Lattice and ligand engineering for hierarchical heterogeneous nanocrystals

Precise control over the morphology, structure, and composition of nanocrystals is essential for designing advanced functional materials. Herein, we establish a general paradigm for the programmable synthesis of hierarchical heteronanocrystals by synergistically integrating ligand-mediated site-selective epitaxy with lattice mismatch engineering. We demonstrate that the curvature-dependent distribution of surface ligands on hexagonal nanorods enables site-selective epitaxial growth, leading to the formation of secondary satellite nanocrystals at predetermined positions. Strong ligand binding is identified as a key factor governing this ordered epitaxial process. By varying the composition of the epitaxial material across 8 kinds of rare-earth ions (from Yttrium to Cerium), we find the lattice mismatch between substrate and the epitaxial deposit dictates three distinct growth regimes: a mismatch below 2.0% results in uniform coating, a mismatch between 2.0% and 5.1% leads to island formation, and a mismatch exceeding 7.1% induces homogeneous nucleation. Harnessing these principles, we implement a programmable epitaxial strategy to precisely integrate 4 distinct elements onto a heterogeneous nanorod, constructing a complex 3D hierarchical architecture with 14 segments within a 160 nm × 50 nm framework. This work opens avenues for the on-demand fabrication of sophisticated nanostructures.