Pt@Ag and Pd@Ag core/shell nanoparticles for catalytic degradation of Congo red in aqueous solution

• Published in: Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy Molecular and biomolecular spectroscopy, 2018-01, Vol.188, p.155-163
• Main Authors: Salem, Mohamed A., Bakr, Eman A., El-Attar, Heba G.
• Format: Article
• Language: English
• Subjects: Catalytic reduction; Congo red; NaBH4; Nanoparticles; Pd@Ag core/shell; Pt@Ag core/shell
• ISSN: 1386-1425
• DOI: 10.1016/j.saa.2017.07.002

Platinum/silver (Pt@Ag) and palladium/silver (Pd@Ag) core/shell NPs have been synthesized in two steps reaction using the citrate method. The progress of nanoparticle formation was followed by the UV/Vis spectroscopy. Transmission electron microscopy revealed spherical shaped core/shell nanoparticles with average particle diameter 32.17nm for Pt@Ag and 8.8nm for Pd@Ag. The core/shell NPs were further characterized by FT-IR and XRD. Reductive degradation of the Congo red dye was chosen to demonstrate the excellent catalytic activity of these core/shell nanostructures. The nanocatalysts act as electron mediators for the transfer of electrons from the reducing agent (NaBH4) to the dye molecules. Effect of reaction parameters such as nanocatalyst dose, dye and NaBH4 concentrations on the dye degradation was investigated. A comparison between the catalytic activities of both nanocatalysts was made to realize which of them the best in catalytic performance. Pd@Ag was the higher in catalytic activity over Pt@Ag. Such greater activity is originated from the smaller particle size and larger surface area. Pd@Ag nanocatalyst was catalytically stable through four subsequent reaction runs under the utilized reaction conditions. These findings can thus be considered as possible economical alternative for environmental safety against water pollution by dyes. [Display omitted] •The Pt@Ag and Pd@Ag core/shell nanoparticles have been synthesized and characterized.•The core/shell structures were employed as catalysts for reduction of Congo red in water.•The reduction process is rapid and dependent on the operating reaction conditions.•The Pd@Ag core/shell catalyst is the more catalytically active than Pt@Ag.