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摘要
本研究使用波長為355
nm，脈衝寬度為28 ns之Nd:YVO4奈秒紫外光脈衝雷射對噴塗於PET基板上之還原氧化石墨烯材料進行表面改質。研究發現，當調控雷射參數為離焦、雷射輸出功率3W、雷射掃描速度200
mm/s時，即在低雷射脈衝能量密度(52.08 mJ/cm2)及高脈衝重疊率(99.17
%)下可在不發生材料剝蝕的情況有效將原試片片電阻值於115.33秒改質時間內自3.49x104
Ω/□大幅降低至70
Ω/□。經分析拉曼光譜儀及X光光電子能譜儀，此係因熱處理過程中移除還原氧化石墨烯所具有之氧化官能基團致材料結構缺陷減少，氧碳原子數比並自52.62
%下降至24.02 %，材料逐步由sp2鍵結取代原sp3鍵結。經分析比表面積及孔隙分佈測定儀，雷射表面改質前後吸附氣體的型式皆為巨孔隙之多層吸附，而比表面積則獲得提升，與共軛焦顯微鏡量測之介面展開面積比(Sdr)由0.48上升到5.88的趨勢一致，推測此與材料表面粗糙度相關參數大幅上升有關，如表面最大高度(Sz)自12.30
μm上升至355.47
μm，表面算術平均粗糙度(Sa)自0.76
μm上升至24.58
μm，表面均方根粗糙度(Sq)自1.01
μm上升至37.48
μm。於氣體感測實驗中，經雷射表面改質後試片在電子傳導速度提升、氣體與材料接觸機率增加下感測性能得到改善，並提升對NO2氣體之響應，分別在5
ppm、10
ppm、30
ppm、50
ppm濃度中具有2.5
%、4 %、5.3
%、6.2 %之響應率，且此試片在連續開關NO2氣瓶的測試中顯示具有穩定性，並具備長期可靠性及選擇性。
關鍵字：還原氧化石墨烯、紫外光脈衝雷射、表面改質、二氧化氮、電阻式氣體感測器、響應率、片電阻
Abstract
In this study, we report the laser-induced
surface modification of RGO film sprayed coating on PET
substrate conducted via nano-second pulsed
Nd:YVO4
UV laser of 355 nm
wavelength and 28 ns pulse width. Through controlling
the laser power and scanning speed at 3W and 200 mm/s
with a defocused beam radius, respectively, that is,
under low laser fluence(52.08 mJ/cm2) and high pulsed overlapping rate(99.17
%), the sheet resistance of the RGO film was reduced dramatically from
3.49x104
Ω/□ to
70
Ω/□ in 115.33 s without
ablating. By analyzing the decreasing defects in the
process of heat treatment by Raman spectroscopy and
X-ray photoelectron spectroscopy, the removal of
oxygen-containing functional groups was observed, the
O/C atomic ratio varied from 52.62 % to 24.02 %, the
main hybridization of carbon changed from sp3
to sp2 accordingly. Specific surface area &
pore size distribution analyzer indicated that the
adsorption mechanism remained constant before and after
laser irradiation - multilayer adsorption model of
macroporous particles. Meanwhile, the specific surface
area increased, which was in line with the increase of
Sdr from 0.48 to 5.88 measured by
3D confocal laser scanning microscope, we
inferred that the result was related to the variation of
surface roughness: Sz increased from 12.30 μm to 355.47
μm, Sa increased from 0.76 μm to 244.58 μm, and Sq
increased from 1.01 μm to 37.48 μm. In the gas sensing
experiment, the property of RGO film improved in sensing
NO2 due to the lifting electron conduction
velocity and the raising contact possibility between NO2
and the RGO film, the sensing response of NO2
in 5 ppm, 10 ppm, 30 ppm, 50 ppm concentration were 2.5
%, 4 %, 5.3 %, 6.2 %, respectively, it also showed a
high stability, long time reliability and selectivity.
Keywords：Reduced graphene oxide, Pulsed UV laser, Surface
modification, NO2, Resistive gas sensor,
Response rate, Sheet resistance
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