Biogenic Synthesis of Pd-Based Nanoparticles with Enhanced Catalytic Activity

Searching efficient sustainable approaches for the metal nanoparticles (NPs) synthesis has become a research focus. Bioreduction with metal-reducing bacterium at ambient temperature provides a green route for metal NPs synthesis, especially for precious metals. In this work, activated Pd NPs were synthesized by contacting Pd2+ solution with an efficient metal-reducing Shewanella oneidensis bacterium, in which the bacterium acted as reducing, capping, and stabilizing agents, and the shape and composition of the Pd NPs could be tuned with the activation of KOH at elevated temperatures. The as-activated Pd NPs showed a favorable performance toward catalytic reduction of 4-nitrophenol (4-NP) to 4-aminophenol (4-AP), with a remarkable apparent kinetic constant of 5.0 × 10–3 s–1, which was 12 times greater than that of the raw biogenic Pd NPs, even comparable to that of the commercial 5.0 wt % Pd/C. Changes of the Pd NPs aggregates, ratio of Pd to S, and surface area of the support at different temperatures and...