Role of Annealing Temperature on the Formation of Aligned Zinc Oxide Nanorod Arrays for Efficient Photocatalysts and Photodetectors

Aligned ZnO nanorod arrays with well-controlled surface roughness were synthesized using a seed-assisted hydrothermal method, supported by investigations of the impact of annealing treatments on seed formation. Results indicated that the diameters, lengths, and axial alignments of the formed ZnO nanorod arrays essentially depended on annealing temperatures, and that the transition from random orientation toward aligned morphology could be effectively adjusted through thermal treatment of the seed layers. Both photocatalytic and photodetection properties in relation to annealing treatments were studied. The aligned ZnO nanorods with rough surfaces prepared at 300 degrees C annealing possessed superior photodegradation efficiency and the involved kinetics was satisfactorily interpretable on the basis of a second-order kinetic model. Upon integration with a patterned electrode, these ZnO-nanorod-based devices emerged as efficient UV photodetectors showing both drastic increments and adequate wavelength selectivity for generated photocurrents. These results could be potentially used for practical and cost-effective photochemical and photodetecting applications.