Large-scale hexagonal Znic oxide (ZnO) with a surface-roughened nanostructure on Zn-electrodes is synthesized via a self-electrochemical transformation in sodium chloride gel without employing an annealing process. By tuning the discharged current down to 6.9 mA during self-electrochemical oxidation, a large amount of Zn(OH)(2) composites can be effectively transformed into [Zn(OH)(4)](2-) to cause isotropic ZnO growth, which ascribes to the spontaneous electrochemical oxidation induced stable electro-migration with minimized Gibbs free energy. With decreasing discharged current to improve the crystallinity, the wurtzite-type hexagonal ZnO crystal with (101) preferred orientation and a lattice spacing of 2.46 angstrom exhibit an optimized optical responsivity of 350 mA/W under illumination at 35 mW/cm(2). Nevertheless, increasing the discharged current up to 49.4 mA inevitably enhances the oxygen-defect related photoluminescence by 1 order of magnitude and red shifts the wavelength to 552 nm. Our results show that the significantly decreased oxygen-defect radiation and oppositely improved bandgap UV emissions are controllable through a reduction of the discharged current in order to decelerate the electrochemical oxidation as regards crystallinity optimization. (C) 2011 The Electrochemical Society. [DOI: 10.1149/1.3601875] All rights reserved.