pH-Responsive Containers Based on Modified Hollow TiO2 for Active and Passive Protection of Carbon Steel

In this study, TiO2 containers with an empty core and a mesoporous shell were successfully synthesized via hydrothermal reaction. The as-prepared TiO2 was used as carrier to load the corrosion inhibitor 2-mercaptobenzimidazole (MBI). The outer shell of inhibitor-loaded containers was modified by a SiO2 film, which was obtained from hydrolysis of tetraethyl orthosilicate (TEOS) and (3-aminopropyl) triethoxysilane (APTES). The structure of the TiO2 containers was studied using X-ray diffraction (XRD) analysis, field emission scanning electron microscopy (FESEM), and Fourier transform infrared (FTIR) spectrometry. The release behavior of the corrosion inhibitor was investigated using UV-visible spectroscopy. The corrosion protection performance of the water-based epoxy coating with modified TiO2 containers was studied by using electrochemical impedance spectroscopy (EIS) and a scanning Kelvin probe (SKP). The coating with modified TiO2 containers demonstrated enhanced film barrier properties compared with blank coating. Results obtained from SKP measurements confirmed active corrosion protection performance of the studied TiO2 containers.