Synthesis of TiO2 nanorods decorated with NiO nanoparticles and their acetone sensing properties

TiO2 nanorods decorated with NiO nanoparticles were synthesized by a facile hydrothermal process and their acetone gas sensing properties were examined. The diameters and lengths of the TiO2 nanorods ranged from 50 to 500 nm and from 1 to 4 μm, respectively, whereas the NiO nanoparticles had a hexagonal plate-like morphology with an average diameter of ~150 nm and an average thickness of ~20 nm. The NiO-decorated TiO2 nanorod sensor showed stronger response to acetone gas than its pristine TiO2 nanorod counterpart. The pristine and NiO-decorated TiO2 nanorod sensors exhibited responses of ~5.76 and ~9.33, respectively, to 200 ppm acetone at 400 °C. The decorated nanorod sensor also showed short sensing time than the latter. Both sensors showed the strongest response to acetone gas at 400 °C. The mechanism and origin of the enhanced acetone gas sensing performance of the NiO-decorated TiO2 nanorod sensor compared to its pristine TiO2 nanorod counterpart were discussed in detail. The enhanced sensing performance of the NiO-decorated TiO2 nanorod sensor is mainly due to the modulation of the potential barrier height at the TiO2-NiO interface, high catalytic activity of NiO and creation of active adsorption sites by incorporation of NiO.