Intrinsically Chiral Au–Cu2O Janus Nanostructures: Construction and Chiroptical Properties

Abstract Chiral metal–semiconductor Janus nanostructures enable the integration of plasmonic chirality and asymmetric heterointerfaces, yet precisely constructing such architectures while retaining plasmonic chiral features remains challenging. Herein, chiral Au–Cu2O Janus nanostructures are fabricated using intrinsically chiral Au rhombic dodecahedra as a substrate through a site-selective growth method. The Cu2O growth transitions from conformal coating to asymmetric, one-sided Janus growth, yielding hybrids with tunable spatial asymmetry. Optical and g-factor spectra exhibit distinct evolutions driven by varied dielectric environments and plasmonic coupling, showing geometry-dependent chiroptical activities. Multipolar analysis further reveals that the core–shell-to-Janus transformation redistributes dipole/quadrupole contributions, switching chiroptical modulation from global reconstruction to localized interfacial regulation. This work not only demonstrates the correlation between structure and chiroptical activities but also guides the rational design of chiral heterostructures for sensing and catalysis.