Biomass-derived carbon quantum dots for the fabrication of a durable, self-cleaning, and corrosion-resistant superhydrophobic coating on steel

Abstract The enhancement of durable and environmentally friendly superhydrophobic (SHP) coatings for metal protection remains a significant challenge. This study presents a green and effective strategy for fabricating a robust SHP coating on steel by integrating carbon quantum dots derived from Conocarpus lancifolius biomass (denoted C-CQDs). The pivotal innovation lies in the incorporation of C-CQDs during a one-step electrodeposition process, which fundamentally alters the coating’s growth mechanism to promote nucleation, resulting in a dense, finely granular morphology. This unique structure, confirmed by SEM and AFM, achieved a substantial surface roughness of 335.6 nm and exceptional water repellency, having a water contact angle of 167° and a water sliding angle of 1°. Compared with the C-CQD-free SHP coating, the C-CQD-containing coating showed improved abrasion tolerance under the present test conditions (maintaining superhydrophobicity after 900 mm of abrasion) and outstanding chemical stability across a wide pH range (1–13). Electrochemical tests revealed a remarkable corrosion protection efficiency of 93.1%, a significant increase from the 78.5% efficiency of the C-CQD-free SHP coating. This work not only introduces a sustainable source for high-performance nanomaterials but also provides a versatile strategy for designing next-generation functional coatings with integrated anti-corrosion, self-cleaning, and mechanical resilience for practical industrial applications.