Microbial synthesis of bimetallic PdPt nanoparticles for catalytic reduction of 4-nitrophenol.

Bimetallic nanoparticles are generally believed to have improved catalytic activity and stability due to geometric and electronic changes. In this work, biogenic-Pd (bio-Pd), biogenic-Pt (bio-Pt), and biogenic-PdPt (bio-PdPt) nanoparticles were synthesized by Shewanella oneidensis MR-1 in the absence or presence of quinone. Compared with direct microbial reduction process, the addition of anthraquinone-2,6-disulfonate (AQDS) could promote the reduction efficiency of Pd(II) or/and Pt(IV) and result in decrease of particles size. All kinds of nanoparticles could catalyze 4-nitrophenol reduction by NaBH4 and their catalytic activities took the following order: bio-PdPt (AQDS) ∼ bio-PdPt > bio-Pd (AQDS) > bio-Pd > bio-Pt (AQDS) ∼ bio-Pt. Moreover, the bio-PdPt (AQDS) nanoparticles could be reused for 6 cycles. We believe that this simple and efficient biosynthesis approach for synthesizing bimetallic bio-PdPt nanocatalysts is important for preparing active and stable catalysts.