Abstract
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.