Synergistic enhancement of chitosan via molecular modification and MXene nanosheets for green, high-efficiency corrosion inhibition of low-carbon steel.

To address chitosan's (CS) inherent limitations as a corrosion inhibitor-namely its weak adsorption capacity and inadequate hydrophobicity-this study used a Schiff base reaction to graft 5-hydroxymethylfurfural (HMF) onto the chitosan backbone, markedly improving its film-forming capabilities. Then, two-dimensional MXene (Ti3C2TX) nanosheets were incorporated to fabricate a CS-HMF-MXene composite. This engineered composite provides exceptional corrosion protection for low-carbon steel through a trifold synergistic mechanism: chemical adsorption, a physical barrier effect, and the formation of a superhydrophobic interface. The corrosion inhibition efficiencies (IE) of CS, CS-HMF, and CS-HMF-MXene in a 3.5 wt% NaCl solution were evaluated through electrochemical measurements and surface characterization techniques. At an inhibitor concentration of 200 ppm, the CS-HMF-MXene composite achieves a maximum IE of 87.86 %. After 72 h immersion the surface roughness declined from 4.96 μm (blank) to 1.32 μm and the water contact angle climbed from 53.1° to 91.0°, confirming a denser, more hydrophobic film. Molecular dynamics simulations corroborate these experimental results, demonstrating that the inhibitor adsorbs in a stable parallel configuration on the Fe (110) surface, with binding distances <3.5 Å., thereby effectively blocking the penetration of corrosive agents. This work showcases a synergistic strategy that combines molecular-level chitosan modification with MXene integration to create high-performance, environmentally friendly corrosion inhibitors for low-carbon steel.