Design of Nanoscaled Surface Morphology of TiO(2)–Ag(2)O Composite Nanorods through Sputtering Decoration Process and Their Low-Concentration NO(2) Gas-Sensing Behaviors

TiO(2)–Ag(2)O composite nanorods with various Ag(2)O configurations were synthesized by a two-step process, in which the core TiO(2) nanorods were prepared by the hydrothermal method and subsequently the Ag(2)O crystals were deposited by sputtering deposition. Two types of the TiO(2)–Ag(2)O composite nanorods were fabricated; specifically, discrete Ag(2)O particle-decorated TiO(2) composite nanorods and layered Ag(2)O-encapsulated TiO(2) core–shell nanorods were designed by controlling the sputtering duration of the Ag(2)O. The structural analysis revealed that the TiO(2)–Ag(2)O composite nanorods have high crystallinity. Moreover, precise control of the Ag(2)O sputtering duration realized the dispersive decoration of the Ag(2)O particles on the surfaces of the TiO(2) nanorods. By contrast, aggregation of the massive Ag(2)O particles occurred with a prolonged Ag(2)O sputtering duration; this engendered a layered coverage of the Ag(2)O clusters on the surfaces of the TiO(2) nanorods. The TiO(2)–Ag(2)O composite nanorods with different Ag(2)O coverage morphologies were used as chemoresistive sensors for the detection of trace amounts of NO(2) gas. The NO(2) gas-sensing performances of various TiO(2)–Ag(2)O composite nanorods were compared with that of pristine TiO(2) nanorods. The underlying mechanisms for the enhanced sensing performance were also discussed.