Mechanistic understanding of the functionality of organic corrosion inhibitors in acidic media is essential to knowledge-based performance optimization. In this study, we address a key issue hindering progress in this area, namely the chemical nature of the corrosion inhibitor/substrate interface. X-ray photoelectron spectroscopy (XPS) is employed to reveal the surface termination of carbon-steel, following immersion in 1 M hydrochloric acid inhibited with 2mercaptobenzimidazole (MBI). Core level spectra indicate that the termination varies as a function of MBI concentration, with the interface consisting of MBI bound to film-free carbon-steel on highly inhibited substrates.

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Electrochemical measurements and substrate analysis have been employed to probe the corrosion inhibition performance of 2-mercaptobenzimidazole (MBI) for carbon-steel in 1 M, 0.1 M, and 0.01 M HCl. Data demonstrate that the inhibition efficiency of MBI is essentially independent of HCl concentration. Moreover, it is concluded that the presence of MBI impedes the cathodic reduction of dissolved O 2 to a lesser extent than H + . X-ray photoelectron spectra indicate that substrate termination varies as a function of both HCl and MBI concentration, with the interface consisting of MBI bound to film-free carbon-steel on highly inhibited substrates.

Pd and PdM (M = Fe and Co) nanostructured electrocatalysts were synthesized by the impregnation method and supported on carbon black Vulcan XC-72R for the formic acid oxidation reaction, FAOR, in acid medium. Nitrates or chlorides were used as Fe and Co precursors to study the counter ion role on the physicochemical features and electrochemical performance of the electrocatalysts. TEM analysis showed that PdM was deposited on the carbon material with a particle size around 2-3 nm. From XRD, peaks associated with the fcc palladium planes were observed along with evidence of PdM alloy formation, particularly when the nitrate salts were used as metal precursors. Furthermore, XPS analyses indicated that nitrates promote the metal oxide formation to a greater extent than chlorides, mainly for Pd.PdCo electrocatalyst obtained from nitrates exhibited the highest performance for FAOR with a steady state current density of 451 and 313 µA cm -2 at 200 and 400 mV respectively, which is in both cases, 3 times larger than that developed for a commercial Pd/C catalyst.