濺鍍MnCo應用於陰離子交換膜水電解陽極之性能、穩定性與碳酸化行為研究

Abstract

陰離子交換膜水電解系統具備非貴金屬觸媒與鹼性環境等優點，為具發展潛力之綠氫技術。然而，在KOH電解液中操作時，外界CO2可能進入系統並形成碳酸鹽或碳酸氫鹽物種，進而影響電解液組成、離子傳輸與電極界面狀態。因此，了解陽極於操作後之表面變化與碳酸化相關行為，對評估系統穩定性具有重要意義。 本研究以直流磁控濺鍍法將MnCo薄膜沉積於不鏽鋼纖維紙（SSP）上，作為AEMWE單堆電解水模組陽極，並以Ru/CP作為陰極，於1 M KOH電解液中進行模組測試。透過不同溫度、陰極乾濕式操作、加速應力測試（accelerated stress test, AST）及65 h定電流操作穩定性測試（long-term test, LT），評估MnCo/SSP之性能與穩定性；並結合SEM、EDS、XPS、XRD、UV-vis、ICP-MS及表面潤濕性觀察，分析操作後之界面與電解液物種變化。 結果顯示，MnCo/SSP陽極之AEMWE性能具有明顯溫度依賴性，於70 °C陰極濕式條件下可達約1 A/cm2等級之電流密度。穩定性操作中，經5000次AST動態循環測試後，極化曲線未出現明顯衰退；65 h LT測試下，模組電壓大致維持於1.78~1.82 V，顯示MnCo/SSP於本研究測試範圍內可維持穩定之電化學表現。 操作後材料分析顯示，AST後樣品表面出現較明顯之粗糙化、局部沉積與C、O 訊號富集，並伴隨較明顯之碳酸鹽相關殘留訊號；LT後樣品則呈現較均勻之表面變化。XPS結果顯示MnCo活性層於操作後發生表面化學態調整，UV-vis與ICP-MS分析亦顯示陽極側電解液中存在碳酸相關物種累積及少量含鉻物種增加。上述結果指出，MnCo/SSP陽極在AEMWE操作中雖可維持穩定電化學表現，但其界面仍會受到碳酸化、表面重構與局部電解液環境變化共同影響，其中動態負載條件下之界面變化較為明顯。

Anion exchange membrane water electrolysis offers advantages such as the use of non-precious-metal catalysts and operation under alkaline conditions, making it a promising technology for green hydrogen production. However, during operation in KOH electrolyte, CO₂ from the surrounding environment may enter the system and form carbonate or bicarbonate species, which can affect electrolyte composition, ion transport, and the electrode/electrolyte interfacial state. Therefore, understanding the post-operation surface changes and carbonation-related behavior of the anode is important for evaluating system stability. In this study, MnCo thin films were deposited on stainless-steel fiber paper by direct-current magnetron sputtering and used as the anode in an AEMWE single cell, with Ru/CP used as the cathode. The cell was operated in 1 M KOH electrolyte. The performance and stability of MnCo/SSP were evaluated under different temperatures, cathode dry/wet operating conditions, accelerated stress testing, and a 65 h constant-current test. Post-operation interfacial changes and electrolyte species variation were further analyzed using SEM, EDS, XPS, XRD, UV-vis, ICP-MS, and surface wettability observation. The results show that the AEMWE performance of the MnCo/SSP anode exhibits clear temperature dependence. Under cathode-wet operation at 70 °C, the current density reached the level of approximately 1 A/cm2. In the stability tests, no obvious degradation in the polarization curves was observed after 5000 accelerated stress test (AST) dynamic cycles. During the 65 h long-term (LT) test, the cell voltage remained approximately within 1.78~1.82 V, indicating that MnCo/SSP maintained stable electrochemical performance within the testing window of this study. Post-operation material analysis revealed that the AST-treated sample exhibited more pronounced surface roughening, localized deposits, and enrichment of C and O signals, accompanied by more evident carbonate-related residue signals. In contrast, the LT-treated sample showed a more uniform surface evolution. XPS results indicated that the MnCo active layer underwent surface chemical-state changes after operation. UV-vis and ICP-MS analyses further suggested the accumulation of carbonate-related species and a slight increase in Cr-containing species in the anolyte. These results indicate that although the MnCo/SSP anode maintained stable electrochemical performance during AEMWE operation, its interface was still affected by carbonation, surface reconstruction, and local changes in the electrolyte environment, with more pronounced interfacial changes under dynamic-load operation.