IN-SITU STM STUDY OF LOCAL DISSOLUTION/DEPOSITION AND ANODIC DISSOLUTION OF CU(111) ELECTRODE IN SULPHURIC ACID SOLUTION

摘要

In-situ STM has been employed to study Cu(111) surface in aqueous sulphuric acid. In agreement with previous work we observe a short-range periodicity resulting from the ordered (bi)sulphate ad-layer and a long-range periodicity (Moire pattern). We focus here on the anodic dissolution and restructuring of the surface in the presence of adsorbed (bi)sulphate. We have been able to image the Moire pattern of the (bi)sulphate covered surface during such dynamic processes and hence determine preferential etching and re-deposition directions. During both Cu local and anodic dissolution processes step edges running along the Moire pattern are most stable. The Moire pattern does not run along the close packed directions of the (bi)sulphate ad-layer so the step reorientation on (bi)sulphate covered Cu(111) is significantly different to the behaviour on the chloride covered surface. We thus identify a different mechanism for dissolution re-deposition kinetics on (bi)sulphate covered surfaces in which the Moire pattern steers the dissolution or growth directions.