Long-term electrocatalytic N2 fixation by MOF-derived Y-stabilized ZrO2: An insight into deactivation mechanism
writer：Shijian Luo, Xiaoman Li, Mingyuan Wang, Xu Zhang, Wanguo Gao, Sen-Da Su, Guiwu Liu and Min Luo
keywords：MOF-derived Y-stabilized ZrO2
source：期刊
specific source：Journal of Materials Chemistry A（JMCA）
Issue time：2020年
成果簡介：
電催化固氮中的催化活性中心是什么？一些催化劑經過長時間反應后發生了失活作用，失活機制到底是什么？這些問題一直困擾著電催化固氮研究。為了深入探究這一問題，我們在實驗中合成金屬有機框架材料衍生的ZrO2/C復合催化劑，發現長時間反應3天后催化活性完全消失了。通過DFT理論計算，表明材料中氧空位并不穩定，來自水溶液中含氧離子會不斷填充不穩定的氧空位，最終導致催化劑失活。進而我們通過原位摻雜Y制備了Y-ZrO2,發現低價雜質原子的摻雜穩定了材料中的氧空位，在長達7天的催化實驗中催化活性僅下降了10%不到。為了進一步驗證氧空位的填充情況，通過納克級質量敏感的電化學石英晶體微天平（EQCM）原位測試研究證明了在這兩種催化劑中氧空位的穩定性差異是造成其催化壽命懸殊的直接原因。這一研究結果為室溫常壓固氮電催化劑的設計提供了理論依據和設計原則。該成果“Long-term electrocatalytic N2 fixation by MOF-derived Y-stabilized ZrO2: An insight into deactivation mechanism”在線發表在JMCA期刊。
Abstract: Industrially, NH3 synthesis largely dependent on the Haber-Bosch method which consumes a lot of energy and emits huge CO2. Recently, Electrochemical N2 reduction reaction (NRR) has been recognized as a promising method to achieve clean and sustainable NH3 production, thus the high-efficient and durable catalysts are urgently desired. In this paper, we report a MOF-derived carbon/Y-stabilized ZrO2 nanocomposite (C@YSZ) works as an efficien telectrocatalyst for NRR in 0.1 M Na2SO4. It achieves a large NH3 production of 24.6 μg h-1 mg-1cat. and a high Faradaic efficiency of 8.2% at -0.5 V vs. reversible hydrogen electrode. Experimental results demonstrate the surface oxygen vacancies are the main catalytic sites for NRR. Introducing of Y3+ into ZrO2 lattice has significant effect to increase and stabilize the O-vacancies. Meanwhile, this catalyst displays remarkable stability and durability for NRR performance, showing a negligible change after 7 days reaction, better than most reported NRR electrocatalysts. Moreover, in-situ electrochemical quartz-crystal microbalance (EQCM) was firstly applied in NRR field and successfully combined with density functional theory (DFT) calculations to reveal the deactivation mechanism.
文章鏈接：
https://doi.org/10.1039/D0TA01154A