高温热解法制备的纳米碳纤维的透射电子显微镜研究

以纳米尺度的镍粉为催化剂，使乙炔气体在高温下热解，制备了纳米碳纤维，利用透电子显微镜对样品的形貌和结构进行了观察研究，讨论了纳米碳纤维的形成机制。     

大功率CO_2激光器非平衡态合成WO_3/Al_2O_3新型陶瓷催化剂

用大功率 CO2 激光在高温、快速、非平衡态下合成 WO3/ Al2 O3烯烃歧化反应催化剂。利用 XRD、XPS、DTA TG等技术对催化剂的性质进行了研究。表明激光合成催化剂中存在非平衡态的 Alx WO3。低于六价的钨是烯烃歧化反应的活性中心 .同时还考查了催化剂组成、激光功率及熔炼时间与丙烯歧化反应活性之间的关系。     

激光诱导H_2S催化裂解制备H_2的研究

在室温常压静态条件下研究了以Ｖ２Ｏ５／ＴｉＯ２为催化剂，紫外脉冲激光诱导Ｈ２Ｓ催化分解为Ｈ２和Ｓ的反应及其机理。考察了产氢量与激光不同照射条件之间的关系。     

炸药件加成型硅橡胶包覆技术研究

针对加成型硅橡胶包覆炸药件催化剂中毒以及脱粘问题,对影响加成型硅橡胶硫化过程的因素及其粘接性开展研究。结果表明：防中毒剂异丙醇铝可较好解决炸药加成型硅橡胶包覆催化剂中毒的问题;催化剂种类及加料顺序对硫化速度有一定影响;适当的硅烷偶联剂以及适宜的表面处理方法可有效改善加成型硅橡胶对炸药的粘接性能。     

Thermal stabilities of nanoporous metallic electrodes at elevated temperatures

Currently Pt-based metals are the best catalytic electrodes for fuel cells at operating temperatures below 500 °C. Pure platinum electrodes suffer degradation of microstructure over time at elevated temperatures due to Ostwald ripening. In this paper, better thermal stability of Pt–Ni nanoporous thin films relative to pure Pt is reported. Based on ab initio calculations, it was found that both the surface energy of a Pt_0.7Ni_0.3 cluster and the energy change of the Pt–Ni alloy cluster upon ripening on yttria stabilized zirconia (YSZ) solid electrolyte were lower than pure Pt. This suggested a better thermal stability of Pt_0.7Ni_0.3 than Pt. In addition, annealing impacts on microstructures and properties of nanoporous Pt and Pt–Ni alloy thin films were examined experimentally. SEM images show dramatic porosity reduction for pure Pt after annealing at temperatures of 400–600 °C but insignificant microstructure change for Pt–Ni nanoporous thin films. As a result, in solid oxide fuel cells using nanoporous Pt–Ni cathodic catalysts instead of pure Pt, better stability, lower electrode impedances, and higher power densities were achieved at elevated operating temperatures (350–500 °C).     

High surface area synthesis,electrochemical activity,and stability of tungsten carbide supported Pt during oxygen reduction in proton exchange membrane fuel cells

The oxidation of carbon catalyst supports to carbon dioxide gas leads to degradation in catalyst performance over time in proton exchange membrane fuel cells (PEMFCs). The electrochemical stability of Pt supported on tungsten carbide has been evaluated on a carbon-based gas diffusion layer (GDL) at 80 °C and compared to that of HiSpec 4000™ Pt/Vulcan XC-72R in 0.5 M H₂SO₄. Due to other electrochemical processes occurring on the GDL, detailed studies were also performed on a gold mesh substrate. The oxygen reduction reaction (ORR) activity was measured both before and after accelerated oxidation cycles between +0.6 V and +1.8 V vs. RHE. Tafel plots show that the ORR activity remained high even after accelerated oxidation tests for Pt/tungsten carbide, while the ORR activity was extremely poor after accelerated oxidation tests for HiSpec 4000™. In order to make high surface area tungsten carbide, three synthesis routes were investigated. Magnetron sputtering of tungsten on carbon was found to be the most promising route, but needs further optimization.     

Nanostructured platinum catalyst layer prepared by pulsed electrodeposition for use in PEM fuel cells

Nanostructured thin catalyst layer with uniform distribution of platinum particles on a GDL useful for PEM fuel cell was obtained by preferential pulsed electrodeposition (PED) from a dilute solution of chloroplatinic acid. A low platinum loading on the electrode was obtained by PED method, without any loss in fuel cell performance compared with electrodes prepared by conventional brush coating method. The electrodeposition was optimized by varying the duty cycle and current density. The fuel cell performance was found to be 350 mA/cm² at an operating voltage of 0.6 V at 60 °C with hydrogen and air as reactants at ambient pressure. The nanostructured thin catalyst layer showed a very less ohmic resistance of 0.00076 mΩ/cm².     

封闭循环TEA CO2激光器用催化剂的实验研究

在不同的催化剂和不同温度的条件下,用磁氧分析仪监测了封离型TEA C0₂激光器中O₂含量随时间或脉冲次数的变化。对实验现象进行了分析。对几种催化剂的特性给出了详细的比较。     

The surface properties of aluminated meso–macroporous silica and its catalytic performance as hydrodesulfurization catalyst support

Aluminated mesoporous silica was prepared by multiple post-grafting of alumina onto uniform mesoporous SiO_2 ,which was assembled from monodisperse SiO_2 microspheres.Hydrodesulfurization(HDS)catalyst was prepared by loading Ni and Mo active components onto the aluminated uniform mesoporous SiO_2 ,and its HDS catalytic performance was evaluated using hydrodesulfurization of dibenzothiophene as the probe reaction at 300°C and 6.0 MPa in a tubular reactor.The samples were characterized by N_2 physisorption,scanning electronic microscopy,Fourier transform infrared spectrum,X-ray diffraction(XRD),temperature-programmed desorption of ammonia(NH_3-TPD),~(27)Al nuclear magnetic resonance(~(27)Al-NMR)and high-resolution transmission electron microscopy(HRTEM).The results showed that the Si–OH group content of SiO_2 was mainly dependent on the pretreatment conditions and had significant influence on the activity of the Ni Mo catalyst.The surface properties of the aluminated SiO_2 varied with the Al_2O_3-grafting cycles.Generally after four cycles of grafting,the aluminated SiO_2 behaved like amorphous alumina.In addition,plotting of activity of Ni Mo catalysts supported on aluminated meso–macroporous silica materials against the Al_2O_3-grafting cycle yields a volcano curve.     

Formation of a low reflective surface on crystalline silicon solar cells by chemical treatment using Ag electrodes as the catalyst

A new method was developed for making a porous silicon layer as an anti-reflective coating on the top of crystalline silicon solar cells. The porous silicon layer was formed in a mixed solution of H₂O₂ and HF by using screen-printed Ag front electrodes as the catalyst. With the help of the catalytic effect, porous silicon layers were formed by treatment in a solution chemically milder than conventional solutions. The multi-crystalline silicon solar cell covered with the porous silicon layer showed a surface reflectance below 15% in a wavelength region of 400–800 nm.