Green synthesis of Pt and Ag nanoparticles and their use towards nitric oxide abatement

• Published in: Materials research express 2014-12, Vol.1 (4), p.44001-15
• Main Authors: Castegnaro, Marcus V, Alexandre, Jéssica, Baibich, Ione M, Alves, Maria C M, Morais, Jonder
• Format: Article
• Language: English
• Subjects: Catalysis; Catalysts; Citrates; metal nanoparticles; Nanoparticles; NO abatement; Palladium; Platinum; Silver; X-rays; XPS
• ISSN: 2053-1591; 2053-1591
• DOI: 10.1088/2053-1591/1/4/044001

Pt and Ag nanoparticles (NPs) were synthesized by eco-friendly room-temperature chemical reduction routes based on trisodium citrate and L-ascorbic acid (for Pt NPs) and on gelatin and trisodium citrate (for Ag NPs). The as-prepared NPs were characterized by UV-visible absorption spectroscopy and transmission electron microscopy analyses, which confirmed the formation of sub-10 nm metal particles. Then, the colloidal solutions were used to obtain activated carbon-supported catalysts (metal AC) for direct NO decomposition. X-ray photoelectron spectroscopy and x-ray diffraction measurements proved that the NPs hosted on the support surface were present in the metallic chemical state. In situ infrared absorption spectroscopy investigations during NO reduction catalytic reactions showed that the Pt AC and Ag AC catalysts were highly active at 373 K. At 573 K, we observed different behaviors for each catalyst. While Ag AC performed similarly to the reaction at 373 K, Pt AC was found to participate in a redox mechanism, where the catalyst's active sites were oxidized by NO and reduced by carbon, thus emitting CO2 and enhancing its catalytic activity, an effect that we have also observed in carbon-supported Pd NPs.