Adsorption of ammonia on graphene.
We report on experimental studies of NH3 adsorption/desorption on graphene surfaces. The study employs bottom-gated graphene field effect transistors supported on Si/SiO2 substrates. Detection of NH3 occurs through the shift of the source-drain resistance maximum ('Dirac peak') with the gate voltage. The observed shift of the Dirac peak toward negative gate voltages in response to NH3 exposure is consistent with a small charge transfer (f approximately 0.068 +/- 0.004 electrons per molecule at pristine sites) from NH3 to graphene. The desorption kinetics involves a very rapid loss of NH3 from the top surface and a much slower removal from the bottom surface at the interface with the SiO2 that we identify with a Fickian diffusion process.
Romero
Hugo E
HE
Department of Physics, Pennsylvania State University, University Park, PA 16802, USA.
Joshi
Prasoon
P
Gupta
Awnish K
AK
Gutierrez
Humberto R
HR
Cole
Milton W
MW
Tadigadapa
Srinivas A
SA
Eklund
Peter C
PC
D000327:Adsorption; D000641:Ammonia / Q000032:analysis / Q000737:chemistry*; D003460:Crystallization / Q000379:methods; D004563:Electrochemistry / Q000295:instrumentation* / Q000379:methods*; D004867:Equipment Design; D019544:Equipment Failure Analysis; D006108:Graphite / Q000737:chemistry*; D046911:Macromolecular Substances / Q000737:chemistry; D008422:Materials Testing; D008968:Molecular Conformation; D049329:Nanostructures / Q000737:chemistry* / Q000648:ultrastructure; D036103:Nanotechnology / Q000295:instrumentation; D010316:Particle Size; D013499:Surface Properties; D014159:Transducers; D014173:Transistors, Electronic
D046911:Macromolecular Substances; D000641:Ammonia; D006108:Graphite