Composite electrochemical catalysis utilizing mixed potential at the heterogeneous contact

利用非均相接触混合电势的复合电化学催化

• 批准号: 10650729
• 负责人: YAMAGUCHI Shu
• 金额: $ 2.5万
• 依托单位: Nagoya Institute of Technology
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Scientific Research (C)
• 财政年份: 1998
• 资助国家: 日本
• 起止时间: 1998 至 1999
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-10650729/
• 关键词: Mixed potential; Ionic conductor; Mixed conductor; Catalysis; Composite; NOx; DC Polarization; Space Charge; 触媒活性; 電荷移動反応; 交換電流密度; CO; 電子構造; 光電子分光; NO; NO_2; 電気化学; 表面吸着; Mixed potential; Ionic conductor; Mixed conductor; Catalysis; Composite; NOx; DC Polarization; Space Charge; 触媒活性; 電荷移動反応; 交換電流密度; CO; 電子構造; 光電子分光; NO; NO_2; 電気化学; 表面吸着

The present research project was aimed to develop a novel composite electrochemical catalysis which can utilize anomalous reactivity of gas species at the heterogeneous interface among porous oxide electrode with ion-electron mixed conductivity, solid electrolyte, and metallic electrode. In a microscopic scale, the catalysis is regarded as the mixture of microscaled cells with asymmetric electrode configuration that utilize so-called mixed potential, which is closely related to the space charge effect at the heterogeneous interface. In the early stage of the project, the mixture of Nd_<2-X>Ce_XCuO_4, Nd-doped CeO_2, and Au powder were examined for the catalytic activity to the NO/NO_2 Red-Ox reaction. The composite catalysis showed enhanced activity for the reaction compared to those of single component ones. It is also shown that the composite of NiO, YSZ, Au powder also showed the enhanced catalytic reaction for NOx Red-Ox. In order to examine the mechantism of the enhanced catalytic … More reaction of composites, electrochemical cells with three electrodes were examined. We found that the rate determinant steps are the mixed process of the competent absorption of NO_2 and O_2 on porous oxide and electron transfer reaction, and the simple electron transfer reaction on the Au electrode. The exchange current density of both reactions are deduced from the model. It should be noted that the relaxation of space charge, built-up at the interface of heterogeneous contact interface by both mobile ion and the adsorbed gas species is the essential mechanism for the selective enhancement of the catalytic reaction. Therefore the electronic band structure and electronic transport properties of oxides are estimated as playing important role in the formation of the mixed potential, that is one of the key to understand the anomalous reactivity of composite electrochemical catalysis. Based on these view points, the survey of possible candidates for the oxide electrode is conducted in accordance with the detailed investigation of electronic and ionic transport properties and electronic band structure by means of the photoelectron spectroscopy. As the direct reduction of NOx is difficult because of the very high activation energy, it is proposed the utilization of the proton or dissolved water in oxide electrode for the indirect reduction reaction. The detailed discussion on the oxide protonic conductors are also conducted. Less

本研究项目的目的是开发一种新型的复合电化学催化剂，该催化剂可以利用气体物种在多孔氧化物电极中具有离子电子混合电导率，固体电解质和金属电极的异质界面上的异常反应性。在微观尺度上，催化剂被认为是显微细胞与不对称电极构型的混合物，利用了所谓的混合电势，这与异质界面处的空间电荷效应密切相关。在项目的早期阶段，检查了ND_ <2-X> CE_XCUO_4，ND掺杂CEO_2和AU粉的混合物的催化活性，以对NO/NO_2 RED_2 RED-OX反应进行催化活性。与单个成分相比，复合催化显示了反应的活性增强。还表明，NIO，YSZ，AU粉的复合材料还显示了NOX红色氧化物的催化反应增强。为了检查增强催化性的机制……组成的更多反应，检查了用三个电极的电化学细胞。我们发现确定的步骤是在多孔氧化物和电子传递反应上对NO_2和O_2进行有效滥用的混合过程，以及在AU电极上的简单电子传输反应。两种反应的交换电流密度都是从模型中推导的。应当指出的是，流动离子和吸附气体种类在异质接触界面的界面上构建的空间电荷的松弛是选择性增强催化反应的基本机制。因此，氧化物的电子带结构和电子传输特性估计是在混合电势的形成中起重要作用，这是理解复合电化学催化的异常反应性的关键之一。基于这些观点，对氧化物电极的可能候选物进行调查是根据通过光电光谱法的电子和离子传输性能和电子带结构的详细投资进行的。由于由于具有很高的活化能，因此很难直接降低NOX，因此提出了在氧化物电极中质子或溶解的水的利用来进行间接还原反应。还进行了有关氧化电极的详细讨论。较少的