Facet-dependent electrochemiluminescence spectrum of nanostructured ZnO

A facet-dependent electrochemiluminescence (ECL) behavior was found for nanostructured ZnO with different dominant exposing planes. The ECL spectrum of nanostructured ZnO was recorded by the emission scan mode with a fluorescence spectrometer and applied to investigate the difference of surface state for different crystal planes. Electronic structure calculations based on density functional theory were used to study the effect of crystal plane on the band structure and density of states. It revealed that the ECL emission was originated primarily from the recombination of electrons from Zn 4s and the hole from O 2p, which could be utilized to study the physical and chemical properties of surface structures of as-prepared nanostructured ZnO. A physical model was suggested to elucidate the differences of ECL spectra. A concept was proposed that the energy released as photons during ECL process of nanocrystalline semiconductor materials will be correlated with the energy level of active sites located at different crystal planes.