SYNTHESIS OF MPt/C (M=La, Nd) CATALYSTS BY MICROWAVE RADIATION

1. INTRODUCTION The polymer electrolyte membrane fuel cells (PEMFC) are viewed as one of the most environmentally friendly propulsion system for automotive vehicle in the future, because of its distinct advantages such as high power density, lightweight, low environmental loads and low-temperature operation [1~3]. The biggest challenge for the development of fuel cells for automotive application is reduction of the cost of the cell stack (currently at $500 per kW, while 2004 PNGV goal…     

Ca,Sr共掺杂铈氧化物及其在甲烷氧化偶联反应中的应用

采用柠檬酸法制备了Ca,Sr共掺杂的CeO_2催化剂,发现共掺杂催化剂较单掺杂或未掺杂催化剂呈现出更好的催化甲烷氧化偶联(OCM)反应性能.通过表征可知,Ca,Sr共掺杂催化剂的物相为CeO_2和SrCO_3,Ca高度分散或掺杂于CeO_2之中;CeO_2的粒径明显变小;表面呈中等程度碱性;Ce基催化剂上的亲电氧物种数量随着碱土金属的掺杂而增大,亲电氧物种与晶格氧摩尔比(O_2-2+O-2)/O-2的大小顺序(CeSrCaCe SrCeO_2)与C2选择性一致;且SrCO_3相的存在有助于Ce基氧化物催化甲烷氧化偶联反应(OCM)性能的改善.     

尖晶石型(Zn1-xCdx)2SnO4粉体的制备与光催化性能

运用化学共沉淀法,制备了尖晶石型(Zn1-xCdx)2SnO4(x=0.04,0.05,0.06,0.07,0.08)纳米粉体.通过X射线衍射分析(XRD)、光电子能谱分析(XPS)、扫描电镜(SEM)、比表面积分析(BET)及光度法等手段研究了粉体结构及不同掺杂量对光催化活性的影响,确定了最佳掺杂量和热处理温度.以波长λ=312nm的光源对甲基橙水溶液进行光催化降解实验,讨论了光催化剂用量、甲基橙浓度、催化剂烧结时间、试液的pH值、光照时间等与甲基橙脱色率的关系.结果表明,该复合氧化物粉体平均粒径小于30nm,属立方晶系.在实验条件下,Cd2 的加入使Zn2SnO4的光催化活性明显提高,甲基橙的脱色率可达到98%.     

溴掺杂低密度PMP泡沫的制备技术研究

 详细论述了掺溴聚-4-甲基-1-戊烯(PMP)低密度泡沫的制备方法与性质测量。以PMP为泡沫骨架材料,均四甲苯/萘为溶剂,六溴苯为掺杂单体,利用热诱导倒相法制备出密度20～60 mg/cm³的掺溴低密度泡沫。在理论密度为50 mg/cm³时掺杂溴原子最大质量分数可达58.91%。利用扫描电镜观测泡沫结构表明：聚合物泡沫均是一种“叶片”状开放的结构,“叶片”的大小依赖于聚合物掺杂量的多少。随着掺杂量的增大,可供形核-长大的晶核也逐渐增多,最终得到的聚合物“叶片”较小。整个体系中密度分布是较为均匀的,掺杂单体在整个聚合物体系中基本不存在沉降的趋势。整个泡沫体系在低温区未出现较大的失重,溶剂的脱出较为完全线。     

锂电池阴极材料尖晶石型LiMn2－xLaxO4的研究

采用高温固相法,合成了掺杂改性的锂离子电池阴极材料尖晶石结构的LiMn2－xLaxO4（x=0、0.01、0.02、0.03、0.04、0.05、0.10）.用XRD对材料的晶体结构进行了表征.从材料的晶体结构、充放电测试和循环性能等方面分析了掺杂元素镧在稳定晶体结构中的作用.实验表明，掺杂后的材料在常温和高温下的循环性能均得到了明显改善.而且当掺杂量x≤0.04时，材料有较高的放电比容量.     

C60掺杂型导电高分子的研究

本文综述了近年来Ｃ６０掺杂型导电高分子的研究进展。通过实例，结合光谱的研究，阐述了Ｃ６０与被掺杂的导电高分子之间存在３种相互作用方式，在光电导材料和光折射材料等领域，Ｃ６０掺杂型高分子有很好的应用前景。     

SYNTHESIS OF MPt／C （M=La, Nd） CATALYSTS BY MICROWAVE RADIATION

In this paper. MPtC (M= La, Nd) catalysts of PEMFC were synthesized by microwaver adiation process. The crystallinity, and structure of catalysts were respectively analyzed by XRD and nitrogen adsorption tests. The activiy, of catalysts was investigated by electrochemistry experiment.The results showed that. compared with Pt/C catalyst prepared by typical impregnation-reduction process, the size of MPt C catalyst particle decreased and the available crystal for O2 reductionincreased. 2) the MPt, C catalysts had relatively high BET surface areas; and 3)these crystal transformations of the MPt/C catalyst brought high the electrocatalytic activity, and as a result,improved the power of PEMFC.     

Fabrication and characterization of cerium-doped barium titanate inverse opal by sol-gel method

Cerium-doped barium titanate inverted opal was synthesized from barium acetate contained cerous acetate and tetrabutyl titanate in the interstitial spaces of a polystyrene (PS) opal. This procedure involves infiltration of precursors into the interstices of the PS opal template followed by hydrolytic polycondensation of the precursors to amorphous barium titanate and removal of the PS opal by calcination. The morphologies of opal and inverse opal were characterized by scanning electron microscope (SEM). The pores were characterized by mercury intrusion porosimetry (MIP). X-ray photoelectron spectroscopy (XPS) investigation showed the doping structure of cerium, barium and titanium. And powder X-ray diffraction allows one to observe the influence of doping degree on the grain size. The lattice parameters, crystal size and lattice strain were calculated by the Rietveld refinement method. The synthesis of cerium-doped barium titanate inverted opals provides an opportunity to electrically and optically engineer the photonic band structure and the possibility of developing tunable three-dimensional photonic crystal devices.     

某些导电高分子的波谱性能

本文以聚吡咯和聚噻吩为例，对导电高分子的紫外－可见光谱、红外光谱、远红外及微波区的波谱性能进行了综述，并分析了波谱性能与结构的关系。对导电高分子波谱性能的实际应用前景也进行了论述。     

不同方法掺杂Au对纳米α-Fe2O3气敏性能的影响

分别采用共沉淀法、浸渍法、紫外辐照法制备了掺杂不同Au含量的α-Fe₂O₃纳米粉体, 并制作了旁热式厚膜型气敏元件. 用XRD、TG-DTA和TEM技术对纳米晶的晶型、晶粒大小及形貌进行了表征. 考察了掺杂方法、Au含量及焙烧温度对α-Fe₂O₃气敏性能的影响. 结果表明, 采用三种方法掺杂适量Au后, 都使α-Fe₂O₃的气敏性有了显著提高, 其中采用共沉淀法, 在400 ℃焙烧的Au质量分数为1.5％的α-Fe₂O₃的气敏性最佳.