Reduced graphene oxide as an over-coating layer on silver nanostructures for detecting NH3 gas at room temperature

Reduced graphene oxide (rGO) nanosheets as an over-coating layer on silver nanoparticles (rGO/AgNPs) and silver nanowires (rGO/AgNWs) have been fabricated using solution processes and tested for NH3 gas detection in nitrogen/air at room temperature (RT). When exposed to 100 ppm NH3, the rGO/AgNWs device exhibited an excellent sensitivity (15%) compared to the rGO/AgNPs, rGO, and AgNWs devices. Our results revealed that the underneath AgNWs play a role as a network for providing a carrier transfer pathway, thus the rGO/AgNWs gas sensor device showed a stable, reproducible response and full recovery in nitrogen at RT. However, an excess amount of the AgNWs resulted in the agglomeration of the AgNWs. Consequently, a defective rGO over-coating layer with appearance of the pits was formed, reducing the sensitivity due to the adsorption deficiency.