What retards the response of graphene based gaseous sensor

TL;DR

This paper investigates why graphene-based gas sensors have slow response times despite their atomic thickness, identifying a potential barrier as a key factor and proposing a modification method to enhance response speed.

Contribution

The study reveals the role of a potential barrier in delaying graphene sensor responses and demonstrates a modification strategy with Fe2O3 molecules to significantly improve response times.

Findings

Potential barrier > 0.7 eV hinders gas landing on graphene.

Modified graphene with Fe2O3 shows response time close to 500 μs.

Modification reduces the potential barrier, speeding up sensor response.

Abstract

Graphene based sensor to gas molecules should be ultrasensitive and ultrafast because of the single-atomic thickness of graphene, while the response is not fast. Usually, the measured response time for many molecules, such as CO, NH3, SO2, CO2 and NO2 and so on, is on the scale of minutes or longer. In the present work, we found via \emph{ab initio} calculations there exists a potential barrier larger than 0.7 eV that hinders the gas molecule to land directly at the defective sites of graphene and retards the response. An efficient approach to the problem is suggested as modifying the graphene sheet with other molecules to reduce the potential barrier and was demonstrated by a graphene sheet modified by Fe2O3 molecules that shows fast response to H2S molecule, and the calculated response time is close to the measured one, 500 $\mu$s.