Corrosion has been frequently recognized as failure's root cause for diverse engineering components like those associated to production lines, like in boiling water reactor piping systems (1). It is important that several electrochemical techniques help conjointly to elucidate some of the corrosion specificities, like localized corrosion of traditional materials. Pitting corrosion has been usually reported to affect stainless steels because it engages more frequent than not, second phase particles that precipitate out at the matrix and the grain boundary network, thereby consuming alloying elements that, for example, participate on sustaining passivity. Thermally-dependent fabrication operations such as welding bring about sensitization, particularly within the 450 to 700 ºC range. Exposure propitiates nucleation and growth of chromium carbide networks: this makes the boundaries and neighboring areas sensitive to depletion. Thus the precipitates are directly suspect of significant decrements in protective potential as the chromium has been chemically bound to carbon, thereby decreasing the surface passivating abilities. Therefore, the present work reports the electrochemical and microscopy results obtained after immersing the heat treated SS304 samples for diverse periods in a suitable electrolyte to studying their potentiodynamic polarization and EIS behaviors.

To reduce the CO₂ concentration in the atmosphere, its conversion to different value-added chemicals plays a very important role. Nevertheless, the stable nature of this molecule limits its conversion. Therefore, the design of highly efficient and selective catalysts for the conversion of CO₂ to value-added chemicals is required. Hence, in this work, the CO₂ adsorption on Pt_4-xCu_x (x = 0–4) sub-nanoclusters deposited on pyridinic N-doped graphene (PNG) was studied using the density functional theory. First, the stability of Pt_4-xCu_x (x = 0–4) sub-nanoclusters supported on PNG was analyzed. Subsequently, the CO₂ adsorption on Pt_4-xCu_x (x = 0–4) sub-nanoclusters deposited on PNG was computed. According to the binding energies of the Pt_4-xCu_x (x = 0–4) sub-nanoclusters on PNG, it was observed that PNG is a good material to stabilize the Pt_4-xCu_x (x = 0–4) sub-nanoclusters. In addition, charge transfer occurred from Pt_4-xCu_x (x = 0–4) sub-nanoclusters to the PNG. When the CO₂ molecule was adsorbed on the Pt_4-xCu_x (x = 0–4) sub-nanoclusters supported on the PNG, the CO₂ underwent a bond length elongation and variations in what bending angle is concerned. In addition, the charge transfer from Pt_4-xCu_x (x = 0–4) sub-nanoclusters supported on PNG to the CO₂ molecule was observed, which suggests the activation of the CO₂ molecule. These results proved that Pt_4-xCu_x (x = 0–4) sub-nanoclusters supported on PNG are adequate candidates for CO₂ adsorption and activation.

A process control agent is an organic additive used to regulate the balance between fracturing and mechanical kneading, which control the size of the as-milled particles. Tributyl phosphate (TBP) is evaluated to act as surface modifier of PbTe, and it is compared with the results obtained using formaldehyde (CH₂O). In order to elucidate the nature of the interaction between TBP and the PbTe surface, global and local descriptors were calculated via the density functional theory. First, TBP and CH₂O molecules are structurally optimized. Then, vertical ionization energies as well as vertical electron affinities are calculated to elucidate how both molecules behave energetically against removal and electron gain, respectively. The results were compared with those obtained from the electrostatic potential mapped on the van der Waals isosurface. It is inferred that the theoretical insights are useful to propose adsorption modes of TBP and CH₂O on the PbTe surface, which are usable to rationalize the facets exposed by PbTe after the surface treatment. The optimized structures of the compound systems showed a close correlation between the surface energy shift (Δγ) and the PbTe facets exhibited. Finally, a Wulff construction was built to compare the usage of TBP and CH₂O molecules in PbTe morphology.

La corrosión es uno de los principales problemas del deterioro en componentes, herramentales, equipos e inclusive a nivel estructural, ejemplo de esto son los aceros al carbono. En el presente trabajo se estudió la capacidad de inhibición a la corrosión de un extracto orgánico biodegradable proveniente de la planta del Nopal (Opuntia ficus-indica) para la protección del acero al carbono tipo AISI 1018, al agregar el 50% v/v del extracto de Nopal (EN) en una solución de H2SO4 (0,6 mol.l-1). Se utilizaron las técnicas de Resistencia a la Polarización (LPR) y Espectroscopía de Impedancia Electroquímica (EIS) para determinar la eficiencia de inhibición (IE) a temperatura ambiente durante 24 h y obtener las velocidades de corrosión (Vcorr), posteriormente se llevó a cabo la evaluación metalográfica para registrar el daño superficial. Los resultados mostraron una reducción de la Vcorr con una IE máxima del 84% al adicionar el inhibidor orgánico EN.