Ag/Pd bimetallic sites embedded in g-C ₃ N ₄ nanosheets synergistically catalyze Suzuki coupling and nitroaromatic reduction reactions

Transition metal (Pd) mediated C-C coupling reactions are key synthetic approaches among organic reactions and have become an integral part of synthetic endeavors. This study employs high-temperature pyrolysis to embed AgPd dual active sites within graphitic carbon nitride (g-C₃N₄), enabling highly efficient carbon-carbon coupling reactions and reduction of nitroaromatics. The prepared AgPd-C₃N₄ showed excellent catalytic performance in Suzuki-Miyaura coupling and transfer hydrogenation reactions of nitroaromatics. The reaction rate and selectivity of AgPd-C₃N₄ were superior to those of Pd-C₃N₄ and Pd-C₃N₄ under mild conditions. Both characterization results and density-functional theory calculations indicate that the abundant Ag inside AgPd-C₃N₄ can provide electrons to Pd in the adjacent sites, which significantly increases the reaction rate of the oxidative addition step during the Suzuki-Miyaura coupling reaction. The π-π conjugation effect between aryl halides and g-C₃N₄ also helps to accelerate the reaction. Under the same conditions, the yield of the Suzuki-Miyaura coupling reaction catalyzed by AgPd-C₃N₄ (98%) exceeded that of Pd-C₃N₄ (79%). Furthermore, the synergistic interaction between the bimetallic centers improved the catalytic activity of AgPd-C₃N₄ in nitroaromatic transfer hydrogenation reactions. The formation of Ag-N_x and Pd-N_x coordination bonds improved the dispersion and stability of Ag and Pd nanoparticles. This study provides a new strategy for the rational design of high-performance bimetallic catalysts based on carbon nitride.