http://tdr.lib.ntu.edu.tw/jspui/handle/123456789/83233 Sat, 03 Oct 2026 10:34:48 GMT 2026-10-03T10:34:48Z http://tdr.lib.ntu.edu.tw/jspui/handle/123456789/103049 標題: 調控表面電子態與電荷分佈以促進光催化二氧化碳還原:從單原子設計到反應物介導機制; Modulating Surface Electronic States and Charge Distribution for Enhanced Photocatalytic CO2 Reduction:From Single-Atom Design to Reactant-Mediated Mechanisms 作者: 黃至揚; Chih-Yang Huang 摘要: 在人類人口成長以及科技的持續發展之下，能源需求日益增加，但是如果依靠使用傳統化石燃料會導致排放大量溫室氣體，加速全球暖化。因此尋求再生能源以及減少溫室氣體是目前全球的重要目標。其中，光催化二氧化碳還原反應(PC-CO2RR)能將溫室氣體轉化為高能量密度太陽能燃料的極具前景之途徑，然而其效率常受制於CO2分子的化學惰性以及遲緩的反應動力學。本論文結合實驗表徵與密度泛函理論(DFT)計算，從調控催化劑表面電子結構出發，系統性地探討了提高 CO₂ 活化與轉化效率的兩種創新策略。 第一部分研究成功透過濕浸漬法將過渡金屬單原子(Cr、Fe、Ni)錨定於氧化鎢(WO3)奈米片表面。擴展X射線吸收精細結構(EXAFS)證實了單原子的孤立分散狀態。研究提出以金屬的價電子數與電負度作為雙物理描述符的預測模型，指出 Fe 與 Mn 處於電荷轉化的協同最優點。光電子能譜(XPS、XAS)與計算皆證實，Fe 單原子能有效打破表面電荷分佈的對稱性，引導顯著的局部電荷積聚。這不僅增強了CO2的化學吸附(使其∠O-C-O鍵角劇烈彎曲至135.6o)，更大幅降低了速率決定步驟中*COOH 中間體的活化能障，使最初的質子化步驟轉變為自發的放熱反應。在 4 小時的光照測試下，最佳化的 SA-Fe-WO3 催化劑的一氧化碳(CO)產率達 12.1 µmol g⁻¹，較原始WO3提升了約三倍，表現出優異的穩定性與一氧化碳選擇性。 第二部分研究則聚焦於反應物吸附過程對催化劑電子態的動態反饋調控。我們以 20 奈米厚的二硫化鉬(MoS2)薄膜作為模型催化劑，並利用近常壓X射線光電子能譜(NAPXPS)進行原位觀測。研究首次發現反應物的吸附順序會劇烈影響能帶結構: H2O的先吸附會引導 MoS2 表面發生向下能帶彎曲(Downward band bending)，促使光生電子在MoS2表面大量積聚；而先吸附 CO2 則會引導微幅的向上能帶彎曲，反而增加了電子轉移的能壘。原位原創的環境依賴實驗與開爾文探針力顯微鏡(SKPM)及DFT計算相符，證實先通入H2O能大幅促進高活性彎曲態CO2 (b-CO2)中間體的形成，進而使隨後的光催化PC-CO2RR一氧化碳產率顯著提升20%。 綜上所述，本論文建立了電荷局域化、幾何活化與光催化性能之間的關聯，更展現了反應物調節能帶彎曲的動態行為，為設計下一代高效太陽能燃料催化表面提供了方向。; Rapid global population growth and industrialization have escalated energy demands, while reliance on conventional fossil fuels has accelerated global warming via greenhouse gas emissions. Developing renewable energy platforms and carbon mitigation strategies is therefore a paramount global objective. Photocatalytic CO2 reduction reaction (PC-CO2RR) offers a promising pathway to convert greenhouse gases into high-energy-density solar fuels; however, its efficiency remains severely constrained by the chemical inertness of the CO2 molecule and sluggish reaction kinetics. Here, by combining experimental characterizations with density functional theory (DFT) calculations, we systematically investigated two innovative strategies to modulate surface electronic structures for enhanced CO2 activation and conversion. First, isolated transition-metal single atoms (Cr, Fe, and Ni) were successfully anchored onto WO3 nanosheets via a wet-impregnation method, with their atomically dispersed states confirmed by extended X-ray absorption fine structure (EXAFS) spectroscopy. A predictive model utilizing the valence electron number and electronegativity of the metals as dual physical descriptors revealed that Fe and Mn occupy a synergistic optimum for charge transfer. XPS, XANES and DFT calculation demonstrated that Fe single atoms effectively broke the symmetry of the surface charge distribution, driving localized electron accumulation. This electronic localization significantly enhanced CO2 chemisorption—evidenced by a dramatic bending of the ∠O-C-O