Silver-based nanocrystals have excellent catalytic performance in various reactions, such as the reduction of 4-nitrophenol. The catalytic performance of nanocrystals varies with several parameters, including nanocrystal morphology, composition, and plasmon-induced hot electrons around nanocrystals. Here, highly heterogeneous nanocrystals (Au-Ag and Ag2S-Ag nanocrystals) fabricated on polymer films via a seed-mediated method are used as catalysts for the reduction of 4-nitrophenol, and the effect of the morphology and composition of nanocrystals on the catalytic performance is investigated. These nanocrystals on polymer films exhibit higher reusability (low catalyst loss) in catalytic applications compared to catalysts dispersed freely in the reaction solution. The excellent catalyst performance of these heterogeneous nanocrystals is attributed to their high surface area/volume ratio (flower-like nanocrystals) and strong synergistic effect (cage-like nanocrystals). These nanocrystals with special morphologies and composites showed higher catalytic performance (higher reactivity at lower catalyst contents) than silver-based nanocrystals reported in the literature. Due to the excellent plasmonic properties of Ag nanocrystals, the catalytic performance of these nanocrystals can be further enhanced by generating hot electrons around the nanocrystals under irradiation. These results demonstrated that by carefully controlling the morphology and composition of nanocrystals, it is possible to design and fabricate excellent catalysts for various reactions.
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