One-pot biosynthesis of rGO-supported PdAu bimetallic nanoparticles as an efficient catalyst for Suzuki-Miyaura coupling reactions

PdAu bimetallic nanoparticles synthesized by bacterial cells (Bio-PdAu NPs) are receiving more and more research interest. However, its practical application is extremely limited because of the inefficient PdAu immobilization, which is critical regarding both security and process costs. This work reported one-pot biosynthesis of reduced graphene oxide (rGO)-supported PdAu NPs (Bio-PdAu@rGO) with the Shewanella oneidensis MR-1 at ambient temperature. Shewanella oneidensis MR-1 can efficiently reduce GO to rGO and produce face-centered-cubic (fcc) structural PdAu alloy NPs that uniformly embedded on bacterium and rGO. Interestingly, in situ bio-synthesized rGO significantly increased the recovery rate of PdAu NPs from 35.6% to 93.5%. Bio-PdAu@rGO displayed an efficient catalytic activity for Suzuki-Miyaura cross-coupling reactions in contrast to that as-synthesized monometallic bio-Pd NPs, with Bio-PdAu NPs significantly outperforming both. Modest to excellent conversion with 82-100% was obtained when aryl iodide and aryl bromide were used to evaluate the catalytic performance. Moreover, the catalysts had strong universality and tolerate a wide range of substituents. In summary, the small size and uniform size distribution of PdAu NPs, combined with the strong electrostatic attraction and electrical conductivity of rGO, can make Bio-PdAu@rGO an active and stable catalyst in the Suzuki-Miyaura coupling reaction.