基板誘導之鎳鉬氧化物奈米線電子調控於陰離子交換膜水電解析氧反應之研究

Abstract

陰離子交換膜水電解 (anion exchange membrane water electrolysis, AEMWE) 系統中，設計兼具高活性與長期穩定性的陽極材料仍為關鍵挑戰之一。其中，催化劑層 (catalyst layer, CL) 與多孔傳輸層 (porous transport layer, PTL) 的界面整合，對於電荷傳輸效率、界面電阻以及操作穩定性具決定性影響。因此，如何透過材料與結構設計優化CL/PTL界面耦合，成為提升AEMWE性能的重要研究方向。本研究採用水熱法於不同導電基板上原位成長NiMoO4奈米線，以碳紙 (carbon paper, CP)、不鏽鋼纖維紙 (stainless steel fiber paper, SSP) 及鎳纖維紙 (nickel fiber paper, NFP) 導電基板作為多孔傳輸層，製備無黏結劑之整合型CL/PTL電極。此結構不僅可避免傳統催化層中黏結劑引入之界面阻抗，同時提升電極導電性與機械穩定性。實驗結果表明，相較於CP與NFP基板，SSP提供了更有利的界面化學與電子結構環境。在水熱成長過程中，SSP中Fe元素的溶出與引入，促進NiMoO4奈米線的Ni3+比例，並有效調控氧缺陷濃度，同時維持Mo5+/Mo6+之適當比例，進而提升析氧反應 (oxygen evolution reaction, OER) 之催化活性。在AEMWE模組測試中，於70 °C且陰極濕式操作條件下，NiMoO4/SSP電極在2.0 V下達2.67 A cm-2之高電流密度；在陰極乾式 (Cathode-dry) 仍可維持1.83 A cm-2，顯著優於NiMoO4/CP與NiMoO4/NFP電極。60小時長時間測試電壓僅輕微上升，展現良好的操作穩定性。進一步的結構與表面分析結果指出，在長時間模組操作過程中Mo發生部分浸出，並誘發NiMoO4表面自發重構為具有高OER活性的γ-NiOOH相，此轉變被認為是提升長期催化性能的重要機制之一。總而言之，本研究證實透過基板工程 (substrate engineering) 策略，結合界面耦合強化與基板衍生元素摻雜效應，能有效提升AEMWE陽極之電催化性能與耐久性，為未來高效且穩定之水電解系統設計提供具體方向。

In anion exchange membrane water electrolysis (AEMWE), developing anodic materials with both high activity and long-term durability remains a key challenge, where the catalyst layer/porous transport layer (CL/PTL) interface critically governs charge transfer and stability. Herein, NiMoO4 nanowires were directly grown on carbon paper (CP), stainless steel fiber paper (SSP), and nickel fiber paper (NFP) via a hydrothermal method to construct binder-free integrated CL/PTL electrodes. This design eliminates binder-induced resistance and mechanical degradation, while enhancing conductivity and structural integrity. Among the substrates, SSP provides the most favorable interfacial environment. Fe species introduced during growth modulate the electronic structure of NiMoO4, increasing Ni3+ content, regulating oxygen vacancies, and maintaining a balanced Mo5+/Mo6+ ratio, thereby enhancing oxygen evolution reaction (OER) activity. In AEMWE testing, NiMoO₄/SSP achieves 2.67 A cm-2 at 2.0 V under wet cathode conditions at 70 °C and retains 1.83 A cm-2 under dry operation, outperforming CP and NFP counterparts. The system also exhibits stable operation over 60 h with minimal voltage increase. Post-analysis reveals partial Mo leaching and in situ reconstruction into an active γ-NiOOH phase, which contributes to sustained catalytic performance. Overall, this work highlights substrate engineering as an effective strategy to enhance both the activity and durability of AEMWE anodes by integrating interfacial coupling with substrate-induced modulation.