This study compared the responses of Pd-functionalized and pristine titanate (TiO
2) nanotube arrays to ethanol with those to acetone to determine the effects of functionalization of TiO
2 nanotubes with Pd nanoparticles on the sensitivity and selectivity. The responses of pristine
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This study compared the responses of Pd-functionalized and pristine titanate (TiO
2) nanotube arrays to ethanol with those to acetone to determine the effects of functionalization of TiO
2 nanotubes with Pd nanoparticles on the sensitivity and selectivity. The responses of pristine and Pd-functionalized TiO
2 nanotube arrays to ethanol gas at 200 °C were ~2877% and ~21,253%, respectively. On the other hand, the responses of pristine and Pd-functionalized TiO
2 nanotube arrays to acetone gas at 250 °C were ~1636% and 8746% respectively. In the case of ethanol sensing, the response and recovery times of Pd-functionalized TiO
2 nanotubes (10.2 and 7.1 s) were obviously shorter than those of pristine TiO
2 nanotubes (14.3 and 8.8 s), respectively. In contrast, in the case of acetone sensing the response and recovery times of Pd-functionalized TiO
2 nanotubes (42.5 and 19.7 s) were almost the same as those of pristine TiO
2 nanotubes (47.2 and 17.9 s). TiO
2 nanotube arrays showed the strongest response to ethanol and Pd functionalization was the most effective in improving the response of TiO
2 nanotubes to ethanol among six different types of gases: ethanol, acetone, CO, H
2, NH
3 and NO
2. The origin of the superior sensing properties of Pd-functionalized TiO
2 nanotubes toward ethanol to acetone is also discussed.
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