(452b) Enhancing Catalytic Activity of Au Alloy Nanoparticles Stabilized Exclusively with Borohydride Ions

Metal nanoparticles play a prominent role in catalysis due to their ability to activate molecules for chemical reactions. However, traditional synthesis methods of metallic nanoparticles involve ligands, surfactants, or supports which can block catalytic sites on the surface. Here, we report the synthesis of gold-ruthenium and gold-cobalt nanoparticles in an aqueous solution using sodium borohydride having a dual role as the reducing agent and as a stabilizing agent. Sodium borohydride can easily make way for reactants to bind to the catalyst surface. Alloying gold with another metal has been shown to enhance catalytic activity, selectivity, and structure when compared to monometallic gold nanoparticles. The nanoparticles are first characterized using a UV-vis spectrophotometer. The UV-vis spectra of the bimetallic nanoparticles show a blue shift in the surface plasmon resonance band compared to the monometallic gold nanoparticles, indicating the formation of metal alloys. The AuNP nanoparticles have a characteristic peak at 522 nm. The AuRu and AuCo show a shift in the SPR band with peaks at 509 nm and 520 nm, respectively. Particle sizes are estimated to be approximately 4 nm based on TEM measurements. These nanoparticles show an enhanced catalytic activity for the electron transfer reaction between sodium thiosulfate and potassium hexacyanoferrate. Gold-ruthenium nanoparticles significantly increase the first-order reaction rate constant from 0.0013 min^-1 to 0.005 min^-1 when compared to monometallic gold. Similarly, gold-cobalt nanoparticles exhibit increased catalytic activity with a rate constant of 0.003 min^-1. Furthermore, these catalysts effectively catalyze the hydrogen peroxide decomposition reaction, with activities of 0.005 min^-1 and 0.003 min^-1 for gold-ruthenium and gold-cobalt, respectively. These findings demonstrate the successful synthesis of stable bimetallic nanoparticles without strongly binding ligands and their catalytic efficacy.