Seed-Particle-Independent In-situ Synthesis of Surface-Templated Shape-Selected Palladium Nanoparticle Arrays

Surface-templated metal nanoparticle synthesis combines the best of lithography-based nanofabrication on surfaces and colloidal nanocrystal growth in solution, and it is well accepted that the final structure and crystallinity of nanoparticles grown using the seed-mediated method is strongly linked to the structure, morphology and crystallinity of the initial seed. Here, we challenge this paradigm by introducing regioselective particle growth enabled by a sacrificial polymer layer used to tailor the fraction of seed particle surface exposed to a growth solution and thereby defining the growth mode of the particle. Mechanistically, this confines metal deposition to a small, selected region of the seed surface and decouples the growth mode from size, morphology, crystallinity and composition of the seed. As we show on the example of Pd, this enables the in situ surface-templated growth of regular arrays of polycrystalline nanoflowers, spiky nanostars and single crystalline nanocubes with over 90% yield, using identical growth conditions and nanolithography-fabricated regular arrays of morphologically poorly defined polycrystalline seeds, as well as crafting heterodimeric single crystalline Pd nanocubes at the tip of a large polycrystalline Au nanocone. This widens the practical applicability of surface-templated nanofabrication with rationally arranged metal particles with well-defined morphologies, crystallinity and composition.