ELECTROCATALYTIC ACTIVITY OF METALS IN ELECTRO-CHEMICAL REACTION

电化学反应中金属的电催化活性

• 批准号: 09450313
• 负责人: HORI Yoshio
• 金额: $ 7.3万
• 依托单位: Chiba University
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Scientific Research (B)
• 财政年份: 1997
• 资助国家: 日本
• 起止时间: 1997 至 1999
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-09450313/
• 关键词: COィイD22ィエD2; Electrochemical reduction; Metal; Electrode; Single crystal; Crystal orientation; Atomic configuration; Copper; 二酸化炭素; エチレン; エタノール; 白金; アセトニトリル; 電極触媒; ニ酸化炭素; 電極触媒活性

COィイD22ィエD2 is electrochemically reduced to various products, depending on the electrode metals. Pt can reduce COィイD22ィエD2 to CO strongly adsorbed on the electrode by hydrogen atoms preadsorbed on the electrode. We studied this reaction using high index platinum single crystal electrodes. The activity of the electrodes for the electrochemical reduction of COィイD22ィエD2 depends highly on atomic configuration of the electrode. The activity order is (111) < (997) < (332) < (221) < (110) < (331) < (110). This order agrees with the step atom density of the electrode surface. We presumed that the hydrogen atoms active for the reaction are the adsorbed hydrogen atoms at the 4-fold sites of the stepped atoms.The electrochemical reduction of COィイD22ィエD2 was also conducted with platinum electrodes in the electrolyte solution of acetonitrile-water mixtures. The main products are oxalic acid in water free acetonitrile, and formic acid in the electrolyte which contains some concentrations of water. They were obtained continuously from the platinum electrode in spite of the presence of strongly adsorbed CO on the surface. The product selectivity resembles that of Pb and Hg. The machanism was ratinalized in terms of prevention of the adsorption of the COィイD22ィエD2 anion radical on the electrode surface owing to the strongly adsorbed CO.High index plane single crystals of copper were also studied for the electrochemical reduction of COィイD22ィエD2. The product selectivity is remarkably affected by the crystal orientation of the electrode. (111) surface is favorable for methane formation, and (100) yields more ethylene. We employed some electrodes composed mainly of (100) and small fraction of (111) steps. (711) orientation, composed of 4 atomic rows of (100) surface and (111) step gave high ethylene selectivity. The ethylene formation may be activated by the presence of (111) step in (100) atomic configuration.

根据电极金属的不同，COイD22 D2被电化学还原为各种产物。Pt可通过预吸附在电极上的氢原子将CO还原为强吸附在电极上的CO。我们使用高折射率铂单晶电极研究了该反应。电极对CO_（22）O_活性顺序为（111）<（997）<（332）<（221）<（110）<（331）<（110）。该顺序与电极表面台阶原子密度一致。在乙腈-水混合电解质溶液中，在铂电极上进行了CO的电化学还原反应.主要产物为草酸在无水乙腈中的溶液和甲酸在含有一定浓度水的电解液中的溶液。它们是连续地从铂电极上获得的，尽管表面上存在强烈吸附的CO。产物选择性类似于Pb和Hg。该机理是合理的，在阻止吸附在电极表面上的CO阴离子自由基的吸附，由于强烈吸附的CO。高指数平面单晶铜还研究了电化学还原CO阴离子自由基D22的D22。电极晶向对产物选择性有显著影响。(111)表面有利于甲烷的生成，而（100）表面产生更多的乙烯。我们采用了一些主要由（100）和小部分（111）台阶组成的电极。(711)由（100）面和（111）台阶的4个原子列组成的取向提供了高的乙烯选择性。乙烯形成可以通过（100）原子构型中的（111）步骤的存在而活化。

项目成果

O.Koga: "Infrared Spectroscopic Observation of Intermediate Species on Ni and Fe Electrodes in the Electrochemical Reduction of CO_2 and CO to Hydrocarbons." Bull.Chem.Soc.Jpn.71. 315-320 (1998)

O.Koga：“CO_2 和 CO 电化学还原为碳氢化合物过程中 Ni 和 Fe 电极上中间物种的红外光谱观察”。

N.Hoshi: "Structural effect on the Rate of CO_2 Reduction on Single Crystal Electrodes of Palladium." J.Electroanal.Chem.,. 421. 15-18 (1997)

N.Hoshi：“结构对钯单晶电极 CO_2 还原率的影响。”

O.Koga: "Charge Displacement Adsorption of Carbon Monoxide on[110]Zone Copper Single Crystal Electrodes in Relation with PZC." Electrochim.Acta.,in press. (1998)

O.Koga：“与 PZC 相关的[110]区铜单晶电极上一氧化碳的电荷置换吸附。”

N. Hoshi, T. Suzuki, and Y. Hori: "Catalytic activity of COィイD22ィエD2 reduction rate on Pt single crystal electrodes Pt(S)-[n(111)x(111)], Pt(S)-[n(111)x(100)] and Pt(S)-[n(100)x(111)]."J. Phys. Chem. B. 101(42). 8520-8524 (1997)

N. Hoshi、T. Suzuki 和 Y. Hori：“Pt 单晶电极 Pt(S)-[n(111)x(111)]、Pt(S )-[n(111) 上 CO2D22 还原速率的催化活性)x(100)] 和 Pt(S)-[n(100)x(111)]。“J. Phys. Chem. B. 101(42). 8520-8524 (1997)

Nagahiro Hoshi, Kyoko Kagaya and Yoshio Hori: "Voltammograms of the single crystal electrodes of palladium in aqueous sulfuric acid electrolyte : Pd(S)-[n(111)×(111)] and Pd(S)-[n(100)×(111)]"J. Electroanal. Chem.. (in press).

Nagahiro Hoshi、Kyoko Kagaya 和 Yoshio Hori：“硫酸水溶液中钯单晶电极的伏安图：​​Pd(S)-[n(111)×(111)] 和 Pd(S)-[n(100) ×(111)]“J. Electroanal. Chem..（印刷中）。