bond angle to 135.6°—and substantially lowered the activation barrier of the *COOH intermediate, rendering the initial protonation step a spontaneous, exothermic process. Consequently, the optimized SA-Fe-WO3 catalyst achieved a carbon monoxide (CO) yield of 12.1 µmol g−1 over 4 hours of illumination, representing a threefold enhancement relative to pristine WO3 while maintaining excellent stability and CO selectivity. Second, the dynamic feedback regulation of the catalyst electronic states induced by reactant adsorption sequences was explored. Utilizing a 20 nm thick MoS2 thin film as a model catalyst, in situ near-ambient pressure X-ray photoelectron spectroscopy (NAPXPS) revealed that the adsorption sequence dictates the surface band alignment. Specifically, the pre-adsorption of H2O induced a downward surface band bending on MoS2, promoting the accumulation of photogenerated electrons at the immediate surface. Conversely, pre-exposure to CO2 provoked a subtle upward band bending, which heightened the electron transfer barrier. This environment-dependent behavior, cross-validated by scanning Kelvin probe microscopy (SKPM) and DFT, confirmed that pre-introducing H2O significantly facilitated the formation of highly active b-CO2 intermediates, thereby boosting the subsequent CO yield by 20%. In summary, this thesis establishes a comprehensive correlation between charge localization, geometric activation, and photocatalytic performance, while unveiling the dynamic behavior of reactant-modulated band bending. These mechanistic insights provide a foundational design paradigm for engineering next-generation, highly efficient catalytic surfaces for solar fuel production. Thu, 01 Jan 2026 00:00:00 GMT http://tdr.lib.ntu.edu.tw/jspui/handle/123456789/103049 2026-01-01T00:00:00Z http://tdr.lib.ntu.edu.tw/jspui/handle/123456789/102967 標題: 神經網路位能加速之第一原理探索胜肽構形; A Neural Network Potential Accelerated First-Principles Study on the Conformational Landscapes of Peptide 作者: 同高孝; Dong Cao Hieu 摘要: 探索勝肽的構象空間對於理解其三維結構與分子穩定性之間的關係以及解讀光譜性質至關重要。然而，即使在低能量條件下，由於鏈長、質子化狀態、甲基化程度以及順反肽鍵異構體等因素的影響，應探索的結構數量龐大，因此窮舉式的搜尋在計算上仍然極具挑戰性。本論文發展了一種基於深度學習神經網路位能（DL-NNP）的迭代主動學習方法，旨在加速構象探索，同時保持接近密度泛函理論（DFT）的精確度。此框架結合了低成本採樣、NNP 引導的優化和 DFT 精修，能夠系統地研究甘氨酸寡聚體及甲基化多肽（三肽至六肽）的構象空間。在所有體系中，NNP 的能量預測誤差均低於 1 kcal/mol，同時與傳統基於 DFT 的工作流程相比，計算成本降低了 300 倍以上。一項關鍵進展在於證明，僅使用單點 DFT 能量和力即可訓練五肽和六肽的高精度 NNP，從而在不犧牲準確度的前提下降低訓練資料生成的成本。我們的結果表明，質子化和甲基化顯著穩定了順式胜肽構象，而甲基化亦會調節優先質子化位點。鏈長增加與 N-甲基化有助於促進兩性離子結構的穩定性，而隱式溶劑化則顯著增加了熱力學可及的低能構象異構體數量。總而言之，本研究顯示，基於主動學習的 DL-NNP 為探索胜肽構象空間提供了一個兼具高精度、可移植性與計算效率的框架，彌合了第一原理精度與大規模構象採樣之間的差距; Exploring peptide conformational landscapes is essential for understanding the relationships between molecular structure, stability, and spectroscopic properties. However, exhaustive conformational searches remain computationally challenging because of the large number of accessible structures arising from variations in chain length, protonation state, methylation pattern, and