Co-porphyrin functionalized CVD graphene ammonia sensor with high selectivity to disturbing gases: hydrogen and humidity
Keisuke Sawada, T. Tanaka, Takamune Yokoyama, Ryosuke Yamachi, Yuki Oka, Yusuke Chiba, Hiroshi Masai, Jun Terao, Ken Uchida
Abstract
Abstract Recently low-power, small gas sensors have been strongly demanded to realize “super smart society.” In particular, ammonia: NH 3 sensors are expected to be key devices for breath diagnosis. However, it is difficult for NH 3 sensors to obtain high selectivity against hydrogen: H 2 , since conventional metal-oxide gas sensors respond to any reducing gases. In this study, Co-porphyrin functionalized graphene sensors were fabricated, and selective NH 3 sensing was realized by the selective metal-ligand bond of Co with NH 3 . The sensor successfully detected sub-ppm NH 3 , while it showed no response to high concentration H 2 . Furthermore, we investigated the effect of humidity on the Co-porphyrin functionalized graphene NH 3 sensor. We demonstrated the detection of low concentration NH 3 even under rapid humidity changes. We considered that the key sensing mechanism of our sensor is charge transfer to graphene by the electronic structure change of Co-porphyrin-graphene complexes due to NH 3 adsorption on Co-porphyrin.