Synthesis of Convex Hexoctahedral Palladium@Gold Core–Shell Nanocrystals with {431} High-Index Facets with Remarkable Electrochemiluminescence Activities

Convex hexoctahedral nanocrystals have been synthesized through fast growth kinetics and the use of cetylpyridinium chloride as a capping agent. Monodisperse convex hexoctahedral Pd@Au core-shell nanocrystals with {431} high-index facets are obtained at high reaction rates by using high concentrations of ascorbic acid in the presence of cetylpyridinium chloride. In contrast, octahedral nanocrystals with {111} low-index facets and their {100}-truncated counterparts are formed at low ascorbic acid concentrations. The substitute of cetylpyridinium chloride with cetyltrimethylammonium chloride leads to the generation of concave trisoctahedral Pd@Au core-shell nanocrystals with {331} high-index facets, indicating that cetylpyridinium plays an important role in the formation of convex hexoctahedral nanocrystals. The as-prepared convex hexoctahedral Pd@Au core-shell nanocrystals exhibit remarkable catalytic performances toward electrochemiluminescence compared with truncated octahedral and concave trisoctahedral Pd@Au core-shell nanocrystals.