Microbial synthesis of Pd–Pt alloy nanoparticles using Shewanella oneidensis MR-1 with enhanced catalytic activity for nitrophenol and azo dyes reduction

Bimetallic nanoparticles (NPs) often exhibit improved catalytic performance due to the electronic and spatial structure changes. Herein, a novel green biosynthesis method for Pd–Pt alloy NPs using Shewanella oneidensis MR-1 was proposed. The morphology, size and crystal structure of Pd–Pt alloy NPs were studied by a suite of characterization techniques. Results showed Pd–Pt alloy NPs were successfully synthesized inside and outside the cell. The biosynthesized Pd–Pt alloy NPs were polycrystalline and face-centered-cubic structure with the particle size ranged from 3–40 nm. Furthermore, the catalytic experiment demonstrated that the Pd–Pt alloy NPs exhibited the highest performance for the catalytic reduction of nitrophenol and azo dyes compared with the as-synthesized Pd and Pt monometallic NPs. This enlarged catalytic activity resulted from the synergistic effect of Pd and Pt element. Thereby, this paper provided a simple biosynthesis method for producing bimetallic alloy nanocatalyst with superior activity for contaminant degradation.