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Updated: Jun 22, 2026

Ammonia Synthesis at Low Pressure
Published on: August 23, 2017
Adsorption of ammonia on graphene
Hugo E Romero1, Prasoon Joshi, Awnish K Gupta
1Department of Physics, Pennsylvania State University, University Park, PA 16802, USA.
Abstract:
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.
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