Charge transfer in nanocrystalline- AuZnO nanorods investigated by x-ray spectroscopy and scanning photoelectron microscopy

O K - and Zn and Au L3 -edge x-ray absorption near-edge structure (XANES), x-ray emission spectroscopy (XES), and scanning photoelectron microscopy (SPEM) are performed to investigate the electronic structure of ZnO nanorods with nanocrystalline (nc) -Au particles grown on the surfaces. The XANES spectra of nc-AuZnO nanorods reveal the decrease of the number of both O 2p and Zn 4s3d unoccupied states with the increase of the nc-Au particle size. The number of Au 6s5d unoccupied states increases when the size of nc-Au particle decreases, indicating that the deposition of nc-Au particles on the surface of ZnO nanorods promotes charge transfer from the ZnO nanorods to nc-Au particles. Excitation energy dependent XES and SPEM spectra show that the number of electrons in the valence band of O 2p-Zn 4sp hybridized states decreases as the nc-Au particle size increases, revealing that more electrons are excited from the valence band to the conduction band of ZnO nanorods and the storage of electrons in nc-Au particles.