에너지 저장과 전환을 위한 그래핀 기반 나노구조물질의 전기화학 합성 연구

학위논문 (박사) -- 서울대학교 대학원 : 융합과학기술대학원 융합과학부(나노융합전공), 2020. 8. 박원철.Over the past decade, graphene-based nanomaterials have attracted significant research interest for their potential application in energy storage/conversion devices. However, the high cost and low supply limit their use in practical energy storage/conversion applications. Chemical synthesis is regarded as a scalable and low-cost process to produce graphene and graphene nanoribbons (GNRs), but the method involves the use of strong oxidants, which may cause explosion risk and serious environmental pollution. Recently, electrochemical processes have been explored as an attractive approach to prepare graphene-based materials because of their eco-friendly nature, and easy scalability. In this thesis, I aim to describe the electrochemical preparation of graphene and GNRs and their use in energy storage/conversion applications (i.e., Li-ion batteries and electrocatalyst for hydrogen evolution reactions). The first section of this thesis is dedicated to the electrochemical exfoliation of graphite into graphene. Electrochemical exfoliated graphene (EG) is used as a microwave susceptor to prepare a carbon-coated silicon-graphene nanocomposite film. The graphene absorbed the microwave radiation and generated heat which reduced the oxidized graphene and carbonized the polydopamine carbon precursor on the silicon nanoparticles. The prepared carbon-coated silicon−graphene nanocomposite was used as a lithium-ion battery anode. The electrochemical process was then extended to the preparation of a GNR. Previously, anodic oxidation in diluted sulfuric acid was used to unzip multi-walled carbon nanotubes (MWCNTs). However, several reports have shown that this method is incapable of selective unzipping. In this study, for the first time, electrochemical unzipping is performed by anodic oxidation of MWCNTs in concentrated sulfuric acid. When the MWCNTs are anodically oxidized in a concentrated acid electrolyte, they become longitudinally unzipped to form GNRs. Thus, the as-prepared GNRs were used as an anode for alkali ion capacitors in both organic and aqueous electrolytes and MoS2 catalyst support for the hydrogen evolution reaction. This thesis provides details of the electrochemical methods used to prepare graphene and GNRs. Such methods may pave the path for industrial production and applications of graphene and GNRs at a low cost.지난 10 년 동안 그래핀 기반 나노 물질들은 에너지 저장 및 전환 분야에서 우수한 물리적 및 화학적 특성으로 인해 연구가 활발히 이루어졌으나 높은 가격과 낮은 생산성으로 인해 상용화하기에는 어려움이 많았다. 현재 그래핀 및 그래핀 나노리본은 저렴하고 단순한 화학적 공정을 통해 합성할 수 있지만, 아직도 폭발의 위험성과 합성에 사용되는 강산화제 또는 강환원제로 인해 환경 오염을 유발시키는 문제점을 갖고 있다. 본 학위논문에서는 이러한 문제점들을 해결할 수 있는 전기화학법을 사용해 그래핀 및 그래핀 나노리본을 합성하였다. 첫번째 연구에서는 그래핀은 전기화학적 방법 중 하나인 산화 박리법을 이용해 합성되었다. 전기 화학적 박리된 그래핀은 마이크로파를 흡수하여 열을 발생시켰다. 발생된 열은 그래핀을 환원시켰고 동시에 실리콘 나노 입자에 코팅된 폴리 도파민 탄소 전구체를 탄화 시켰다. 탄소 코팅 된 실리콘 나노 입자-그래핀 복합체는 리튬 이온 배터리 음극으로 사용되었다. 다음으로는 전기 화학적 방법 중 하나인 삽입법을 사용하여 다중 벽 탄소 나노 튜브 (MWCNT)를 압축 해제(unzipping) 하였다. MWCNT가 진한 황산 전해질에서 전기화학적으로 산화될 때, 황산이 MWCNT 내부로 삽입되고, MWCNT가 압축 해제 되 그래핀 나노리본이 형성된다. 합성된 그래핀 나노리본은 유기와 수계 전해질에서 알칼리 이온 커패시터 전극, 수소 발생 반응을 위한 MoS2 촉매 지지체로 사용되었다. 본 학위논문에서는 전기화학방법을 이용해 그래핀과 그래핀 나노리본을 합성하는 방법을 제시하였다. 본 연구의 결과들은 그래핀 나노물질들을 산업에 응용하는데 있어서 유용하게 사용될 수 있으며 실제 제품에서 적용되는 것을 앞당길 수 있을 것으로 기대한다.Chapter 1. Introduction 28 1.1. Graphene and graphene nanoribbon 28 1.2. Application of graphene and graphene nanoribbon for energy storage and conversion devices. 33 1.2.1. Active material 34 1.2.2. Inactive material 38 1.3 Synthesis strategies for graphene and graphene nanoribbon 44 1.3.1. Preparation of graphene 45 1.3.2. Preparation of graphene nanoribbon 50 1.4. Electrochemical method 52 1.4.1. Intercalation-functionalization 56 1.4.2. The electrochemical unzipping of graphene nanoribbon 62 1.5. Thesis Overview 67 1.6. Reference 70 Chapter 2. Electrochemically Exfoliated Graphene as a Novel Microwave Susceptor: the Ultrafast Microwave-assisted Synthesis of Carbon-coated Silicon-graphene Film as Lithium-ion Battery Anode 78 2.1. Introduction 78 2.2. Experimental Method 83 2.3. Results and discussion 88 2.4. Conclusion 117 2.5. References 118 Chapter 3. Facile and Scalable Approach to Develop Electrochemical Unzipping of Multi-walled Carbon Nanotubes to Graphene Nanoribbons 123 3.1. Introduction 123 3.2. Experimental Method 130 3.3. Results and discussion 138 3.4. Conclusion 183 3.5. References 185 Chapter 4. Conclusion and outlook 190 국문 초록 (Abstract in Korean) 193Docto

