Improved sorption characteristics of NH3 molecules on the solution-processed graphene sheets

In this report, we investigated solution-processed graphene chemical sensors. A vacuum-annealing process after the graphene sheets were deposited on the wafer enhanced the response and sensitivity of the sensors by increasing the number of pristine sites on graphene. The presence of defect sites with higher binding energies and lower populations was related with slow adsorption/desorption. In contrast, fast adsorption/desorption were observed from the pristine sites. A two-step adsorption/desorption mechanism was observed when graphene sheets were exposed to ammonia molecules.