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Chemical Transformation of One-dimensional Nanostructured Semiconductors for Thermoelectric and Sensing Applications

Title
Chemical Transformation of One-dimensional Nanostructured Semiconductors for Thermoelectric and Sensing Applications
Author
PARK, KeeRyung
Alternative Author(s)
박기륭
Advisor(s)
좌용호
Issue Date
2019. 8
Publisher
한양대학교
Degree
Doctor
Abstract
나노 물질(nano-materials)은 기존의 재료가 가지고 있는 특성에서 벗어나 독특한 물리적, 화학적 특성을 나타내기 때문에 각광 받고있다. 이러한 나노 재료는 물질의 크기를 나노스케일로 제어함으로써 높은 비표면적 및 양자구속효과를 통해 기존에 가지고 있던 물질의 특성보다 향상되거나 새로운 특성을 나타낸다. 다양한 나노 물질 중에서 1차원 나노구조는 3차원 벌크나 2차원 박막 및 0차원의 나노입자와는 다른 독특한 물리적, 화학적 특성을 나타내기 때문에 많은 연구가 진행되고 있다. 이러한 1차원 나노재료를 얻기 위해서는 재료의 조성, 크기, 형상 등을 제어하는 합성 기술이 매우 중요하다. 따라서 본 연구에서는 1차원 나노재료를 전기방사법과 전해증착법을 이용하였고 토포화학 반응(topochemical reation), 양이온 교환 반응(cation exchange reaction)과 커켄달 효과(kirkendall effect) 같은 화학적 변환을 융합하여 다양한 나노선(nanowire), 나노섬유(nanofiber), 나노튜브(nanotube) 구조를 합성하고 물질에 따른 열전 특성과 압전 센서 및 가스센서로 적용(application)에 대한 포괄적인 내용을 제 1 장에 다루었다. 제 2장에서는 전기방사법으로 Ag 나노섬유를 합성하고 Ag2Te 나노튜브를 토포화학반응을 동반하는 전해증착법을 이용하여 1차원 중공 나노구조 (hollow nanostructure)를 합성하였다. 그리고 양이온 치환 반응을 이용하여 PbTe, PbTe-Ag2Te, CdTe 나노튜브를 합성하였고, 열전소자로 특성을 확인하였다. 제 3장에서는 텔루륨(Te) 나노선을 수열합성법으로 합성하고 합성된 텔루륨 나노선과 PDMS 폴리머와 섞고 두 전극 사이에 균일하게 도포하고 전기장(electric field)을 인가하여 쉽게 텔루륨 나노선을 정렬하였다. 정렬된 PDMS-Te 필름을 압전소자로 만들어밴딩(bending) 테스트와 사람 팔에 적용함으로 압전 센서 특성을 확인하였다. 제 4장에서는 주석 (Sn) 과 구리 (Cu) 전구체를 전기방사법을 이용하여 SnO2-CuO 나노 튜브를 합성하였다. 이 때 600oC에서 소결 시 커켄달 효과로 인해 나노튜브구조가 합성된다. 이 나노튜브는 다공성 중공 구조를 갖기 때문에 높은 비표면적과 SnO2와 CuO의 p-n 정션(junction)의 영향으로 H2S 감지 특성을 향상시켰다. 마지막으로 5장에서는 전반적인 내용을 정리하였다.
Nanomaterials are attracting attention because they exhibit unique physical and chemical properties that deviate from the properties of conventional bulk materials. The nanomaterials have nanoscale controlling the size of the materials, which results in a high surface area and quantum confinement effect, resulting in improved properties or new properties. One-dimensional nanostructures are undergoing a great deal of research because they exhibit unique physical and chemical properties that are different from those of three-dimensional bulk, two-dimensional thin films and zero-dimensional nanoparticles. In order to obtain one-dimensional nanomaterials, we need to have a synthesis technique for controlling the composition, size, and shape of the material is very important. Therefore, in this study, one-dimensional nanomaterials were synthesized by electrospinning, electrodeposition and chemical transformations such as hydrothermal method, topochemical reaction, cation exchange reaction and Kirkendall effect. These synthetic processes were combined into various nanowires. The synthesized various one-dimensional nanostructures such as nanowire, nanofiber, and nanotube were applied to thermoelectric, piezoelectric sensor and gas sensor. In the chapter 2, Ag nanofibers were synthesized by electrospinning. Than Ag2Te nanotube were synthesized by electrodeposition to Te deposition on Ag nanofibers with proceeding a topotactic reaction. PbTe, PbTe - AgTe and CdTe nanotubes were synthesized from Ag2Te nanotubes by cation exchange reaction and their thermoelectric properties were confirmed. In the chapter 3, the tellurium (Te) nanowire is synthesized by hydrothermal method. The synthesized Te nanowires were mixed uniformly with PDMS polymer to be located the mixed PDMS-Te solution between the two electrodes. Then an electric field was applied to obtain linearly aligned the tellurium nanowire structures. Piezoelectric characteristic was confirmed by the using PDMS-Te film as a piezoelectric. In the chapter 4, SnO2-CuO nanotubes were synthesized by electrospinning including both of Sn and Cu precursors. When a calcination was performed at 600°C, the nanotube structure was synthesized due to the kirkendal effect. The nanotubes have a porous-hollow structure, which enhances the H2S sensing property due to having a high surface area and p-n junctions of SnO2 and CuO. In the last chapter 5, the finding and conclusions were summarized.
URI
http://dcollection.hanyang.ac.kr/common/orgView/000000110292https://repository.hanyang.ac.kr/handle/20.500.11754/109084
Appears in Collections:
GRADUATE SCHOOL[S](대학원) > FUSION CHEMICAL ENGINEERING(융합화학공학과) > Theses (Ph.D.)
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