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

成果简介：   

       电催化固氮中的催化活性中心是什么？一些催化剂经过长时间反应后发生了失活作用，失活机制到底是什么？这些问题一直困扰着电催化固氮研究。为了深入探究这一问题，我们在实验中合成金属有机框架材料衍生的ZrO2/C复合催化剂，发现长时间反应3天后催化活性完全消失了。通过DFT理论计算，表明材料中氧空位并不稳定，来自水溶液中含氧离子会不断填充不稳定的氧空位，最终导致催化剂失活。进而我们通过原位掺杂Y制备了Y-ZrO2,发现低价杂质原子的掺杂稳定了材料中的氧空位，在长达7天的催化实验中催化活性仅下降了10%不到。为了进一步验证氧空位的填充情况，通过纳克级质量敏感的电化学石英晶体微天平（EQCM）原位测试研究证明了在这两种催化剂中氧空位的稳定性差异是造成其催化寿命悬殊的直接原因。这一研究结果为室温常压固氮电催化剂的设计提供了理论依据和设计原则。该成果“Long-term electrocatalytic N2 fixation by MOF-derived Y-stabilized ZrO2: An insight into deactivation mechanism”在线发表在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.

文章链接：

https://doi.org/10.1039/D0TA01154A