Hierarchical graphene quantum dot–copper nanocluster superstructures: synergistic assembly for optical limiting applications

Abstract

This work unveils for the first time self-assembled glutathione-stabilized copper nanoclusters and their synergistic assembly with the covalent linking of N,S-doped graphene quantum dots for optical limiting applications. The covalent hybridization induces a morphological evolution in the hybrid material leading to unique photophysical properties. Comprehensive physicochemical characterization confirmed the preservation of cluster integrity and the atomically precise nature of the building blocks. High-resolution transmission electron microscopy revealed a distinct hexagonal morphology that we attributed to the self-assembly of the individual cluster units. The designed hybrid also shows improved nonlinear optical properties, including the two-photon absorption coefficient and excellent optical limiting performance. UV-Vis, FTIR, XPS, TEM, photoluminescence spectroscopy, and mass spectroscopy were used to elucidate the structure–property relationship of the hybrid.