本研究製備奈米金顆粒/發泡石墨烯複合材料，並將其應用於氨氣感測器。選用尺寸為10 mm × 10 mm、厚度1.7 mm的發泡鎳為基板，以化學氣相沉積法成長少層石墨烯於其上，並利用蝕刻方式去除鎳，即可得到一個具備三維網狀結構的發泡石墨烯。研究中亦利用無電鍍沉積法，將奈米金顆粒沉積於發泡石墨烯表面，並調整浸鍍參數，如溶液濃度及浸鍍時間，以得到不同的金顆粒大小與數量。發泡石墨烯之電洞載子濃度，於鍍金條件 (0.1 mM，10 sec) 之後，由5.50 × 1019 #/cm3增加至7.92 × 1019 #/cm3，顯示P型摻雜效果的提升。
結果顯示，發泡石墨烯於730 mg/m3純氨氣中達到接近1.0的感測靈敏度，並隨著氨氣量的增加呈現線性提升的關係。發泡石墨烯於空氣中，亦能對500 ppm氨氣達到0.68的感測靈敏度，而鍍金之發泡石墨烯，隨著奈米金顆粒數量增加、尺寸均勻性上升，其響應時間、回復時間有減少的趨勢，顯示對氨氣反應速率的提升。本元件製備方法簡單，室溫下對ppm濃度等級的氨氣有感測靈敏度，鍍金條件 (0.1 mM，10 sec) 之發泡石墨烯，在500 ppm氨氣中達到0.62的靈敏度，並且顯示極佳的可逆性及穩定性。因此，本研究製備之奈米金顆粒/發泡石墨烯複合材料，於室溫下的氨氣感測，具有相當的應用潛力。

This work fabricated gold-nanoparticle-decorated graphene foam composites which were applied to ammonia gas sensors. A three dimensional graphene foam was prepared through the chemical vapor deposition using Ni foam as substrate. Gold nanoparticles were deposited on graphene surface by the substrate-enhanced electroless deposition method. Gold particles with different sizes and number could be obtained by adjusting concentration of HAuCl4 solution and deposition time. The carrier concentration of graphene foam increased from 5.50 × 1019 #/cm3 to 7.92 × 1019 #/cm3 immersion in 0.1 mM HAuCl4 for 10 sec showing enhanced p-type doping.
Graphene foam showed sensitivity close to 1.0 under 730 mg/m3 ammonia and the sensitivity increased linearly with the amount of ammonia under vacuum background. Using air as background gas, graphene foam showed 0.68 sensitivity under 500 ppm ammonia, and gold nanoparticle-decorated graphene foam showed shorter response time and recovery time with the increase of amount and homogeneity of gold nanoparticles. The sensor prepared using the deposition condition of (0.1 mM, 10 sec) for gold nanoparticles showed reversibility and stability under 500 ppm ammonia exposure. In this study, we successfully synthesized gold nanoparticle-decorated graphene foam composite and demonstrated its promising potential in ammonia gas sensing.

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