Effects of Resonance Oscillation on Activation of Thin film Catalysts Deposited on a Ferroelectric Substrate

共振振荡对铁电基板上沉积薄膜催化剂活化的影响

基本信息

批准号：
07454185
负责人：
INOUE Yasunobu
金额：
$ 4.48万
依托单位：
Nagaoka University of Technology
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (B)
财政年份：
1995
资助国家：
日本
起止时间：
1995 至 1996
项目状态：
已结题

项目摘要

In an attempt to design a heterogeneous catalyst with artificially controllable functions, resonance oscillation phenomena generated on a ferroelectric crystal by applying radio frequency electric power were applied. A poled ferroelectric single crystal of lithium niobate (LiNbO_3) was used as a substrate, on which either Pd film or Al was deposited. These metal films were used not only as a catalyst but as an electrode to introduce rf power. In the catalytic ethanol oxidation on a 40 nm thick Pd film deposited on LiNbO_3, resonance oscillation at a frequency of 3.4 MHz at a power of 3 W caused an immediate increase in acetaldehyde production by a factor of 1900, and the high activity was maintained until the power was turned off. The application of non-resonance frequency caused no significant activity enhancement. The activation energy of the reaction was 156 kJ mol^<-1> with power-off, whereas it decreased dramatically to 12 kJ mol^<-1> with power-on. For a sample using a catalytically inactive Al thin film, little increase in catalytic activity was observed. Surface potential measurements showed that the resonance frequency affected the distribution of electrons at surfaces, whereas no change occurred when non-resonance frequency was applied to the catalyst. A laser Doppler method was employed to measure lattice displacement. On the basis of these results, the effects of resonance oscillation which lead to the anomalous enhancement of catalytic activity are considered to be associated with the lattice displacement of catalyst surface and changes in the surface potential.

为了尝试设计具有人工控制功能的异质催化剂，应用了通过应用射频电力功率在铁电晶体上产生的共振振荡现象。将氯酸锂（Linbo_3）的螺旋铁电晶体用作底物，在其上沉积了PD膜或Al。这些金属膜不仅被用作催化剂，而且用作引入RF功率的电极。在沉积在linbo_3上的40 nm厚的PD膜上的催化乙醇氧化中，共振的频率为3.4 MHz的频率为3.4 M，导致3 W的频率使乙醛产生立即增加1900倍，并保持高活性直到保持高活性直至保持高活性电源关闭了。非共振频率的应用没有引起显着的活性增强。反应的激活能为156 kj mol^<-1>，而动力可以熄灭，而用电力进行急剧下降至12 kj mol^<-1>。对于使用催化无效的Al薄膜的样品，几乎没有观察到催化活性的增加。表面电势测量表明，共振频率影响了表面上电子的分布，而当将非谐振频率应用于催化剂时，没有发生变化。采用激光多普勒方法来测量晶格位移。基于这些结果，共振振荡的影响导致催化活性的异常增强被认为与催化剂表面的晶格位移和表面电位变化有关。