Pd nanoparticles supported on microbial cells (bio-Pd) are a sustainable alternative to conventional heterogeneous catalysts. Supported Pd nanoparticles are excellent catalysts used industrially in the synthesis of fine chemicals. However, the global demand for Pd far exceeds global supply, therefore sustainable Pd use and recycling is vital. Conventional chemical synthesis routes often require high temperatures and pressures, as well as the use of toxic chemicals. Microbes are capable of bioreducing metal precursors from solution to form metal nanoparticles at ambient temperature and pressure, without the need for toxic chemicals. Microbes can also reduce metal from waste solutions, revalorising these waste streams and allowing the reuse of precious metals. In addition, microbes can produce bimetallic Pd-based nanoparticles with enhanced catalytic properties. This project aims to bioengineer the bioreduction process to optimise the catalytic properties of bio-Pd. Our work utilises Geobacter sulfurreducens, an obligatory anaerobic Gram-negative bacterium found in the subsurface, which couples the oxidation of organic electron donors to the reduction of metal species to conserve energy for growth. G. sulfurreducens bioreduced Pd(II) to Pd(0) nanoparticles using different electron donors, and the effect of metal loading was also investigated. Inductively coupled plasma mass spectroscopy (ICP-MS) measured the removal rates of Pd from solution by the bacterium. Bio-Pd was characterised using X-ray diffraction (XRD) and transmission electron microscopy (TEM). Pd/G.sulfurreducens was shown to be effective for 4-nitrophenol reduction, producing comparable initial rates to a Pd/C commercial catalyst. In addition, PdAu bimetallic nanoparticles were produced from G. sulfurreducens bioreduction. These bimetallic particles will be characterised and compared to their monometallic counterparts for 4-nitrophenol reduction.

Biotechnological production of supported metal nanoparticles for catalysis

ACS Spring 2022

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.