cis/trans peptide-bond isomerism. In this thesis, deep-learning neural network potentials (DL-NNPs) trained through iterative active learning were developed to accelerate conformational exploration while maintaining near-density-functional-theory (DFT) accuracy. The proposed framework combines low-cost conformational sampling, NNP-guided optimization, and DFT refinement, enabling systematic studies of glycine oligomers, methylated tripeptides, and polypeptides up to hexapeptides. Across all systems, the NNPs achieved energy prediction errors below 1 kcal mol⁻¹ while providing more than a 300-fold reduction in computational cost compared with conventional DFT-based workflows. A key methodological advance is the demonstration that accurate NNPs for penta- and hexapeptides can be trained using only single-point DFT energies and forces, substantially reducing the cost of training-data generation without sacrificing accuracy. The resulting conformational databases revealed that protonation and methylation significantly stabilize cis-peptide conformations, while methylation also modulates preferred protonation sites. Furthermore, chain elongation and N-methylation promote zwitterionic structures, whereas implicit solvation substantially increases the number of thermally accessible low-energy conformers. Overall, this work demonstrates that active-learning DL-NNPs provide an accurate, transferable, and computationally efficient framework for exploring peptide conformational landscapes, bridging the gap between first-principles accuracy and large-scale conformational sampling. Thu, 01 Jan 2026 00:00:00 GMT http://tdr.lib.ntu.edu.tw/jspui/handle/123456789/102967 2026-01-01T00:00:00Z http://tdr.lib.ntu.edu.tw/jspui/handle/123456789/96827 標題: 碲化銅中增強的波動狀電荷密度波序化促進電子的加速與輕化; The Growing Charge-Density-Wave Order in CuTe Lightens and Speeds up Electrons 作者: 汪奕達; I-Ta Wang 摘要: 隨著量子材料的出現，越來越多有趣的性質開始被大家研究並檢視。近年來，擁有在對稱保護下表現線性色散能帶的拓樸半金屬引起了大家的注意，這樣特殊的能帶結構，會造成特別的電荷屏蔽效應。我們利用電荷響應函數(Charge Response Function)去計算電磁易感率(Susceptibility)特別是電荷密度波(CDW)存在於材料中的情況，可幫助我們了解拓樸量子材料中有趣的電子結構。在本論文中，我們利用動量解析電子能量損失光譜(q-EELS)以及古典電漿子(plasmon)色散關係去偵測並且計算材料中載子的有效質量和費米速度，我們發現在碲化銅(CuTe)中，載子的有效質量和費米速度隨著電荷密度波序化的增強而分別變輕和增快，這與一般擁有電荷密度波的材料所表現的行為相反，也是本論文想要探討的主要目標。 在第一章中，我們對於量子材料和電荷屏蔽效應進行簡單的介紹，我們藉由對稱性的觀點切入量子材料，分別由反對稱中心和時間反演對稱中心以及破壞對於狄拉克(Dirac)和外爾(Weyl)費米子進行探討；我們也在電荷屏蔽的章節裡，簡單介紹電荷密度波、電漿子以及德汝德-勞倫茲模型(Drude-Lorentz Model)。在第二章，我們詳細的闡述掃瞄式穿透電子顯微鏡以及動量解析電子能量損失光譜的原理和應用。在第三章中，我們討論了關於碲化銅在動量解析電子能量損失光譜的結果，在不同動量空間下的光譜中，我們可以利用電漿子的色散關係得到相關載子的有效質量和費米速度，在碲化銅中，主要載子來源於線性色散能帶的輕電子以及與其垂直方向的重電洞。 在第四章中，我們探討在不同溫度下的動量解析電子能量損失光譜的實驗結果，因為隨著溫度低於電荷密度波相轉變溫度，電荷密度波序化會隨著溫度降低而增強，我們可以觀察電荷密度波序化增強與載子的關係。在室溫時，線性色散能帶的電子，同時也是與電荷密度波序化相關的載子，其有效質量約為0.28倍的電子靜止質量(m0)，而其費米速度則約為光速的0.005倍。隨著溫度的降低和電荷密度波序化的增強，我們發現輕電子的有效質量變得更輕並且費米速度變得更快。在溫度到100 K時，載子的有效質量和費米速度相對於室溫時，變輕和增快約百分之20。我們推測，造成這樣的原因，是因為線性色散的能帶在低溫下進行能帶的重整化(Band Renormalization)，使得能帶變的更陡峭，進而導致載子的有效質量變輕，以其費米速度增快。 