그래핀/은 나노복합체의 제조와 플렉서블 센서의 응용

학위논문 (석사)-- 서울대학교 대학원 : 화학생물공학부, 2013. 2. 장정식.The fabrication of designable CVD-grown few-layer graphene is a promising research area for enhanced device performance. In this study, the few-layer graphene was grown on Cu foil by chemical vapor deposition (CVD) method and functionalized with oxygen plasma treatment under controlled conditions, such as exposure time, input power and distance between the graphene and the plasma electrode. Oxygen plasma treated few-layer graphene (OPFG) results in high surface energy, leading to effectively attracting Ag+ ions in electrostatic interactions. Interestingly, the distribution of the metal nanoparticles increased with increasing the exposure time and their diameters were controlled by UV irradiation. Uniform Ag nanoparticles (Ag NPs) with ca. 9 nm diameter were successfully decorated on the graphene surface. Moreover, the Ag NPs/OPFG nanocomposite (AgNP–G) film has excellent mechanical bendability and durability in a flexible system. Furthermore, flexible hydrogen sensor of AgNP-G showed highly sensitive and reversible at room temperature (Minimum detection level, ca. 40 ppm)Contents Chapter 1. Introduction 1 1.1 Graphene nanocomposites 1 1.1.1 Synthetic methods of graphene/metal nanocomposites 2 1.1.1.1 Graphene oxide (GO)/metal nanocomposites 4 1.1.1.2 CVD-grown graphene/metal nanocomposites 5 1.1.2 Application of graphene/metal nanocomposites based flexible sensor 6 1.2 Objective of this study 7 Chapter 2. Experimental 9 2.1 Materials 9 2.2 Preparation of CVD-grown few-layer graphene 10 2.3 Surface engineering of graphene 11 2.4 Synthesis of graphene decorated with Ag nanoparticles 11 2.5 Electrical measurement of sensitivity in AgNPs-G sensor 12 2.6 Characterization 13 Chapter 3. Results and discussion 15 3.1 Fabrication of OPFG and its characterization 15 3.1.1 Mechanism of functionalization on graphene surface 15 3.1.2 Raman and XPS analysis of OPFG film with different plasma treatment factors 16 3.1.3 Surface energy analysis of OPFG film with different plasma treatment time 27 3.2 Fabrication of AgNPs-G and its characterization 31 3.2.1 Mechanism of AgNPs-G in photoreduction process 33 3.2.2 AFM, XPS, and TEM analysis of AgNPs-G film 36 3.2.3 Electrical and mechanical properties of AgNPs-G in a flexible system 43 3.3 Application of AgNPs-G based flexible hydrogen sensor 48 Chapter 4. Conclusion 53 References 55 Abstract 61Maste