Synthesis of highly heterogeneous Pt-Ag nanocrystals for catalytic and photocatalytic applications

Metal nanocrystals, such as Ag and Pt nanocrystals, are widely used as catalysts for various chemical reactions due to their high activity. The activity of metal nanocrystals can be further enhanced by forming multiple composite nanocrystal (synergistic effect) or increasing the heterogeneity of the nanocrystal morphology (high surface area to volume ratio). Here, we fabricated Pt-Ag nanocrystals with highly heterogeneous morphologies, mushroom-like/flower-like/half-cage-like, through a "seed-mediated" synthesis method in a hydrophobic layer, which can be used to suppress the nanocrystals aggregation issue for catalytic applications. When these Pt-Ag nanocrystals are used as 4-nitrophenol reduction catalysts, the catalytic performance of these nanocrystals largely depends on their composition and morphology. Compared with mushroom-like Pt-Ag nanocrystals, flower-like and half-cage-like Pt-Ag nanocrystals exhibit higher catalytic activity, which is attributed their morphological effect (high surface area to volume ratio) and composition effect (synergistic effect), respectively. And compared with other Pt/Ag/Pt-Ag nanocrystals as 4-nitrophenol (4-NP) reduction catalysts reported in the literature, these highly heterogeneous Pt-Ag nanocrystals on the hydrophobic layer showed significant catalytic performance enhancement effects, which can be attributed to their composite and morphological effects and suppresses nanocrystal aggregation. These Pt-Ag nanocrystals can also be used as photocatalysts under visible light irradiation to further enhance their catalytic performance, due to the excellent plasmonic response of Ag nanocrystals under visible light.