Peptide-Directed Nanomaterials to Elucidate Compositional Effects in Bimetallic Nanoparticle Catalysts

Multimetallic nanoparticle catalysts present exciting opportunities to achieve sustainable chemical transformations based on their unique structure that can lead to enhanced reactivity, especially when a blend of functional metal atoms is incorporated. The fundamental science regarding the interaction between the metal types and the role of the surface ligands is developing, especially as the number of constituent atom types increases. To investigate these effects, a set of three different bimetallic nanoparticles were prepared (PdAu, AuAg, and PdAg) using the same peptide capping agent (the AuBP1 peptide). Simplified bimetallic materials were probed with a similar interfacial ligand to explore the effect of switching metal composition on catalytic activity, as well as the breadth of compositions that could be prepared using the same peptide ligand. Characterization of the stable structures indicated that bimetallic alloy nanocatalysts were generated with sizes of less than 5 nm in diameter. Catalytic analysis for the reduction of 4-nitrophenol revealed enhanced reactivity for nanoparticles prepared with PdAu and AuAg at metal/metal ratios of 3:2 and 4:1, respectively. These results demonstrate key structural and compositional effects in the materials, which could be used to design different particles of increased complexity for further reactivity enhancement.