Janus-like Metallic Nanocrystals with Tunable Composition and Morphology Developed to Optimize their Catalytic and Photocatalytic Performance in the Reduction of 4-NP and Organic Dyes.

Highly heterogeneous Janus-type nanocrystals with tunable morphology and composition can be obtained through a "two-step continuous seed-mediated" method. These Janus-like nanocrystals, composed of active materials (Au and Pt) and plasmonic materials (Ag and Au), exhibit significantly higher catalytic performance in 4-NP and organic dye reduction reactions, approximately 1.5 to 5 times higher, compared to bimetallic nanocrystals with one-half of the Janus-like nanocrystal structure (prepared using conventional seed-mediated methods). This can be attributed to the greater number of active sites (surface area/volume ratio) and higher activity sites (synergistic effect) of the Janus-like nanocrystals. Furthermore, Janus-like nanocrystals, composed of superior plasmonic materials, can further enhance their catalytic performance by converting photon energy into chemical energy under irradiation with light of a specific wavelength (generating plasmon-induced hot electrons around the nanocrystals). Compared with the catalytic and photocatalytic performance of bimetallic nanocrystals Au-Ag and Pt-Ag reported in the literature, these Janus-like nanocrystals, with their highly heterogeneous morphology and composition, can degrade 4 to 102 times more 4-NP molecules per unit weight of nanocrystals as catalysts or photocatalysts. These results demonstrate that by adjusting the morphology and composition of nanocrystals, specific chemical reactions can be accelerated, making the design of multifunctional heterogeneous nanocrystals through a "multistep continuous seed-mediated" method valuable.