Theoretical Insights Into Templated Growth Mechanism of Au Nanoclusters on Moiré Superlattices

Moiré superlattices generated by 2D materials, such as graphene and hexagonal boron nitride (hBN), on metal substrates are demonstrated to be outstanding templates for uniformly growing a range of metal nanoclusters. However, the growth of widely used Au nanoclusters (AuNCs) on the two templates is completely different. Herein, the distinct growth modes of AuNCs on both templates are elucidated using first-principles calculations. The investigation reveals that, on hBN moiré superlattices, template-induced sp³-hybridization of B atoms exhibits strong coupling with Au atoms at the template center, and gradually weakens as the cluster expands, thereby facilitating the templated growth of AuNCs. Furthermore, the strong coupling can be attributed to the empty B-p_z orbitals accepting electrons from Au atoms, simultaneously fulfilling the stability requirement of 10 electrons of the Au-d orbitals and the octet rule for the B atoms. In contrast, on graphene moiré superlattices, the C atom with one p_z electron cannot form a strong bond with Au, as this would exceed Au's 10 d-electron limit, resulting in non-templated growth. This work will deepen the understanding of cluster-template interactions and provide guidance for the templated growth of more metal nanoclusters.