Ag₂S nanoparticles decorated graphene as a selective chemical sensor for acetone working at room temperature

Decorating graphene with nanoparticles is an effective method for improving gas selectivity and sensitivity of graphene-based chemical sensors. We report herein the enhancement of the gas selectivity and improved response of a graphene-based chemical sensor by decorating the graphene with synthesized Ag₂S nanoparticles. To synthesize uniformly sized Ag₂S nanoparticles, we used the ultrasonic irradiation method, and then the synthesized Ag₂S nanoparticles were decorated onto graphene uniformly, by using a simple spin coating method. Gas responses of the resulting chemical sensor were tested for volatile organic compounds (VOCs) such as acetone, ethanol, and hexane. While no noticeable gas response changes were obtained for ethanol and hexane vapors, a dramatic increase of ~660% resulted from exposure of the sensor to acetone vapor. In order to determine the mechanism behind the excellent acetone response of graphene decorated with Ag₂S nanoparticles, density functional theory (DFT) calculations were performed, and showed higher binding energies and electron transfer between Ag₂S and acetone than between Ag₂S and the other VOCs. This result indicated that decorating graphene with nanoparticles displaying a high binding energy for the target gas is an efficient way to improve the gas selectivity and response levels of graphene-based chemical sensors.