隨著全球能源消耗日益加劇以及氣候變遷問題日益嚴峻，學者們積極尋求替代方法以更潔淨、永續的方式生產綠色能源與高附加價值產物。其中，電催化反應被視為最具潛力實現此目標的策略，而電催化劑則在高效能量轉換過程中扮演關鍵角色。本研究旨在透過臨場(in situ) 及定點（identical location）穿透式電子顯微鏡觀測技術研究金屬單原子材料(零維)與金屬奈米線(一維)等電催化劑在生成過程與實際反應環境下的結構演變機制，進而為催化劑的設計提供優化與改良的指引。
首先，針對摻雜不同鉬前驅物含量的 Mo-ZIF-8 前驅體，分別在惰性、還原與氧化性氣氛下進行熱裂解，成功合成出鉬單原子、鉬奈米團簇、碳化鉬奈米顆粒以及金屬態鉬奈米顆粒鑲嵌於氮摻雜多孔碳基底上。其中，Mo-SA/PNC 催化劑展現優異的氮還原反應(nitrogen reduction reaction, NRR)效能，在-0.2 V（vs. RHE）的過電位下可達15.34 μg h-1 mg-1 的氨產率與24.03% 的法拉第效率。接著，我們利用臨場高解析度掃描穿透式電子顯微鏡觀察鐵單原子於低溫熱裂解階段的生成路徑。結合實驗結果與密度泛函理論計算，我們提出一個由Fe(acac)3 前驅物在 ZIF-8 骨架中分散性所主導的兩階段單原子形成機制。
此外，我們進一步擴展至雙金屬 Pt-Fe 系統，原子尺度下探討其在熱裂解過程中的熱穩定性與演變行為。臨場掃描穿透式電子顯微鏡觀測結果與非臨場的分析顯示，在雙金屬系統中，相鄰的鉑與鐵單原子可穩定存在超過1100 °C，顯示其對熱裂解的抵抗能力及鍵結強度明顯提升。
此外，我們開發出一種新穎的方法應用於定點穿透式電子顯微鏡觀測銥金屬奈米線於酸性工作環境下的結構變化。透過在金網上鍍覆一層鉑保護層，能夠有效抑制在長時間氧析出反應（oxygen evolution reaction, OER）過程中從金網溶解與再沉積的外來金屬汙染物。
在本研究中，我們透過先進的臨場與定點觀測技術揭示了電催化劑材料在原子尺度動態行為，不僅深化了對電催化劑演化機制的基礎理解，也為次世代多功能催化材料的設計提供重要方向與參考依據。

In light of escalating global energy consumption and the urgency of addressing climate change, researchers are actively seeking alternative strategies to generate green energy and valuable products through cleaner and more sustainable approaches. Electrocatalytic reactions have emerged as a promising solution toward this goal, with electrocatalysts playing a pivotal role in enabling efficient energy conversion. In this study, we focus on elucidating the structural evolution of electrocatalysts, specifically, single atom materials (zero-dimensional) and metal nanowires (one-dimensional), during both synthesis and operational conditions by employing in situ and identical location TEM techniques. This approach provides mechanistic insights that inform the rational design and optimization of advanced electrocatalysts.
To begin, Mo-ZIF-8 precursors with optimized molybdenum loadings were pyrolyzed under inert, reductive, and oxidative atmospheres, producing Mo single atoms (Mo-SAs), Mo nanoclusters (Mo-NCs), Mo2C nanoparticles (NPs), and metallic Mo NPs embedded within porous N-doped carbon. Among these, the Mo-SA/PNC catalyst demonstrated exceptional nitrogen reduction reaction (NRR) performance, achieving an NH3 yield of 15.34 μg h-1mg-1 and a Faradaic efficiency of 24.03% at an overpotential of -0.2 V vs. RHE. Subsequently, the formation pathway of Fe single atoms at low pyrolysis temperatures was elucidated via in situ high-resolution scanning transmission electron microscopy (HR-STEM). Based on these observations and supported by density functional theory (DFT) calculations, we propose a two-stage formation mechanism governed by the dispersibility of the Fe(acac)3 precursor within the ZIF-8 framework.
Moreover, we extended this investigation to a dual-metal Pt-Fe system to examine the thermal stability and atomic-scale evolution of Pt-Fe hetero-atomic pairs during pyrolysis. In situ STEM and post-pyrolysis analyses revealed that in the PF-ZIF system, adjacent Pt and Fe single atoms were retained up to 1100 °C, suggesting improved resistance to sintering and evaporation.
Additionally, we developed a novel approach to reveal the structural transformation of Ir nanowires under harsh acidic operating conditions using identical-location TEM (IL-TEM). By depositing Pt on the Au TEM grid as a protective layer, we effectively suppressed the undesired dissolution and redeposition of foreign species from Au grid during extended oxygen evolution reaction (OER) operation exceeding five hours.
Overall, by unveiling atomic-scale dynamics through advanced in situ- and IL-TEM techniques, this work provides deep mechanistic understanding of electrocatalyst evolution and offers valuable guidance for the design of next-generation multifunctional catalytic materials.