Effect of Surface Acoustic Waves on Catalytic Activity of Reduced and Oxidized Nickel Thin Films Deposited on a LiTaO3 Substrate
Effect of Surface Acoustic Waves on Catalytic Activity of Reduced and Oxidized Nickel Thin Films Deposited on a LiTaO3 Substrate
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表面声波对 LiTaO3 基底上还原和氧化镍薄膜催化活性的影响
DOI：
10.1021/j100024a036
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发表时间：
1995
期刊：
影响因子：
--
通讯作者：
T. Noguchi
中科院分区：
文献类型：
--
作者：
Y. Inoue;Yukihisa S. Watanabe;T. Noguchi
研究了水平剪切声表面波(SAW)对乙醇在沿声表面波传播路径的还原和氧化镍催化剂上氧化的影响。当使用SAW时，氧化镍表面的催化活性提高了6倍，是还原镍表面的3.5倍。对于氧化后的镍表面，SAW引起了活性与氧分压的关系的反常变化，Po‘·活性随着Po的增加而增加，在4kPa时达到最大值，然后下降。在Po高于4kPa的范围内，对Po的反应级数在0.5到-0.5的范围内呈锯齿状变化，而在Po低于4kPa的范围内反应级数保持不变。反应级数的变化可以用氧的强吸附和乙醇的弱吸附来解释。对于还原的Ni表面，锯齿状反应对Po的反应级数没有明显的变化。X射线光电子能谱(XPS)和表面波传播损失(SAW)分析表明，氧化后的镍催化剂具有不同于还原镍催化剂的金属表面的双重结构。从可能的机理上讨论了表面声表面波对催化反应的影响，并提出表面声表面波的显著效应与氧化物表面的半导体性质有关，表面具有电场和声电效应，并可能与表面声表面波相互作用而产生独特的振动模式。
The effect of a surface acoustic wave (SAW) of a shear-horizontal type upon ethanol oxidation over reduced and oxidized Ni catalysts deposited on the propagation path of the SAW was studied. When the SAW was applied, the catalytic activity of the oxidized Ni surface increased by a factor of 6, which was 3.5-fold larger than that for the reduced Ni surface. For the oxidized Ni surface, the SAW caused an anomalous change in the dependence of the activity on the partial pressure of oxygen, Po'· the activity increased with increasing Po, attained a maximum at 4 kPa, and then decreased. For the reactionin the range of Po higher than4 kPa, the reaction order with respect to Po varied from 0.5 with SAW-off to—0.5 with SAW-on, whereas the order remained unchanged in the range of Po lower than 4 kPa. The change in the reaction order with SAW-on is explained in terms of the strongeradsorption of oxygen and weaker adsorption of ethanol. For the reduced Ni surface, no significant change in the reaction order with respect to Po occurred with SAW-on. XPS and the loss of SAW propagation showed that the oxidized Ni catalyst comprised the dual structure of a NiO layer-covered Ni metal, different from a metallic surface of the reduced Ni catalyst. The SAW effect on the catalytic reaction is discussed in terms of possible mechanisms, and it is proposed that the marked SAW effect on the NiO-covered Ni catalyst is related to semiconducting properties of the oxide surface, which has an electric field and acoustoelectriceffect and possibly a unique vibrational mode caused by interactions with the SAW.