Synthesis of Ag@rGO/g-C3N4 Layered Structures and Their Application to Toxic Gas Sensors: Effect of Ag Nanoparticles

In this work, graphitic carbon nitride (g-C3N4) was synthesized by simple pyrolysis of melamine, and it was hybridized with reduced graphene oxide (rGO) and silver nanoparticles (AgNPs) using a stepwise solution method. AgNPs were randomly distributed on the surface of rGO/g-C3N4 layered hybrid structure, forming Ag@rGO/g-C3N4 composite. It was disclosed that the Ag@rGO/g-C3N4 composite responded to both oxidizing and reducing gases at room temperature, and its response was greatly enhanced from those of pristine rGO and rGO/g-C3N4. The room temperature responses of the composite were estimated at - 95% and 8% for 50 ppm of NO2 and NH3, respectively. The roles of structural components were discussed, and a gas-sensing mechanism was proposed based on the respective roles. In particular, AgNPs turned out to play an important role in the gas-sensing activity.