Moiré Structure of the 2-Mercaptobenzothiazole Corrosion Inhibitor Adsorbed on a (111)-Oriented Copper Surface.

Xiaocui Wu,Frédéric Wiame,Philippe Marcus,Vincent Maurice

doi:10.1021/acs.jpcc.0c04083

Abstract

The adsorption of 2-mercaptobenzothiazole (2-MBT) vapor on a Cu(111) surface under ultra-low pressure was investigated. For an exposure of 45 L at 150 °C, a Moiré pattern was observed as a result of the superposition of an underlying R30° structure and an outer layer compressed by 18% and rotated by 1.2°. The Moiré pattern was rich in S bonded to Cu as a result of molecular decomposition and partial desorption and was transformed to a R19.1° structure when the sample temperature was increased above 250 °C during deposition. This pre-adsorbed Moiré structure led to the sharp decrease of the oxidation kinetics, which better protects copper against corrosion than the non-ordered 2-MBT monolayer formed at room temperature. Upon further exposure to 2-MBT at room temperature, an equivalent monolayer of the molecule was adsorbed on the Moiré structure at saturation whereas a multilayer was formed for the direct deposition on Cu(111) at room temperature.

Highlights

( 3 × 3 )R30° structure and an outer layer compressed by 18% and rotated by 1.2°
It was mechanically polished to 0.25 μm, electropolished in phosphoric acid, and prepared in the ultra-high vacuum (UHV) system by cycles of ion sputtering (PAr = 1 × 10−5 mbar, 600 V, and 20 mA for 30 min) and annealing (600 °C for 30 min) until a clean copper surface was obtained, i.e., no contamination was shown by Auger electron spectroscopy (AES), a sharp (1 × 1) pattern was observed by low-energy electron diffraction (LEED), and large and flat terraces were observed by scanning tunneling microscopy (STM)
The adsorption of 2-MBT on Cu(111) at ultra-low pressure was investigated at mild temperature by STM, X-ray photoelectron spectroscopy (XPS), AES, and LEED

Summary

Introduction

The Moiré pattern was rich in S bonded to Cu as a result of molecular decomposition and partial desorption and was transformed to a ( 7 × 7 )R19.1° structure when the sample temperature was increased above 250 °C during deposition. This pre-adsorbed Moiré structure led to the sharp decrease of the oxidation kinetics, which better protects copper against corrosion than the non-ordered 2-MBT monolayer formed at room temperature. Upon further exposure to 2-MBT at room temperature, an equivalent monolayer of the molecule was adsorbed on the Moiré structure at saturation whereas a multilayer was formed for the direct deposition on Cu(111) at room temperature. The results provide new insight on the chemical and structural interaction between the inhibitor molecule and the copper surface and contribute to the design of new inhibitors that better protect the metals

Methods

Results

Conclusion