Graphene Functionalization by O2, H2, and Ar Plasma Treatments for Improved NH3 Gas Sensing
Sogo Iwakami1, Shunya Yakushiji1, Tomonori Ohba1
1Graduate School of Science, Chiba University, 1-33 Yayoi, Inage, Chiba 263-8522, Japan.
Abstract:
Graphene-based materials have gained attention for their promise in various applications owing to their two-dimensional structure. Functionalizing the graphene surface can help realize materials with noble properties. In this study, graphene was functionalized by plasma treatment in O2, H2, and Ar environments, and the effects on the NH3 gas-sensing performance were evaluated. The O2 plasma treatment induced oxidation of the graphene (i.e., graphoxide), while the H2 plasma treatment induced hydrogenation (i.e., graphane). Raman scattering spectroscopy suggested that graphoxide had vacancy-type defects and graphane had sp3-type defects, while Ar-treated graphene had both types of defects. Graphane had the highest sheet resistance followed by graphoxide, Ar-treated graphene, and pristine graphene, which can be attributed to the large bandgap of 3.0 eV for graphane. In contrast, graphoxide had the best NH3 gas-sensing performance, which indicates that NH3 gas interacts more strongly with vacancy-type defects than with sp3-type defects. The results showed that functionalizing the graphene structure generated noble materials with a superior NH3 gas-sensing performance compared with pristine graphene.
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