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.