電荷密度波隨著不同溫度下的序化現象在材料中有著重要的地位，碲化銅是一個適合針對電荷密度波以及弱相關系統進行研究的材料，而在適當的條件下，動量解析電子能量損失光譜更可以助於我們瞭解材料內的物理現象以及計算重要的物理參數，我們期待在更多擁有豐富物理性質的材料上，利用動量解析電子能量損失光譜獲得更加有趣的實驗結果。; With the rapid advances discovery in various systems, quantum materials have aroused lots of attention in the field. Recently, topological semimetals featuring symmetry-protected crossing of linearly dispersing bands in the bulk electronic structure has gained growing attentions in the investigation of the electronic screening due to a finite density of states. Those unique material systems become interested with the concept of the matters susceptible to electronic ordering, where charge density waves (CDWs) are pervasive orders in the systems. The capability to probe the carrier density near the Fermi level inside the CDW systems in topological quantum matters allows a direct unveiling observation of the electronic structure. This Ph.D. thesis has been dedicated to the momentum-dependent electron energy loss spectroscopy (q-EELS) on probing the effective mass and the Fermi velocity without further experiment setup. The reduced effective mass and the enhanced Fermi velocity in our CuTe system with CDW order growing exhibits an inverse result to the usual CDW systems. A general introduction to the quantum materials and the charge response phenomena is presented in Chapter 1 and the experimental elucidation is addressed in Chapter 2. In Chapter 3, we show the q-EELS experimental result on the CuTe crystal, where we can obtain the effective mass and the Fermi velocity using the classical plasmon dispersion relation. We can simultaneously capture the effective mass and the Fermi velocity of the related, practically linearly dispersing electron and the counterpart of heavy-hole carrier. In Chapter 4, we show the temperature dependent q-EELS experiment across the transition temperature 335 K (TCDW, CDW transition temperature) to help to observe the change followed the CDW order growth. The effective mass of practically linearly dispersing electron relating to CDW gap opening is 0.28 m0 (m0, the electron rest mass) and the Fermi velocity is approximate 0.005 c (c, the speed of light) at room temperature. Following the CDW order growth, the electrons becomes lighter and moves faster by ~20% toward to 100 K. Thorough inspection below TCDW unveils the essential role of the increasing opening of the CDW gap. CuTe is a rich platform for the exploration of CDW and weak-coupled correlation physics with q-EELS as a useful tool for probing the associated fundamental properties. Mon, 01 Jan 2024 00:00:00 GMT http://tdr.lib.ntu.edu.tw/jspui/handle/123456789/96827 2024-01-01T00:00:00Z http://tdr.lib.ntu.edu.tw/jspui/handle/123456789/96365 標題: 用於高效水分解的原子層電催化劑設計; Atomically engineered electrochemical catalysts for efficient water splitting. 作者: 陳定睿; Ding-Rui Chen 摘要: 可再生能源需求的增長引起了世界對於水分解反應（2 H2O → 2 H2 + O2）的高度興趣，也突顯了高效催化劑的重要性。二維（2D）材料，如二硫化鉬（MoS2）的邊緣，展現了匹配的ΔGH*並具有作為析氫反應（HER）催化劑的潛力，然而這些材料的動力學尚未完全理解和解決。 在本論文中，我們首先研究了以邊緣主導的超窄MoS2 奈米帶陣列的電化學反應動力學表現。