condition on PbI_2 morphology and the performances of resulting perovskite solar cells. The PbI_2 morphologies and coverage rates under different formation conditions such as solvent effect, slow crystallization at room temperature and substrate-preheating, are found to be of crucial importance for preparing high-quality perovskite. The generation of loosely packed disk-like PbI_2 film with interpenetrating nanopores promotes the penetration of methyl ammonium iodide(MAI), leading to a better crystallinity of the perovskite film, and a best repeatable power conversion efficiency of 11.59% is achieved when methyl ammonium lead triiodide(CH_3NH_3PbI_3, MAPbI_3) is employed. In addition, an excellent device is also obtained with an efficiency of more than 93% to remain after working for 43 days.