Reversible and Irreversible Responses of Defect-Engineered Graphene-Based Electrolyte-Gated pH Sensors
- Authors
- Kwon, Sun Sang; Yi, Jaeseok; Lee, Won Woo; Shin, Jae Hyeok; Kim, Su Han; Cho, Seunghee H.; Nam, SungWoo; Park, Won Il
- Issue Date
- Jan-2016
- Publisher
- AMER CHEMICAL SOC
- Keywords
- graphene; graphene mesh; electrolyte-gated field effect transistor; pH sensor; nanosensor; defect-mediated chemisorption; defect passivation
- Citation
- ACS APPLIED MATERIALS & INTERFACES, v.8, no.1, pp.834 - 839
- Indexed
- SCIE
SCOPUS
- Journal Title
- ACS APPLIED MATERIALS & INTERFACES
- Volume
- 8
- Number
- 1
- Start Page
- 834
- End Page
- 839
- URI
- https://scholarworks.bwise.kr/hanyang/handle/2021.sw.hanyang/24107
- DOI
- 10.1021/acsami.5b10183
- ISSN
- 1944-8244
- Abstract
- We have studied the role of defects in electrolyte-gated graphene mesh (GM) field-effect transistors (FETs) by introducing engineered edge defects in graphene (Gr) channels. Compared with Gr-FETs, GM-FETs were characterized as having large increments of Dirac point shift (similar to 30-100 mV/pH) that even sometimes exceeded the Nernst limit (59 mV/pH) by means of electrostatic gating of H+ ions. This feature was attributed to the defect-mediated chemisorptions of H+ ions to the graphene edge, as supported by Raman measurements and observed cycling characteristics of the GM FETs. Although the H+ ion binding to the defects increased the device response to pH change, this binding was found to be irreversible. However, the irreversible component showed relatively fast decay, almost disappearing after 5 cycles of exposure to solutions of decreasing pH value from 8.25 to 6.55. Similar behavior could be found in the Gr-FET, but the irreversible component of the response was much smaller. Finally, after complete passivation of the defects, both Gr-FETs and GM-FETs exhibited only reversible response to pH change, with similar magnitude in the range of 68 mV/pH.
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