紫外光對氧化石墨烯薄膜特性之影響

本研究使用固定濃度 (3 mg/ml)之氧化石墨烯 (Graphene oxide, GO) 水溶液，並利用食人魚溶液 (H2SO4:H2O2=7:3) 將石英基板做親水性的處理，以旋轉塗佈的方式 (轉速2000 rpm)來製作薄膜，再使用紫外光照射還原的方式在真空的環境下通入氬氣，改變照射的時間1 hr~10 hr，形成不同還原程度的還原氧化石墨烯薄膜(Reduced graphene oxide, RGO)，檢測其物理特性並觀察趨勢變化。首先以接觸角量測測得薄膜接觸角由23.63°上升至62.20°;AFM觀察表面形貌，還原前後的薄膜都會有皺褶的存在，但因能量的不足，使含氧官能基移除不完全，並觀察到還原後的薄膜會有團簇的生成，SEM觀察到的結果與AFM之結果相符。藉由EDS分析還原前後的碳氧比，結果顯示還原後的薄膜碳氧比由6:4降低為6:1，而拉曼分析結果，還原前的ID/IG比從1.83提升為還原後最高的2.24，代表經由紫外光的還原移除含氧官能基，使得缺陷變更多，得到成功還原的結果。我們也利用UV-vis檢測吸收光譜，隨著照射時間的拉長，代表碳氧鍵結的特徵峰被抑制，而電性量測則是使用Van der Pauw四點量測法量測電阻率，結果顯示紫外光還原確實能夠恢復薄膜電性，其中表現最好為照射9 hr之樣品，其電阻率為5.47×10-2 Ω-cm。

關鍵字

紫外光；氧化石墨烯

並列摘要

In this study, graphene oxide (GO) films were produced by spin coating and reduced by ultraviolet (UV) light. The films’ irradiation time was controlled and their properties were measured. First, we made the quartz substrates hydrophilic and dropped suitable graphene oxide solution on the substrates. Then we made graphene oxide films with 2000 rpm by spin coating. Finally, the films were reduced and transfered to the reduced graphene oxide films by UV light irradiation of 1~10 hours. We observed that the GO films’ contact angle rised from 23.63°to 62.20°. The surface morphology by Atomic Force Microscopy (AFM) and Scanning Electron Microscopy (SEM) showed that the films before and after reduction were formed with wrinkles, and all the films which had been irradiated by UV light generated clusters. Energy-dispersive X-ray spectroscopy (EDS) analysis showed that the carbon-oxygen ratio of the successfully reduced film was reduced from 6:4 to 6:1. The Raman analysis showed that the ID/IG ratio was increased from 1.83 (before the reduction) to 2.24 (after the reduction). It is because UV-light reduction removed oxygen-containing functional groups and induced more defects. We also used UV-vis spectroscopy to detect the light absorption of the films. After irradiation the peak which means the bond between carbon and oxygen would inhibit. The electrical resistivity was measured by the Van Der Pauw four-point measurement method. The results showed that the lowest resistivity of the films was 5.47×10-2 Ω-cm in the sample of 9 hour UV light irradiation.