루푸스에서의 단백뇨 악화를 예측하는 새로운 소변 생체표지자로써의 비타민D 결합단백

학위논문 (석사)-- 서울대학교 융합과학기술대학원 : 분자의학및바이오제약학과, 2016. 8. 송영욱.Background: Lupus nephritis (LN) is a major complication of systemic lupus erythematosus (SLE), which occurs in up to 50% of patients. Conventional biomarkers for assessing renal disease activity are imperfect in predicting clinical outcomes associated with LN. The aim of this study is to identify urinary protein biomarkers that reliably reflect disease activity or predict clinical outcomes. Methods: A quantitative proteomic analysis of pooled urine samples was performed to identify urinary protein biomarker candidates that can differentiate between SLE patients with and without LN. Selected biomarker candidates were further verified using urine samples from a larger cohort of SLE patients (n = 121) presenting with LN (n = 62) and without LN (n = 59) by enzyme-linked immunosorbent assay (ELISA) to investigate their predictive values for LN activity measure. Furthermore, association between urinary level of selected panel of potential biomarkers and prognosis of LN was assessed with a 4-year follow-up study of renal outcomes. Results: Urinary vitamin D-binding protein (VDBP), transthyretin (TTR), and retinol binding protein 4 (RBP4) were significantly elevated in SLE patients with LN, especially in patients with active LN (n = 21), compared to those without LN. Among them, VDBP was well correlated with severity of proteinuria (Spearmans rho = 0.661, P < 0.001) and renal SLE disease activity index (renal SLEDAI) (Spearmans rho = 0.520, P < 0.001). In the 4 year follow-up, VDBP was found to be a significant risk factor (hazard ratio 9.627, 95% CI 1.698 to 54.571, P = 0.011) for the development of proteinuric flare in SLE patients without proteinuria (n = 100) after adjustments of multiple confounders. Conclusion: Urinary VDBP was not only correlated with proteinuria and renal SLEDAI, but also predicted the development of proteinuria in SLE patients.INTRODUCTION 1 PATIENTS AND METHODS 2 RESULTS 8 DISCUSSION 14 REFERENCES 19 TABLES AND FIGURES 27 ABSTRACT IN KOREAN 38Maste

Mycelium Tremella fucifomis TFCUV5 mutant strain having high growth rate and polysaccharide productivity and uses thereof

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