以電化學法在立體微米銅微柱表面合成氧化鋅奈米柱、管結構與氣體感測之特性研究

Gas Sensing Properties of ZnO Nanorods and Nanotubes Synthesized on 3D Cu Micro-column by Electrochemical Method

本研究以電化學之方式，在銅微柱表面沉積氧化鋅奈米柱，再經由濕式蝕刻之方式，將氧化鋅奈米柱蝕刻成奈米管結構，並藉由掃描式電子顯微鏡（SEM）觀察經電化學法沉積後之奈米柱與經濕式蝕刻後而形成之奈米管形貌，再由X光結晶繞射儀（XRD）分析其結構差異與X光光電子能譜儀（XPS）分析氧化鋅之化學能態與鍵結能，並以批覆在銅微柱表面之氧化鋅奈米柱及奈米管來進行氣體偵測實驗。氣體感測實驗中，在酒精及一氧化碳的氣氛下，氧化鋅奈米管較氧化鋅奈米柱有較高靈敏度，由於氧化鋅奈米管較奈米柱有較高的比表面積，特殊的中空結構提供較多的位置吸附氣體分子並增加偵測靈敏度。在偵測溫度於150℃~ 300℃，氧化鋅之靈敏度呈上升之趨勢，超過300℃、在400℃以下溫度量測則靈敏度下降；在相同濃度之氣氛環境，氧化鋅奈米管對酒精混合氣體有較高的氣體偵測靈敏度。

In this study, ZnO nanorods on Cu micro-column were synthesized by electrochemical method, then ZnO nanorods were etched to tubular structure by wet etching technique. ZnO nanorods and nanotubes were formed by using electrochemical method and were deposited on electrodes of the copper micro-columns. The morphology and crystal structure of ZnO nanorods and nanotubes were studied by scanning electron microscopy (SEM) and X-ray diffraction (XRD), the chemical state and binding energy were determined by X-ray photoelectron spectroscopy (XPS), respectively. Then these ZnO nanorods and nanotubes were used for gas sensing. In gas sensing test, the ZnO nanotubes exhibited higher sensing response than ZnO nanorods in both carbon monoxide mixture gases (CO and air) and ethanol mixture gases (ethanol and air), this was due to the ZnO nanotubes have the higher specific surface area than ZnO nanorods, and the special hollow structures of ZnO nanorod provides more active sites for gas molecules to get adsorbed into the surface and promote the sensitivity. The sensitivity showed the rising trend with the increasing temperature from 150 ℃ ~ 300 ℃; but, over 300 ℃ and below 400 ℃, the sensitivity decreased. In the same concentration CO mixture gases (CO and air) and ethanol mixture gases (ethanol and air), the ZnO nanotube showed higher sensing response for ethanol mixing gases.