Influence of copper surface pretreatment on the kinetics of oxygen reduction reaction in 0.5 M NaCl solution: Surface characterization and electrochemical studies

The study of oxygen reduction reaction (ORR) in 0.5 M NaCl on copper revealed that oxygen reduction reaction rates are markedly influenced by the surface condition and increased in the following order: covered with PDTC < pre-reduced < passivated surfaces. On pre-reduced and passivated surfaces, the ORR proceeded via a four electron pathway limited by oxygen diffusion. When the surface is passivated, the ORR is influenced by a combination of the reduction of copper oxide and the normal kinetics of ORR at a pre-reduced surface. The partial reduction of Cu2O oxide enhances the ORR kinetics. A surface covered with PDTC represents the least reactive site towards ORR process. The current densities decreased significantly due to the limitation of O2 access to the surface by the formation of a protective barrier layer. PDTC molecules are bonded on copper surface and form an inhibitive adsorption layer, which plays a major role in slowing down O2 reduction by blocking the active cathodic sites

Elaboration and Physico-Mechanical Characterization of a New Eco-Mortar Composite Based on Magnetized Water and Fly Ash

This study examines the flexural strength and compressive strength of the mortars, which were mixed with the electromagnetic field treated water (EMFTW) and contained fly ash. EMFTW was obtained by passing the tap water through an electromagnetic field. The test variable was the fly ash content in place of cement and the water treated with EMFTW in place of the tap water. The results show that the flexural and compressive strength of the mortar samples mixed with MFTW is 12.56% and 15.8% higher than that prepared with the tap water, respectively. It was also found that the magnetized water improves the resistance to bending and compression by 12.67% and 4.35% to that prepared with the tap water and 10% fly ash instead of cement

Adsorption and Inhibition Mechanisms of New Pyrazole Derivatives for Carbon Steel Corrosion in Hydrochloric Acid Solutions Based on Experimental, Computational, and Theoretical Calculations

The study aims to synthesize two green pyrazole compounds, N-((1H-pyrazol-1-yl)methyl)-4-nitroaniline (L4) and ethyl 5-methyl-1-(((4-nitrophenyl)amino)methyl)-1H-pyrazole-3-carboxylate (L6), and test their action as corrosion inhibitors for carbon steel (CS) in a 1 M HCl solution. Both chemical and electrochemical methods, namely, gravimetric measurements (WL), potentiodynamic polarization (PDP), and electrochemical impedance spectroscopy (EIS), were used to assess the efficiency of the investigated molecules. DFT calculations at B3LYP/6-31++G (d, p) and molecular dynamics simulation were used to carry out quantum chemical calculations in order to link their electronic characteristics with the findings of experiments. The organic products exhibited good anticorrosion ability, with maximum inhibition efficiencies (IE %) of 91.8 and 90.8% for 10–3 M L6 and L4, respectively. In accordance with PDP outcomes, L6 and L4 inhibitors act as mixed-type inhibitors. Assessment of the temperature influence evinces that both L4 and L6 are chemisorbed on CS. The adsorption of L4 and L6 on CS appears to follow the Langmuir isotherm. Scanning electron microscopy and UV–visible disclose the constitution of a barrier layer, limiting the accessibility of corrosive species to the CS surface. Theoretical studies were performed to support the results derived from experimental techniques (WL, PDP, and EIS)