Photo-Assisted Synthesis of a Pd-Ag@CQD Nanohybrid and Its Catalytic Efficiency in Promoting the Suzuki-Miyaura Cross-Coupling Reaction under Ligand-Free and Ambient Conditions.

Supported bimetallic nanoparticles are very promising heterogeneous catalysts for carbon-carbon cross-coupling reactions, though reports focusing on their synergistic activity for promoting such reactions are very limited. In the current study, bimetallic Pd-Ag hybrid nanoparticles supported on carbon quantum dots (CQDs), Pd-Ag@CQDs, were synthesized by a facile and fast UV-light-driven (365 nm) one-pot protocol for the first time to investigate such a synergistic activity. The physico-chemical structural features of the Pd-Ag@CQD nanohybrid were evaluated by UV-vis, Fourier transform infrared, X-ray diffraction, electron-dispersive X-ray, and transmission electron microscopy analyses. The nanohybrid was found to have dimensions in the range of ca. 3-5 nm. The bimetallic Pd-Ag@CQD nanohybrid was utilized as an efficient heterogeneous catalyst for promoting the Suzuki-Miyaura coupling reaction with aryl bromides and aryl chlorides under ligand-free and ambient conditions. The synergistic activity of the components of the nanohybrid induced catalytic enhancement of the cross-coupling reaction in terms of short reaction times (<1 h) and high yields (>90%). The heterogeneous character of the nanohybrid system also enabled easy separation and recyclability (up to six cycles).