Tannic acid-modified g-C3N4 nanosheets/polydimethylsiloxane as a photothermal-responsive self-healing composite coating for smart corrosion protection

The economic ramifications and societal detriments resulting from marine-induced corrosion on steel exhibit a nature of incalculability. The pursuit and development of efficacious corrosion-resistant coatings, designed to effectively preclude or mitigate the corrosion of steel, remain a salient challenge. Within the context of this study, a low-temperature hydrothermal methodology was employed to successfully synthesize graphitic carbon nitride (g-C3N4) photocatalytic material modified with tannic acid (TA). This composite material was incorporated, alongside polydimethylsiloxane (PDMS), as a constituent of a photothermal self-healing intelligent anticorrosive composite coating applied onto Q235 carbon steel. Experimental results derived from electrochemical impedance spectroscopy (EIS) and polarization curves corroborate that the optimal TA-CN-4/PDMS composite coating demonstrates a remarkable corrosion resistance, sustaining an impedance of 8.31 × 109 Ω·cm−2 even after a 28-day immersion in a 3.5 wt% NaCl solution. Furthermore, the TA-CN/PDMS composite coating exhibits pronounced self-healing capabilities, achieving restoration within a mere 180-minute period of light irradiation. This phenomenon is attributed to the photothermal effect of TA stimulating the motion of PDMS chains. This investigation provides a straightforward methodology for crafting photothermal self-healing anticorrosive coatings and contributes a conceptual framework for the development of efficient g-C3N4-based corrosion-resistant coatings.