相工程化的拓撲半金屬（MoxW1-xTe2）的合成及其作為高性能能量轉換和儲存設備的應用

Abstract

MoxW1-xTe2 是一種吸引人的類型-II Weyl半金屬，由於其在理論上預測的超高載流 子遷移率、可調的穩健拓撲表面態以及多態相特性而引起了巨大的關注。 這些獨特 的特性為研究 MoxW1-xTe2 的電子轉換和儲存特性鋪平了道路，使其在催化領域具有 應用前景，用於開發高效和結構穩定的新一代催化劑，以及開發高容量和耐用的能 量存放裝置。 在本研究中，我們展示了合理的催化劑設計，包括合成和應用高度結 晶的 MoxW1-xTe2 晶體，直接用作染料敏化太陽能電池（DSSCs）中無鉑對電極（CE），以及用作鋰離子電池器件的陽極電極材料。 在第1章的第一節中，將介紹Weyl半金屬的基本背景，以及DSSCs和鋰離子 電池的工作原理。 第2章將展示一種簡便的CVD合成方法，用於在大氣壓下相調控 的幾層 MoxW1-xTe2 奈米晶體和薄膜。 將進行基本的光學和結構表徵，如光學顯微鏡 （OM）、拉曼光譜、X射線光電子能譜（XPS）、掃描電子顯微鏡（SEM）和高解 析度透射電子顯微鏡（TEM），以優化CVD合成程式，適用於兩種應用。 在第2章中探討採用場效應晶體管（FET）和四探針霍爾效應測量方法，研究 相調控的 MoxW1-xTe2 特性的獨特電學特性。 最後一節將重點介紹電化學測量，以展 示合成的相調控 MoxW1-xTe2 作為DSSCs中無鉑對電極和鋰離子電池中陽極電極的潛 在應用。 在第3章中，描述 MoxW1-xTe2 作為DSSCs中無鉑對電極的潛在應用，以及實 驗結果， 並討論電解液中電極的材料性能和穩定性。 在第4章中，重點介紹 MoxW1-xTe2 作為鋰離子電池的另一個潛在應用，用於插 層Li+電荷，由於其在電池電池器件中的應用。 將在碳布基底上沉積各種相的 MoxW1-xTe2 奈米晶體。 此外，除了晶體相特性外，還將通過原位TEM表徵方法研究 Li+的插層能力。 將通過電化學方法製備電池器件，以研究所製備晶體的充放電容量。還將討論器件穩定性的特性屬性和額外的表徵方法。 在第5章中，對我的整體工作進行總結和展望。 第6章將包括一般程式的附錄。最後，所有章節的參考文獻可在第7章找到。

MoxW1-xTe2 is an attractive type-II Weyl-semimetal that has garnered tremendous interest due to its theoretically predicted ultra-high carrier mobility, tunable robust topological surface states, and polymorphic phase properties. These unique characteristics pave the way to study the electron conversion and storage properties of MoxW1-xTe2, making it applicable in catalysis for developing highly efficient and structurally stable newgeneration catalysts, as well as for developing high-capacity and durable energy storage devices. In this study, we demonstrate rational catalyst design, which includes the synthesis and application of highly crystalline MoxW1-xTe2 crystals for direct use as a Pt-free counter electrode (CE) in dye-sensitized solar cells (DSSCs) and as an anodic electrode material for lithium-ion battery devices. In the first section of Chapter 1, the basic background of Weyl-semimetals along with the working principles of DSSCs and lithium-ion batteries are introduced. Chapter 2 demonstrates a facile CVD synthesis approach for phase-engineered few-layer MoxW1-xTe2 nanocrystals and thin films under atmospheric pressure. Basic optical and structural characterizations such as optical microscopy (OM), Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), and highresolution transmission electron microscopy (TEM) have been performed to optimize the CVD synthesis procedures for both applications. In the second section, field-effect transistor (FET) and four probe Hall-effect measurements are employed to study the distinctive electrical properties of phase-engineered MoxW1-xTe2 characteristics. The final section focuses on electrochemical measurements to demonstrate the potential application of the synthesized phase-engineered MoxW1-xTe2 as a counter electrode for DSSCs and as an anodic electrode in lithium-ion batteries. In Chapter 3, the potential applications of MoxW1-xTe2 as a Pt-free counter electrode in DSSCs are described along with experimental results. The material performance and stability of electrodes in the electrolyte solution are discussed. Chapter 4 focuses on another potential application of MoxW1-xTe2 as an anodic electrode for lithium-ion batteries to intercalate Li+ charges due to its application in battery cell devices. Various phases of MoxW1-xTe2 nanocrystals have been deposited on carbon cloth substrates. Additionally, besides crystal phase characterization, the Li+ intercalation capability has been investigated through in-situ TEM characterization methods. Battery cell device fabrication has been performed electrochemically to study the charging/discharging capacity of the prepared crystals. Further characteristic properties of device stability and additional characterization methods are discussed. Chapter 5 provides a summary and outlook of my overall work. Chapter 6 includes an appendix of the general procedures. Finally, the references for all chapters are found in Chapter 7.