本研究利用陽極氧化法製備二氧化鈦奈米管元件以作為電阻式氣體感測器。首先，將鈦金屬濺鍍於石英玻璃上，再在NH4F-H2O-EG電解液中進行陽極氧化以獲得二氧化鈦奈米管陣列(TiO2 NTA)，然後沉積金屬電極以製成TiO2 NTA/quartz元件，並進行氫(H2)、氨氣(NH3)和二氧化氮(NO2)感測實驗。研究中旨在探討金屬電極對氣體感測特性之影響，並由氣體感測結果推導其感測機制。
實驗結果顯示，鉑、金和鈀三種金屬電極元件對氫氣之感測能力遠較氨、二氧化氮為佳。比較此三種元件發現，對於氫氣之感測靈敏度依序為鉑、鈀、金電極元件。由此可知，鉑及鈀對氫之溢流效應可提升元件之感測能力。在373K下，鉑電極元件之靈敏度可達到2.85×104 (1% H2/N2)；即使在100 ppb H2/N2之低濃度下，靈敏度仍可達到1個數量級。由暫態結果得知，隨著溫度及濃度之增加，其響應速率也隨之增加，在473K、1%H2/N2下，響應時間僅需15秒。
當氫氣感測實驗於空氣氣氛下進行時，由於氫氣與表面吸附之O2作用使TiO2奈米管表面之氧離子被移除，而空氣中之氧氣會回填至TiO2表面氧空缺，又形成O2。因此，響應之電流值可迅速達到穩態。但與氮氣氣氛相比可知，元件於空氣氣氛下之氫氣感測靈敏度不高(373K, 1% H2/air, S=304.9)，且此兩者相差約2個數量級。
另外，由NH3及NO2之感測結果顯示，鉑電極對NH3之感測能力較佳，靈敏度為27(373K, 200ppm NH3/N2)；而金電極則對NO2具較高之感測能力，靈敏度可達到6.4×103(373K,100ppm NO2/N2)。但兩種氣體在感測後無法回復至原始基線電流值，推測NH3、NO2可能會與二氧化鈦作用而產生毒化現象。

In this study, the TiO2 nanotube arrays (NTAs)/quartz fabricated by anodization were used as resistive-type gas sensors. Firstly, a thin Ti film was deposited on the quartz substrate by RF sputtering. Subsequently, the sample was anodized in an NH4F-H2O-EG electrolyte to form highly ordered TiO2 NTAs. Then, a metal electrode was deposited onto the TiO2 surface to obtain TiO2 NTA/quartz device. Furthermore, the sensing characteristics of the studied devices were investigated on H2, NH3 and NO2 gases, respectively. The effects of metal electrode on gas sensing performance were emphasized. In addition, the gas sensing mechanism was also deduced.
From the experimental results, it indicated that three sensor devices with metal electrodes of Pt, Au and Pd all showed superior sensing ability to H2 more than NH3 and NO2. Comparing these three kinds of gas sensors, it was found that the hydrogen sensitivity was decreased in the sequence as Pt > Pd > Au. The sensitivity of TiO2 NTA/quartz device exposed to 1% H2/N2 at 373K could reach up to 2.85×104. Even at extremely low hydrogen concentration, e.g., 100 ppb H2/N2, the sensitivity still approached to about 1 order. From results of I-t transient responses, the response rate of the Pt/TiO2 NTA/quartz was increased with increasing either temperature or hydrogen concentration. For the hydrogen sensing at 473K under 1% H2/N2 ambience, the response time was only 15s.
When the hydrogen sensing experiments performed in the air ambience, the adsorbed oxygen (O2) was removed from the TiO2 surface by the reaction with hydrogen, and then the oxygen vacancies would be backfill by oxygen from air ambience and formed O2 again. Consequently, the sensing current could reach to the steady-state value rapidly. As compared with the sensitivity in N2 ambience, it showed that the hydrogen sensitivity in air was relatively low (373K, 1% H2/air, S=304.9), which deviated even reaching to about 2 order.

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