Structural Reconstruction of Ce-MOF with Active Sites for Efficient Electrocatalytic N2 Reduction
Structural Reconstruction of Ce-MOF with Active Sites for Efficient Electrocatalytic N2 Reduction
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DOI：
10.1021/acsaem.1c01656
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发表时间：
2021-10
影响因子：
6.4
通讯作者：
Peixin Liu;P. Jing;Xuang-Long Xu;Baocang Liu;Jun Zhang
中科院分区：
文献类型：
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作者：
Peixin Liu;P. Jing;Xuang-Long Xu;Baocang Liu;Jun Zhang
在温和条件下由氮气电合成氨是一种很有前途的替代耗能的Haber-Bosch工艺。金属有机骨架(MOF)是一种很有前途的N_2还原反应电催化剂，但它们大多对非理想的、竞争性的析氢反应具有催化活性。在此，我们开发了一种在铜网衬底上生长Ce-MOF的简便方法。与可逆氢电极相比，具有自支撑结构的Ce-MOF可以直接作为N2还原反应的电极，表现出高效的电催化性能，与可逆氢电极相比，在−0.2V时，NH3的产率为14.83kgh-1 cm-2，法拉第效率为10.81%。电催化后的Ce-MOF的结构表征表明，作为预催化剂的Ce-MOF在负电位下进行了结构重构，生成了具有催化活性的CeO2，氧空位嵌入在无定形的Ce-MOF中。此外，Ce-MOF在多孔导电铜网上原位生长形成的自支撑结构赋予了电催化剂更高的稳定性、导电性和传质性能。本工作揭示了Ce-MOF在电催化过程中的结构变化，为合理设计MOF基电催化剂提供了新的思路。
The electrochemical synthesis of ammonia from N2under mild conditions is a promising alternative to the energy-consuming Haber–Bosch process. Metal–organic frameworks (MOFs) are promising electrocatalysts for the N2reduction reaction, but most of them are active for the undesirable and competitive hydrogen evolution reaction. Herein, we developed a facile strategy to grow a Ce-MOF on copper mesh substrate. The Ce-MOF with a self-supporting structure could be directly used as an electrode for the N2reduction reaction, demonstrating highly efficient electrocatalytic performance with an NH3yield of 14.83 μg h–1cm–2and a Faradaic efficiency of 10.81% at −0.2 V versus a reversible hydrogen electrode. Structural characterizations of Ce-MOF after electrocatalysis revealed that Ce-MOF as precatalyst underwent structural reconstruction at negative potential, forming catalytically active CeO2with oxygen vacancies embedded in the amorphous Ce-MOF. In addition, the self-supporting structure formed by in situ growth of Ce-MOF on porous and conductive cooper mesh endowed the electrocatalyst with enhanced stability, conductivity, and mass transport. This work demonstrated the structural transformation of Ce-MOF during the electrocatalytic process and provided new insight for the rational design of MOF-based electrocatalysts.