Carbon quantum dot modified clinochlore as a green support for the formation and stabilization of palladium nanoparticles in aqueous Suzuki-Miyaura coupling.

A sustainable and efficient heterogeneous palladium catalyst was developed by supporting palladium nanoparticles on clinochlore as a naturally abundant clay mineral modified with carbon quantum dots (CQDs). The clinochlore-CQD support was synthesized via a straightforward hydrothermal method using citric acid and urea as the CQD precursors. The presence of CQDs provides an abundance of surface functional groups, facilitating the effective reduction and stabilization of Pd(0) from a PdCl2 precursor. Comprehensive characterization of the clinochlore-CQDs@Pd nanocomposite confirmed that the lamellar structure of the clinochlore remained intact and Pd nanoparticles homogeneously distributed without aggregation. The catalytic performance of the composite was evaluated in the Suzuki-Miyaura cross-coupling of aryl halides with arylboronic acids. The catalyst exhibited high activity toward a broad range of aryl iodides, bromides, and chlorides, delivering biaryl products in high to excellent yields under mild conditions in aqueous media. Furthermore, the key role of CQDs in enhancing palladium stabilization and catalytic efficiency was demonstrated. The catalyst was successfully recycled over several runs, with post-reaction characterization confirming its robust structural stability.