A porous and low-density protective film on a steel surface in the corrosive environment can undergo deterioration even in the presence of organic inhibitors due to infiltration of aggressive ions into the pinholes and/or pores. This phenomenon is related to the localized corrosion that takes place even in the presence of an optimal concentration of organic corrosion inhibitors in the given medium. To overcome this issue, we have designed an organic protective film on a steel surface with the help of titania nanoparticles (TNPs) combined with an organic corrosion inhibitor derived from Aganonerion polymorphum leaf extract (APLE), all to be studied in a simulated ethanol fuel blend (SEFB). The TNPs with varied diameters and concentrations have been studied for examining their effect on the inhibition capacity of 1000 ppm APLE on the steel surface in SEFB medium using electrochemical and surface analysis techniques. Enhanced corrosion inhibition of the surficial film was observed in the presence of both the APLE inhibitor and small amounts of TNPs. A direct agreement was observed between the experimental and molecular dynamics theoretical investigations showcasing high binding energy between inhibitor molecules and steel substrates, resulting in a much higher adhesion of the protective film, good thermal stability of the adsorbent film, and electron abundance for the supply of steel substrate of inhibitor species.

The main aim of this study is to investigate Aganonerion polymorphum leaf-ethyl acetate extract (APL-EAE) and its inhibiting effect for steel in ethanol fuel blend. The immersion test, electrochemical and surface analysis techniques were successfully carried out in this research. Scanning electron microscope images indicated that the ethanol fuel blend induced pitting corrosion of steel. Remarkably, the surface of the sample containing 1000 ppm APL-EAE is smoother than the others submerged in different conditions. The electrochemical impedance spectroscopy result shows that APL-EAE has formed a good protective layer, preventing corrosive factors from hitting the steel surface. The potentiodynamic polarization data argue that the corrosion inhibition efficiency was strengthened with the increase of APL-EAE concentration. The Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy demonstrated less intensity of Fe peaks, higher intensity of C_1s peak and the appearance of organic peaks (N_1s, P_2p, O_1s) from specimens with and without APL-EAE addition. Therefore, the results suggest the formation of the protective film on steel surface and affirm that APL-EAE has served as an effective corrosion inhibitor for steel in ethanol fuel blend.

An improved photocatalytic activity of semiconductor materials using incorporation of the noble metals such as Ag, Au, and Pt is a promising technology. In this study, Ag nanoparticle-TiO₂ nanotube structures (Ag-TNTs) have been investigated as a photocatalyst in different irradiation conditions using different characterization techniques. The results indicate that Ag nanoparticles dispersed uniformly on the TNTs’ surface without any change in TNTs’ morphology. In addition, Ag-TNTs exhibited lower photoactivity than the TNTs under UV irradiation. In contrast, Ag-TNTs increased the photoactivity in comparison with TNTs and the photocatalytic performance under sunlight irradiation. These phenomena could be contributed to the appearance of Ag nanoparticles on the nanotube surface.