本研究利用水熱合成法成長氧化石墨烯/氧化鋅(graphene oxide/ZnO)奈米柱於具有粗糙化之晶種層上，並經熱處理使其變成還原型-氧化石墨烯/氧化鋅奈米柱，並將其應用於NO2氣體感測器作為氣體感測層；其中探討不同濃度之氧化石墨烯對於成長氧化鋅奈米柱的影響及對目標氣體響應特性之改變。由於石墨烯為p型半導體，而氧化鋅奈米柱為n型半導體，故藉由水熱合成法於成長氧化鋅奈米柱時，加入氧化石墨烯能與氧化鋅奈米柱之表面形成p-n異質接面，進而提升對目標氣體的響應度，而石墨烯本身具有高比表面積和優良的電特性，因此使元件能在更低操作溫度下即有最佳響應特性，因此摻雜氧化石墨烯能使先前氧化鋅奈米柱氣體感測器特性更佳提升。
本研究利用X射線光電子能譜儀(XPS)確認氧化石墨烯薄膜之含氧官能基經退火後是否有減少其在薄膜中的比例，進而證實氧化石墨烯薄膜還原成還原型-氧化石墨烯薄膜；並利用拉曼(Raman)光譜分析儀探討氧化石墨烯薄膜經氬氣退火和氫氣退火其薄膜缺陷態之差異。
本研究以水熱合成法成長氧化石墨烯/氧化鋅奈米柱，使用前驅物硝酸鋅六水化合物及六亞甲基四胺濃度各為20 mM、成長時間為3小時與粗糙化的晶種層厚度及周期分別為40 nm及2 μm，其中改變氧化石墨烯的濃度0、5、10、15和20 mg/ml (DI water)，最後利用氫氣400 oC退火4分鐘對所製作的奈米柱進行熱退火處理，使氧化石墨烯轉變成還原型-氧化石墨烯，並且氫氣處理可以增加氧化鋅奈米柱之氧空缺。以掃描式電子顯微鏡(SEM)觀察利用不同氧化石墨烯濃度所製備之還原型-氧化石墨烯/氧化鋅奈米柱的表面形貌，並利用穿透式電子顯微鏡(TEM)和能量色散光譜儀(EDS)來觀察還原型-氧化石墨烯/氧化鋅奈米柱的剖面結構及氧化石墨烯所在的位置。將所製備的不同氧化石墨烯濃度所製備之還原型-氧化石墨烯/氧化鋅奈米柱應用於NO2氣體感測器作為氣體感測層，其中分析探討不同氧化石墨烯濃度對氣體感測器特性之影響。由實驗結果顯示，不同氧化石墨烯濃度0、5、10、15和20 mg/ml所製備之還原型-氧化石墨烯/氧化鋅奈米柱氣體感測器的響應度分別為305.4 %、430.2 %、792.6 %、525.8 %和320.5 %，最佳操作溫度分別為150 oC、150 oC、135 oC、135 oC和135 oC。還原型-氧化石墨烯/氧化鋅奈米柱氣體感測器的特性皆優於無氧化石墨烯摻雜之氧化鋅奈米柱氣體感測器；當摻雜氧化石墨烯濃度為10 mg/ml，NO2氣體感測器有最高響應度792.6 %，最低操作溫度135 oC，可偵測0.5 ppm微量二氧化氮及有良好的選擇性。

In this study, graphene oxide/ZnO nanorods were synthesis by simple hydrothermal method. To optimal the graphene oxide/ZnO nanorods gas sensing properties, the graphene oxide/ZnO nanorods was annealing to be reduced graphene oxide/ZnO nanorords. In the process, also modulated graphene oxide doping concentration, when the concentration of graphene oxide was 10 mg/ml, that had the best responsivity:792.6 % at the operating temperature 135 oC. By doping the graphene oxide, which can form the p-n heterojunction and increase the nanorods conductivity further to improve the responsivity to 100 ppm NO2 and decrease the gas sensor operating temperature. In this research, the reduced graphene oxide defect and chemical bonding were verified by Raman spectra and X-ray photoelectron spectroscopy (XPS). The morphology of reduced graphene oxide at different doping concentration were analyzed by scanning electron microscope (SEM) and high-resolution transmission electron microscope (HR-TEM), also used the two-dimensional element image analysis (elemental mapping) function in the energy dispersive spectrometer (EDS) to verify that reduced graphene oxide has successfully coating on the surface of ZnO nanorods. With the optimizing the reduced graphene oxide/ZnO nanorords showed an excellent selectivity to NO2 and the minimum detection concentration was 0.5 ppm.

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