ToF-SIMS, XPS and DFT study of the adsorption of 2-mercaptobenzothiazole on copper in neutral aqueous solution and corrosion protection in chloride solution

Enhanced Corrosion Inhibition of Copper in Acidic Environment by Cathodic Control of Interface Formation with 2-Mercaptobenzothiazole

“…In a work where the interface was prepared and controlled under ultra-high vacuum with deposition of the molecule from the vapour phase in ultra-low pressure conditions, it was shown that 2-MBT adsorbs on oxidefree metallic copper surfaces as well as on oxidized copper surfaces by its two sulphur atoms along with some free sulphur atoms dissociated from the molecule [24]- [26], [32], and that increasing the exposure to the molecule results in the build-up of multilayers of the organic film, in agreement with previous work with DFT modelling on metallic copper [30]. In neutral aqueous solution, it was also determined that the bonding between the 2-MBT molecule and the native oxide-covered copper surface occurred via the two sulphur atoms, forming multilayers of the organic film, and inhibiting further oxide growth [28].…”

“…However, it can be noticed that the intensity of the C7H4NS2ions is maximum at the topmost surface, whereas those of the C2Nand C2Sions are maximum in the inner part of the organic layer. This indicates, that 2-MBT forms multilayers with an inner chemisorbed layer (yellow regions on the profiles) and an outer physisorbed multilayer (pink regions on the profiles), as observed previously for adsorption of the molecule from the gas phase [22], [24], [26], [32] and in neutral aqueous solution [28]. The position of the C2Sintensity maximum is closer to the substrate than that of the C2Nintensity maximum, which indicates that 2-MBT bonds to the surface via the two S atoms, in agreement with the work of Vernack et al [28].…”

“…The S2 component at 162.8 eV corresponds to the exocyclic sulphur from the molecule, also not bonded to metallic copper. These two components can also correspond to the S atoms of the molecules bonded to copper oxides and/or forming multilayers physically adsorbed on the surface [13], [24], [28], [32]. The S3 component at 161.9 eV is sulphur bonded directly to metallic copper, which was also observed when exposing a clean metallic Cu surface to H2S [41].…”

“…Depending on the conformer of the molecule, the last H atom is bonded to either the endocyclic nitrogen or the exocyclic sulphur atom in the molecule [21], [22]. The S and N heteroatoms with high electron density are active sites that can coordinatively bond with metal atoms, enabling the molecule to strongly adsorb and to form a dense and protective film on the surface of the metal [20], [22]- [28].…”

Recovery of Rubidium Using Hydrogel Beads Encapsulating Potassium Copper Hexacyanoferrate from Saline Lake Brines

“…The Cu Auger LMM spectra are accessed since the study of the Cu 2p spectra does not enable us to differentiate between Cu (I) and Cu (0). Figure S5d displays that Cu (I) rather than Cu (0) is thought to be responsible for the characteristic peak at 570.1 eV . Before and after Rb + adsorption, the intensity of the Cu 2p peaks barely alters, demonstrating that the elemental content and the combining form remain consistent.…”