文摘
ZnO nanorods/TiOb>2b> nanoparticles composites were synthesized and the effects of TiOb>2b> concentrations on the NOb>2b> sensing properties were studied in detail. The as-prepared composites were characterized by XRD, SEM, TEM, PL, I-V and gas sensing measurements. The gas sensing results demonstrated that all the sensors based on ZnO/TiOb>2b> nanocomposites exhibited much higher response than that of sensors based on pure ZnO nanorods. At the optimum operating temperature of 180 °C, the response values of the sensors based on ZnO/TiOb>2b> nanocomposites decorated with TiOb>2b> concentrations of 0, 3, 5, 8 and 10 wt% were 50, 140, 310, 350 and 258, respectively. The PL and I-V results indicated that the increased charge transfer between the ZnO nanorods mediated by TiOb>2b> nanoparticles enhanced the conductivity of the ZnO/TiOb>2b> nanocomposites. The gas sensing mechanism was also carefully analyzed. The attachment of TiOb>2b> nanoparticles onto ZnO nanorods induced more active sites for the adsorption of oxygen molecules (O2) and O2 which can be more easily adsorbed on the surface of ZnO nanorods. Furthermore, the conduction channel of ZnO/TiOb>2b> was much narrower as a result of the formation of heterojunction which may further contribute to the enhanced NOb>2b> sensing properties.