In Situ Scanning Tunneling Microscope Study of the Passivation of Cu(111)
In Situ Scanning Tunneling Microscope Study of the Passivation of Cu(111)
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Cu(111)钝化的原位扫描隧道显微镜研究
DOI：
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发表时间：
1999
期刊：
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通讯作者：
P. Marcus
中科院分区：
文献类型：
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作者：
V. Maurice;H. Strehblow;P. Marcus
用原位扫描隧道显微镜研究了Cu（111）表面在0.1M硼酸盐缓冲溶液（pH9.3）中钝化膜的成核、生长机制和结构。在将暴露于空气的电抛光表面的动电位降低至1.12 V/标准氢电极（SHE）之后，获得了以具有单原子台阶的台阶为特征的表面形貌。在0.03 V/SHE的单一Cu{sub 2}O钝化层的形成首先通过分配给局部阻塞的步骤流程的步骤的粗糙化进行，由于在步骤处的氧化物的溶解和优先成核之间的竞争。观察到的氧化物核宽2- 3 nm，约一个原子平面高。该过程导致氧化膜的颗粒状结构完全覆盖梯田。最初的阶地地形完全改变了。增厚的氧化层导致不稳定的扫描隧道显微镜成像，尽管存在的氧化物的带隙中的子带。在0.98 V/SHE下制备的Cu{sub 2}O{vert_bar}CuO-Cu（OH）{sub 2}双钝化膜的特征在于没有可检测到的结晶性证据的颗粒状结构。颗粒的横向尺寸范围为1至5纳米。测得的高度差为{le}1.5 nm。通过在钝化膜的导带中的电子隧穿发生稳定的成像。金属表面形貌可以通过将氧化物膜的动电位还原至0.92 V/SHE来恢复。在这些氧化/还原处理中，通过逐步聚结消除了最小的阶地，这导致了更陡峭的表面轮廓。«少
In situ scanning tunneling microscopy has been used to study the nucleation and growth mechanisms and the structure of passive films formed on Cu(111) surfaces in 0.1 M borate buffer solution (pH 9.3). A surface topography characterized by terraces with monoatomic steps is obtained after potentiodynamic reduction down to {minus}1.12 V/standard hydrogen electrode (SHE), of the electropolished surface exposed to air. The formation of a single Cu{sub 2}O passive layer at 0.03 V/SHE proceeds first by a roughening of the steps assigned to a locally blocked step flow process due to a competition between dissolution and preferential nucleation of the oxide at the steps. The observed oxide nuclei are 2--3 nm wide and about one atomic plane high. This process leads to the complete coverage of the terraces by a grain-like structure of the oxide film. The initial terrace topography is completely altered. Thickening of this oxide layer leads to unstable scanning tunneling microscope imaging, despite the presence of a subband in the bandgap of the oxide. Duplex passive films Cu{sub 2}O{vert_bar}CuO-Cu(OH){sub 2}, produced at 0.98 V/SHE, are characterized by a grain-like structure with no detectable evidence of crystallinity. The lateral size of the grains ranges from 1 to 5 more » nm. The measured height difference is {le}1.5 nm. Stable imaging occurs via electron tunneling in the conduction band of the passive film. A metal surface topography can be recovered by potentiodynamic reduction of the oxide film down to {minus}0.92 V/SHE. The smallest terraces are eliminated by step coalescence in these oxidation/reduction treatments, which leads to steeper surface profiles. « less