Reversible and Irreversible Responses of Defect-Engineered Graphene-Based Electrolyte-Gated pH Sensors

详细信息    查看全文

• 作者：Sun Sang Kwon ; Jaeseok Yi ; Won Woo Lee ; Jae Hyeok Shin ; Su Han Kim ; Seunghee H. Cho ; SungWoo Nam ; Won Il Park
• 刊名：ACS Applied Materials & Interfaces
• 出版年：2016
• 出版时间：January 13, 2016
• 年：2016
• 卷：8
• 期：1
• 页码：834-839
• 全文大小：380K
• ISSN：1944-8252

文摘

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 (～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 6–8 mV/pH.