Tailoring the sensing properties of microwave-assisted grown ZnO nanorods: Effect of irradiation time on luminescence and magnetic behaviour

This paper reports on highly crystalline ZnO nanorods with different lengths and widths, grown using a microwave-assisted hydrothermal method at different irradiation times. The BET (Brunauer, Emmet, Teller) surface area increased while the lengths and widths of the ZnO nanorods were reduced with increasing irradiation time. The combination of photoluminescence (PL) and electron paramagnetic resonance (EPR) analyses elucidated that the defect-related properties affect the sensing response of the ZnO nanostructures. A broad visible emission band related to Zn-i and V-O surface defects on the surfaces of ZnO nanorods was observed. The EPR studies revealed the ferromagnetic signal with a g-value of >2.0 for all ZnO nanostructures induced by Zn-i and V-O surface defects. Gas sensors based on these ZnO nanorods exhibited a high sensing response to CO at 350 degrees C. Thus, our findings showed that the high response originates from surface defects (Zni and VO) formed at the surfaces of ZnO nanorods. (C) 2015 Elsevier B.V. All rights reserved.