NO2 감지를 위한 금속 이온 도핑 ZnO 나노 구조 기반 선택적 민감 저항 센서 연구 : ZnO 나노 구조 기반 선택적 민감 저항 센서 연구 = Study on a selective and sensitive resistive sensor based on metal ion-doped ZnO nanostructures for NO2 detection

다국어 초록 (Multilingual Abstract)

Gas sensors serve as vital functional devices that detect and alert us to the presence of hazardous gases in our surroundings. Their reliable and efficient operation is essential to protect both human life and property from unexpected accidents or potential damage. Consequently, the performance of gas sensors—especially their sensitivity and selectivity—is directly linked to ensuring human safety. This dissertation focuses on advancing materials synthesis and optimizing fabrication techniques to improve these key performance parameters. The present work aims to significantly improve the sensitivity and selectivity of gas sensors, strengthening their ability to detect and respond to hazardous gases with greater accuracy and reliability. Metal oxide semiconductor based nanostructures represent one of the most promising classes of materials for chemical gas sensing, owing to their tunable physicochemical properties and compatibility with miniaturized device fabrication. These materials have been extensively employed for the detection of a wide range of chemical species. Over the past few years, technologically important binary semiconductor nano-structured oxides, such as ZnO, have attracted considerable interest due to their unique properties and potential use in gas sensor device applications. There is now growing interest in a wide range of zinc-based nano-structures, which offer even greater possibilities. Much research today is focused on tailoring the properties of ZnO through doping with metal ions for efficient use in gas sensing applications. In this context, the present work focuses on the synthesis of pure and doped ZnO nanomaterials, prepared in both powder and thin-film forms, and their systematic investigation for potential chemical sensing applications. This dissertation is mainly divided into five chapters. The first chapter provides a brief introduction and overview of gas sensors, highlighting their basic operating mechanisms, key performance parameters, current challenges, and their various applications. Additionally, this chapter outlines the objectives, and overall organization of the dissertation. The second chapter presents a detailed description of the synthesis of In third chapter, we study the role of nickel (Ni) doping in ZnO nanoparticles as a gas sensor. The structural, morphological, chemical and optical properties of these samples were investigated, and the effect of Ni doping on the properties was investigated. These samples were investigated for the detection of NO2 gas, and the relationship between the sensing activity and the doping-induced properties was discussed in detail. In fourth chapter, the gas-sensing behavior of cobalt-doped ZnO nanostructures is systematically investigated. The nanostructures were synthesized via a simple probe sonication technique, and their structural, morphological, optical, and chemical properties were thoroughly characterized using various analytical methods. These materials were then used to fabricate sensor films for NO₂ detection, a major environmental pollutant. Particular attention is given to the influence of cobalt doping on the physicochemical properties of ZnO and its correlation with enhanced NO₂ sensing performance. The chapter is organized into two sections: the first presents a detailed analysis of the structural, morphological, optical, and chemical characteristics as a function of cobalt concentration, while the second discusses the gas-sensing performance of the resulting nanostructures. The fifth chapter provides a brief conclusion of the key findings from all preceding chapters and outlines possible directions for future work In summary, this dissertation investigates how synthesis conditions affect the structural, morphology and chemical states of ZnO and their impact on gas sensing performance. Systematic studies of various synthesis parameters and doping levels provide insight into the optimization of ZnO nanomaterials, enabling the development of gas sensors with increased sensitivity and selectivity.

목차 (Table of Contents)

• 국문초록 i
• 목 차 ii
• 표 목 차 iii
• 그림목차 iv
• 제 1장 서론 1
• 1.1. 개요 1
• 1.2. 가스센서의 역사적 배경 6
• 1.3. 가스센서 분류 8
• 1.3.1. 가스센서 분류 기준 8
• 1.3.2. 전기화학식 가스센서 9
• 1.3.3. 반도체식 가스센서 10
• 1.3.4. 복합식 가스센서 11
• 1.3.5. 광학식 가스센서 12
• 1.4. 금속산화물 기반 반도체식 가스센서 13
• 1.4.1. 금속산화물 기반 반도체식 가스센서의 작동
• 원리 및 대표 소재 13
• 1.4.2. 금속산화물 기반 반도체식 가스센서의 물질별
• 연구 동향 15
• 1.4.3. 금속산화물 나노구조체 29
• 제 2장 솔보서멀(Solvothernal)법으로 합성된 ZnO 나노구조와
• NO2 검출을 위한 가스 감지 성능 50
• 2.1. 개요 50
• 2.2. 실험방법 54
• 2.2.1. 재료(Materials) 54
• viii
• 2.2.2. 합성방법(Synthesis) 54
• 2.2.3. 분석(특성) 평가(Characterization) 55
• 2.3. 결과 및 고찰 58
• 제 3장 NO2 가스 검출을 위한 니켈(Ni) 도핑 ZnO 나노 입자 ·· 73
• 3.1. 개요 73
• 3.2. 시험 세부 사항 76
• 3.2.1. 재료(Materials) 76
• 3.2.2. ZnO 및 Ni 도핑된 ZnO의 프로브 초음파 처리
• 보조 합성 76
• 3.2.3. 특성화 77
• 3.3. 결과 및 고찰 78
• 3.4. NO2 가스 감지 89
• 제 4장 NO2 가스 검출을 위한 코발트(Co) 도핑 ZnO 나노
• 입자 98
• 4.1. 개요 98
• 4.2. 시험 세부 사항 101
• 4.2.1. 재료(Materials) 101
• 4.2.2. ZnO 및 Co 도핑 ZnO의 프로브 초음파 처리
• 보조 합성 101
• 4.2.3. 특성화 102
• 4.3. 결과 및 고찰 102
• 제 5장 결론 및 향후 전망 125
• 5.1. 결론 125
• 5.2. 서보노멀(Solvothermally) 합성 ZnO 나노구조와 NO2
• 검출을 위한 가스감지성능 125
• 5.3. NO2 가스의 가역적 및 선택적 검출을 위한 니켈
• 도핑 ZnO 나노입자 126
• 5.4. NO2 검출에 대한 가역성 및 선택성 향상을 위한
• ZnO 격자에서 Co 도핑의 역할 126
• 5.5. 향후 전망 127
• 참고문헌 129
• Abstract 139