Green and sustainable leaf-derived carbon dots toward greatly facilitating chloride binding of cement

Chloride-induced corrosion is one of the most critical factors limiting the durability and service life of reinforced concrete (RC) structures, and improving chloride binding capacity is therefore of great significance for extending structural durability and reducing CO 2 emissions in the cement industry. However, the practical application of chloride binding technology is still hindered by the lack of eco-friendly, low-cost, and highly dispersible nanomaterials. Herein, truly green, cost-effective, and highly dispersed leaf-derived carbon dots (CDs) are for the first time adopted to enhance chloride binding in cement pastes. Specifically, leaf-derived CDs are prepared via a one-step hydrothermal process using environmentally friendly and renewable litchi leaves as the precursor. The as-obtained CDs exhibit excellent dispersibility in simulated concrete pore solution. Notably, the incorporation of 0.2 wt% CDs increases the chloride binding capacity by 59.34 % after 28 days of immersion in 3 M NaCl solution. More importantly, the CDs-induced enhancement mechanism of chloride binding is elucidated based on a detailed investigation of phase compositions in various cement pastes. The results indicate that leaf-derived CDs accelerate cement hydration, leading to the formation of more C–S–H gel and Friedel’s salt, thereby significantly improving chloride binding. This work provides a truly green and cost-effective nanomaterial strategy to enhance the resistance of RC structures against chloride erosion, prolong their service life, and reduce CO 2 emissions in the cement industry. Moreover, these findings pave the way for a promising waste-to-resource approach for biomass valorization. • Low-cost and highly dispersed leaf-derived CDs are simply prepared. • Green leaf-derived CDs are firstly employed to improve chloride binding of cement. • 0.2 wt% leaf-derived CDs make chloride binding of cement increase by 59.34 %. • Enhancement mechanism of chloride binding in cement modified by leaf-derived CDs is revealed.