Alkyne Semihydrogenation over Pd Nanoparticles Embedded in N,S-Doped Carbon Nanosheets

A strategy using biological materials to prepare N,S-doped carbon covering Pd nanoparticles (Pd/N,S-C) from natural silk fibroin was developed. Wet chemical reduction and carbonization were used to synthesize the Pd/N,S-C catalyst. The as-prepared catalyst showed high activity (>99%) with satisfactory selectivity (86–99%) for semihydrogenation of varied alkynes to corresponding alkenes. In addition, this work also demonstrated that the PdCx species disappeared and the effect of electron transfer between Pd and N,S-C enhanced when Pd/N,S-F (N,S-doped silk fibroin covering Pd nanocrystals) was calcined to form Pd/N,S-C, which was beneficial to improve its performance for hydrogenation. Meanwhile, the increase of specific surface area after carbonization and the embedded structure could also improve the catalytic activity of Pd/N,S-C and stereoselectivity to cis-alkenes.