Designing multifunctional basalt-CeO2@C3N4/epoxy novolac composite coating with outstanding corrosion resistance and CO2 gas barrier properties

The greenhouse effect caused by CO₂ emissions is becoming more and more serious, and the carbon capture, utilization and storage (CCUS) is a feasible strategy to reduce emissions. However, the corrosion problem brought by CCUS is unprecedentedly serious. In this paper, we present a composite epoxy novolac (EN) system for resisting corrosion of metals in CCUS environments. In this system, nanorod CeO₂ and nanosheet C₃N₄ are simultaneously grown on the surface of the micron sheet basalt (Bt), which are used as effective additives to improve the corrosion resistance and CO₂ gas barrier properties of EN. Only with 3 % of nanoparticles addition, a significant reduction of the gas diffusion of composite film to dry CO₂ has been observed, up to 5.88 × 10⁻¹² m²/s. This is associated with the synergistic enhancement of the physical shielding effect by the nano and micron sheets. Additionally, we found that adsorption of oxygen vacancy of CeO₂ material with CO₂ enhances the stability of corrosion resistance. Therefore, the |Z|_0.01 Hz of the Bt-CeO₂@C₃N₄/EN coating is above 10⁶ Ω cm² higher than that of the EN coating after 25 days of immersion in a 3.0 MPa CO₂ aqueous solution at 70 °C. Overall, the anti-corrosion coating system combines long-lasting water resistance and low CO₂ gas transmission in harsh corrosive environments, and thus has a high potential for CCUS applications.