Electronic structure and surface structure of Cu2S nanorods from polarization dependent X-ray absorption spectroscopy

Highly aligned Cu2S nanorods have been studied by polarization dependent X-ray absorption spectroscopy. In contrast to bulk Cu2S, strong s, p, and d hybridization is found in the nanorods. The polarization dependence shows a predominant dz2 character of Cu 3d states. Ab initio multiple-scattering calculations confirm the strong hybridization, and reveal that Cu2S nanorods are grown along the z-axis of chalcocite structure with Cu7 and Cu10 sites being the main building blocks. The hybridized absorption peak in the nanorods is shifted towards lower energies for smaller diameter of nanorods, which is attributed to surface reconstruction due to strong Cu-Cu interactions on the Cu-rich surface of the nanorods.