📄 本實驗室論文

Surface Electroactive Sites of Tungstated Zirconia Catalysts for Vanadium Redox Flow Batteries

鎢酸化鋯觸媒之表面電活性位點應用於釩氧化還原液流電池

ACS Applied Materials & Interfaces 2024, 16, 7047–7056 (ACS Publications) | DOI: 10.1021/acsami.3c14633

作者：Aknachew Mebreku Demeku, Daniel Manaye Kabtamu*, Guan-Cheng Chen, Yun-Ting Ou, Zih-Jhong Huang, Tai-Chin Chiang, Hsin-Chih Huang, and Chen-Hao Wang*

📄 英文摘要

Surface electroactive sites for tungstate zirconia (WZ) were created by utilizing tungstate-immobilized UiO-66 as precursors via a double-solvent impregnation method under a mild calcination temperature. The WZ-22-650 catalyst, containing a moderate W content (22%), demonstrated a high density of surface electroactive sites. Proper heat treatment facilitated the binding of oligomeric tungsten clusters to stabilized tetragonal ZrO2, resulting in improved catalytic performance toward the VO2+/VO2+ redox couples compared to other tested samples. The substantial surface area, mesoporous structure, and establishment of new W-O-Zr bonds affirm the firm anchoring of WOx to ZrO2. This robust attachment enhances surface electroactive sites, elevating the electrochemical performance of vanadium redox flow batteries (VRFBs). Charge-discharge tests further demonstrate that the superior voltage efficiency (VE) and energy efficiency (EE) for VRFBs using the WZ-22-650 catalyst are 87.76 and 83.94% at 80 mA cm-2, which are 13.42% VE and 10.88% EE better than heat-treated graphite felt, respectively. Even at a higher current density of 160 mA cm-2, VRFBs utilizing the WZ-22-650 catalyst maintained considerable efficiency, recording VE and EE values of 76.76 and 74.86%, respectively. This facile synthesis method resulted in WZ catalysts displaying superior catalytic activity and excellent cyclability, offering a promising avenue for the development of metal-oxide-based catalysts.

📄 中文摘要

本研究以鎢酸鹽固定化的 UiO-66 為前驅體，採用雙溶劑浸漬法並在溫和退火溫度下，構築鎢酸化鋯（WZ）觸媒的表面電活性位點。含適量鎢含量（22%）的 WZ-22-650 觸媒展現高密度的表面電活性位點。適當的熱處理促進了寡聚鎢團簇與穩定四方晶 ZrO2 的鍵結，使其對 VO2+/VO2+ 氧化還原對的催化性能優於其他測試樣品。大的比表面積、介孔結構以及新 W-O-Zr 鍵的形成，確認了 WOx 與 ZrO2 之間的牢固錨定。這種強健的鍵結增強了表面電活性位點，提升了釩氧化還原液流電池（VRFB）的電化學性能。充放電測試進一步證明，使用 WZ-22-650 觸媒的 VRFB 在 80 mA/cm² 下之電壓效率（VE）與能量效率（EE）分別達到 87.76% 與 83.94%，較熱處理石墨氈分別提升 13.42% VE 與 10.88% EE。即使在較高電流密度 160 mA/cm² 下，VRFB 仍維持良好效率，VE 與 EE 分別為 76.76% 與 74.86%。這種簡便的合成方法使 WZ 觸媒展現優異的催化活性與循環穩定性，為金屬氧化物觸媒的開發提供了具前景的方向。

🔬 五項核心重要發現

首創以 MOF 前驅體（UiO-66）合成 WZ 觸媒：採用雙溶劑浸漬法，成功將 WOx 錨定於 ZrO2 上形成 W-O-Zr 鍵。

WZ-22-650（22% W）為最佳組成，展現最高表面電活性位點密度與電催化性能。

87.76% VE 與 83.94% EE @ 80 mA/cm²，較熱處理石墨氈分別提升 13.42% 與 10.88%。

高電流穩定性：在 160 mA/cm² 下仍維持 76.76% VE 與 74.86% EE。

優異循環穩定性：WZ-22-650 觸媒展現良好的循環耐久性，為金屬氧化物觸媒的開發提供新方向。

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