然後，我們通過二維邊緣的凡得瓦（vdW）堆疊實現了多位點電催化，除了透過實驗和模擬結果確認了優良的HER 和OER（析氧反應）以及多位點間中間體的交換反應，我們還展現了十分良好的整體水分解反應效果。 為了研究邊緣主導的電化學反應動力學，我們首先開發了一種模板減法圖案化方法（TSPP）。該型態工程法使我們能夠建立長距離、高密度和高質量的基面超窄奈米帶陣列，充當探索邊緣主導電化學的實驗平台。小於30 奈米的奈米帶陣列在評估電化學特性時展現出增強的HER動力學。由光電催化測量和載流子傳輸模擬證明這些改進是由於從基面向邊緣位置的電荷轉移效率的提高所貢獻的。我們的結果展示了邊緣主導電催化在HER 中的潛力，並為奈米帶製造和奈米帶增強電化學提供了一種有望的策略。 接著，我們繼續擴展透過vdW 堆疊2D 邊緣實現多位點邊緣催化。透過結合實驗與模擬結合，我們證明了vdW 堆疊活性位點在HER 中表現出協同作用，並確認了相鄰位點之間的中間體交換。此外，我們的結果展示了HER 和OER 的增強效果，優於均質疊層材料。vdW 堆疊的多位點催化成功應用於中性水分解微反應器，並表現出卓越的性能。; The growing demand for renewable energy has sparked interest in water-splitting reactions (2H2O → 2 H2 + O2), highlighting the crucial role of high-performance electrocatalysis.Two dimensional (2D) materials such as Molybdenum Disulfide (MoS2) edges exhibit the best matched ΔGH* for hydrogen evolution reactions (HER) if their kinetics can be addressed and understood. In this thesis, we first investigated the electrochemical reaction kinetics of edge-dominated ultranarrow MoS2 nanoribbon arrays. Then, multi-site electrocatalysis was achieved through the van der Waals (vdW) stacking of 2D edges. In addition to confirming excellent Hydrogen Evolution Reaction (HER) and Oxygen Evolution Reaction (OER), as well as intermediate exchange reactions through experimental and simulation results, we also demonstrated excellent performance in the overall water splitting reaction. To investigate edge-dominated electrochemical reaction kinetics, we first developed a morphological engineering method called the templated subtractive patterning process (TSPP). This method enables us to establish a long-range, high-density, and high-quality basal plane ultra-nanoribbon arrays, acting as an experimental platform for exploring edge-dominated electrochemistry. Sub-30nm nanoribbons demonstrate significantly enhanced HER kinetics through assessed electrochemical characterizations. These improvements are due to increased charge transfer efficiency from the basal plane toward the edge sites as revealed by Photo-electrocatalytic measurements and carrier transport simulations. Our findings demonstrate the potential of edge-dominated electrocatalysis for HER and provide a promising strategy for nanoribbon fabrication and nanoribbon-enhanced electrochemistry. Afterward, we extended our exploration to realize multi-site edge catalysis by forming vdw 2D edges. Combining direct experimental evidence and Ab-initio simulations, we demonstrated that vdW stacking at active sites exhibits synergistic interactions in the HER, and the exchange of intermediates between neighboring sites was confirmed. Furthermore, our results showcased enhanced efficiency in HER and OER, outperforming homogeneous materials. The vdw stacked multi-site catalysis were successfully applied to neutral water-splitting microreactors, demonstrating superior performance. Mon, 01 Jan 2024 00:00:00 GMT http://tdr.lib.ntu.edu.tw/jspui/handle/123456789/96365 2024-01-01T00:00:00Z