A Study of Adsorption Forms of 1,2,3-Benzotriazole on the Surface of Copper by the Methods of Raman Spectroscopy and DFT Modeling

The paper presents the results of a study of 1,2,3-benzotriazole (BTA) films formed on a real copper surface under various conditions. It has been established that BTA molecules, depending on the conditions, form adsorption (Cu–BTA_ads) or surface-associated (Cu–BTA_surf) films. The coordination forms of BTA molecules on the copper surface were established using Raman spectroscopy and density functional theory (DFT) modeling. By counter synthesis, complex compounds BTA–Cu²⁺ were obtained in aqueous solutions at different pH values and their properties were studied using IR and Raman spectroscopy. On a real copper surface, adsorption and surface-associated films of copper and 1,2,3-benzotriazole complexes were formed at different pH values and temperatures, and their structure and properties were studied. The SERS effect was registered and its explanation was given based on the differences in the structure of the synthesized complexes of BTA–Cu²⁺, Cu–BTA_ads adsorption films, and surface-associated Cu–BTA_surf structures. Quantum-chemical modeling of possible adsorption of Cu–BTA_ads and surface-associated Cu–BTA_surf structures was carried out using the DFT method, and a DFT calculation of their Raman spectra was performed. The geometries of surface structures have been established. Energy states of Cu–BTA_ads and Cu–BTA_surf structures were analyzed. It is shown that the predictions of DFT modeling successfully correlate with experimental results.