Bismuth-catalyzed synthesis of ZnO nanowires and their photoluminescence properties

By means of heating a mixture of Zn and Bi powders, we have successfully prepared ZnO nanowires. Since the produced nanowires correspond to the pure hexagonal ZnO phase with no catalytic nanoparticles being observed at the tips, the growth is dominated by the base-growth mechanism, in which Bi species at the bottom of the nanowires played a catalytic role. Photoluminescence (PL) analysis of indicated that the integrated intensity ratio of the 2.5 eV-band to the UV band increased with increased growth temperature. An increase of the Bi2O3 phase itself, Bi2O3 phase-induced oxygen vacancies, and an increase of oxygen vacancies in ZnO with increasing growth temperature were responsible for the intensification and the appearance of the 2.5 eV-band.