In the present work, we represent two thiazolidinediones, namely (Z)-5-(4-methoxybenzylidene) thiazolidine-2,4-dione (MeOTZD) and (Z)-5-(4-methylbenzylidene) thiazolidine-2,4-dione (MeTZD), as corrosion inhibitors for carbon steel (CS) in 1.0 M HCl solution. Techniques for gravimetric methods, electrochemical measurements, and morphological characterization were used to conduct experimental evaluations. Additionally, calculations based on the fundamental principles of Density Functional Theory (DFT) were employed to simulate inhibitor–iron interactions. Experimental results indicated that investigated inhibitors can significantly enhance the corrosion resistance of CS, reaching a performance of 95% and 87% at 5 × 10⁻³ mol/L of MeOTZ and MeTZD, respectively. According to gravimetric and electrochemical experiments, inhibitor molecules obstruct corrosion reactions by adhering to the CS surface, which follows the Langmuir isotherm model. On the other hand, the morphological analysis showed a well-distinguished difference between unprotected and protected CS surfaces as a result of the inhibitors’ addition to HCl. Projected density of states and interaction energies obtained from first-principles DFT simulations indicate that the studied molecules form covalent bonds with iron atoms through charge transfer.

Copper is the third-most-produced metal globally due to its exceptional mechanical and thermal properties, among others. However, it suffers serious dissolution issues when exposed to corrosive mediums. Herein, two thiazolidinedione derivatives, namely, (Z)-5-(4-methylbenzylidene)thiazolidine-2,4-dione (MTZD) and (Z)-3-allyl-5-(4-methylbenzylidene)thiazolidine-2,4-dione (ATZD), were synthesized and applied for corrosion protection of copper in 3.5 wt.% NaCl medium. The corrosion inhibition performance of tested compounds was evaluated at different experimental conditions using electrochemical impedance spectroscopy (EIS), potentiodynamic polarization curves (PPC) and atomic force microscopy (AFM). EIS results revealed that the addition of studied inhibitors limited the dissolution of copper in NaCl solution, leading to a high polarization resistance compared with the blank solution. In addition, PPC suggested that tested compounds had a mixed-type effect, decreasing anodic and cathodic corrosion reactions. Moreover, surface characterization by AFM indicated a significant decrease in surface roughness of copper after the addition of inhibitors. Outcomes from the present study suggest that ATZD (IE% = 96%) outperforms MTZD (IE% = 90%) slightly, due to the presence of additional –C₃H₅ unit (–CH₂–CH = CH₂) in the molecular scaffold of MTZD.

Rational design and simple synthesis of multifunctional electrocatalysts have significant implications across various scientific and industrial fields. In this work, we successfully synthesized nickel sulfide catalysts featuring a one-dimensional porous nanorod morphology (NiS-NRs) through a hard-template-high-temperature calcination approach. In this method, nickel-dimethylglyoxime complex nanorods ((DMG)₂Ni) served as a precursor and inexpensive thiourea as a sulfur source. The urea electrooxidation reaction (UEOR) in water electrolysis presents an opportunity to replace the kinetics-limited oxygen evolution reaction (OER), offering an energy-efficient means of hydrogen production. For the urea electrooxidation reaction, an overvoltage of 1.37 V (versus RHE) was required to achieve a current density of 10 mA cm⁻². Similarly, for the hydrogen evolution reaction, a modest overvoltage of 255 mV resulted in a current density of 10 mA cm⁻². In a two-electrode system, the NiS-NR‖NiS-NR urea electrolyzer demanded a potential of 1.24 V at 1 mA cm⁻², surpassing the aqueous electrolyzer requirement (1.41 V vs. RHE). Meanwhile, the as-prepared NiS-NRs also showed a high nitrate reduction reaction (NO₃RR) performance, with a high NH₃ yield rate (0.513 mmol h⁻¹ mg_cat ⁻¹) at −0.65 V vs. RHE. These results verified that the high-temperature calcination process employing a hard template effectively preserved the one-dimensional morphology of the initial template. The resultant nickel sulfide catalysts exhibit commendable electrocatalytic performance for urea electrooxidation, hydrogen evolution and nitrate reduction reactions.