Effect of the pH in the growth of benzotriazole model layers at realistic environmental conditions

Abstract

The growth of benzotriazole (BTAH) via solution deposition onto copper monolayers prepared via underpotential deposition (UPD) on Au(111)/mica substrates has been investigated using X-ray photoelectron spectroscopy (XPS) and ambient scanning tunnelling microscopy (STM) as a function of solution pH and immersion time. Adsorbed species have been found sensitive to the solution pH with a higher benzotriazole surface concentration following deposition from an acidic environment. Although the layers prepared at different pH are chemically different, as highlighted by XPS, similar morphologies are recorded via STM. These results are critically discussed in the light of some of the adsorption models previously reported.

On-surface condensation of low-dimensional benzotriazole–copper assemblies

“…Many studies focussing on solution chemistry report the presence of Cu(I)-BTA compounds [5,38,53,[56][57][58]. Often the presence of Cu(II) in those samples has been attributed to post oxidation due to exposure to atmosphere [60][61][62][63].…”

Copper Adatoms Mediated Adsorption of Benzotriazole on a Gold Substrate

“…This suggests that the morphology of the low index surfaces might not have an adequate availability of adatoms by, e.g., not exposing enough defective sites, to produce the necklace polymer. On the one hand this indicates the necessity to work on more realistic substrates [76][77][81][82][83], and to investigate further the role of copper adatoms.…”

“…After preparation (panels b), a Cu 2p 3/2 peak is recorded at 931.9 eV (with a full width at half maximum, fwhm, of 1.2 eV). Since Cu (0) and Cu(I) have similar binding energy (BE) [72][73][74], it is difficult to determine unambiguously the copper oxidation state a priori, and often the evaluation of the copper oxidation state is made considering the Cu LMM Auger lines [75][76][77][78][79]. However, as very reactive copper atoms are deposited, the symmetric and narrow shape of the observed Cu 2p 3/2 peak and its BE value indicate that copper is more likely to be in the +1 oxidation state.…”

“…The absence of a peak at higher BE and of a satellite structure at ca. 945 eV [72][73][74][75][77][78][79] (not shown) rule out the presence of Cu(II). As a comparison, upon adsorption of copper on Au(1 1 1), a partial charge transfer from the copper atoms to the gold surface occurs [43][44][45], but a formal net charge cannot be attributed to copper.…”

Chloride-Assisted Corrosion of Copper and Protection by Benzotriazole

“…4 Benzotriazole (BTAH), because of its excellent inhibition efficiency, has been extensively used as a corrosion inhibitor of copper and copper alloys in a variety of aggressive environments. 3−10 Extensive work on this topic has been reported in a variety of environmental conditions, including pH, 5,11 ion species and concentration, 12,13 crystalline substrates with different Miller indices and oxidation state, 14−20 temperature, 21,22 and potential at the electrified copper surface. 5,6,23 Several models have been proposed to understand the adsorption dynamics as well as the configuration of the passivating film formed by BTAH on the copper surface.…”