Overcoming Template Constraints: Anion Exchange in Zn Chalcogenide Nanoplatelets

Achieving nondestructive anion exchange in semiconductor nanostructures without templates remains a significant challenge, primarily due to slow diffusion kinetics and structural instability. Here, guided by density functional theory (DFT), we report an efficient template-free anion exchange in Zn-based nanoplatelets (NPLs). Our study reveals that the Zn-terminated (0001) facet possesses low surface energy and strong affinity for sulfide ions, facilitating their interstitial diffusion along the [0001] direction. The exchange follows first-order kinetics with k_obs = 0.0336 min^-1. Ligand engineering further demonstrates that short-chain amines promote [0001]-oriented epitaxial growth, while long-chain amines inhibit exchange. Additionally, we identify two distinct transformation pathways driven by ionic radius mismatch: a facet-selective direct substitution for small ionic radius mismatches, and a cluster-mediated pathway for large mismatches. These findings provide a framework framework for template-free anion exchange and provide suggest strategies for designing high-performance functional nanomaterials.