Effect of the chemical nature of the anions on the electrodeposition of ZnO nanowire arrays

An investigation of the electrodeposition of ZnO nanowire arrays from the reduction of dissolved molecular oxygen in solutions containing different anions (Cl-, SO42-, and CH3COO-) is reported. A significant variation of the diameter (65-110 nm) and length (1.0-3.4 mu m) of the nanowires was obtained by changing only the nature of the anions in the solution. Nanowires exhibiting the lowest and highest aspect ratios were obtained in chloride and acetate solutions, respectively. The diffusion of Zn2+ to the cathode and the OH- generation rate were analyzed by cyclic voltammetry. The difference in adsorption behaviors of the different anions on the ZnO surface is proposed as one of the main reasons for the observed differences in the OH- production rate. The ratio between the OH- generation rate and the Zn2+ diffusion to the cathode is proposed as a major parameter in the electrodeposition of ZnO nanowires. Obtained samples were analyzed by X-ray diffraction, and no spurious phases were observed. Thus, changing the chemical nature of the anions in solution allows for the dimensions and the deposition rate of electrodeposited ZnO nanowire arrays to be controlled.