Pd Nanoparticles\non Carbon Supports as Electrocatalysts\nfor the Oxygen Reduction Reaction

Abstract

The development of efficient catalysts for proton exchange\nmembrane\nfuel cells (PEMFCs) is crucial for their commercial viability. This\nstudy introduces a method for synthesizing Pd nanoparticles on carbon\nsupports as electrocatalysts using microbial synthesis, specifically\nemploying the bacterium Shewanella oneidensis MR-1. The so-produced catalysts exhibit enhanced catalytic activity\nand stability for the oxygen reduction reaction (ORR). The microbial\nsynthesis approach offers advantages, such as high purity, cost-effectiveness,\nand environmental friendliness. Additionally, the use of sodium alginate\n(SA) hydrogel in the synthesis process further improves the catalyst’s\nperformance due to its metal chelating properties. The resulting Pd/C\nelectrocatalysts, especially those synthesized with a composite matrix\nof SA and CaCO₃, demonstrate superior ORR performances\noutperforming that of commercial Pd/C catalysts. It was found that\nthe composite substrate affected the palladium recovery rate, whose\nincreasing palladium absorption, refined particle size, improved graphitization\ndegree, and increasing pyridinic-<i>N</i> of the resultant\ncatalyst synergistically enhanced the availability of active centers\nthat eventually contributed to the superior ORR performances. This\nresearch paves the way for the development of high-performance and\ncost-effective catalysts for PEMFCs.