Liu Yiwen, Meng Xianbin, Zhao Zhiqiang, Li Kai, Lin Yuqing
Department of Chemistry, Capital Normal University, Beijing 100048, China.
Nanomaterials (Basel). 2022 Aug 27;12(17):2964. doi: 10.3390/nano12172964.
The electrocatalytic nitrogen reduction reaction (NRR) can use renewable electricity to convert water and N into NH under normal temperature and pressure conditions. However, due to the competitiveness of the hydrogen evolution reaction (HER), the ammonia production rate (R) and Faraday efficiency (FE) of NRR catalysts cannot meet the needs of large-scale industrialization. Herein, by assembling hydrophobic ZIF-8 on a cerium oxide (CeO) nanorod, we designed an excellent electrocatalyst CeO-ZIF-8 with intrinsic NRR activity. The hydrophobic ZIF-8 surface was conducive to the efficient three-phase contact point of N (gas), CeO (solid) and electrolyte (liquid). Therefore, N is concentrated and H is deconcentrated on the CeO-ZIF-8 electrocatalyst surface, which improves NRR and suppresses HER and finally CeO-ZIF-8 exhibits excellent NRR performance with an R of 2.12 μg h cm and FE of 8.41% at -0.50 V (vs. RHE). It is worth noting that CeO-ZIF-8 showed excellent stability in the six-cycle test, and the R and FE variation were negligible. This study paves a route for inhibiting the competitive reaction to improve the NRR catalyst activity and may provide a new strategy for NRR catalyst design.
电催化氮还原反应（NRR）能够在常温常压条件下利用可再生电力将水和氮气转化为氨。然而，由于析氢反应（HER）的竞争性，NRR催化剂的产氨速率（R）和法拉第效率（FE）无法满足大规模工业化的需求。在此，通过将疏水性的ZIF-8组装在氧化铈（CeO）纳米棒上，我们设计了一种具有本征NRR活性的优异电催化剂CeO-ZIF-8。疏水性的ZIF-8表面有利于氮气（气体）、CeO（固体）和电解质（液体）形成高效的三相接触点。因此，氮气在CeO-ZIF-8电催化剂表面富集，氢气解富集，这提高了NRR并抑制了HER，最终CeO-ZIF-8在-0.50 V（相对于可逆氢电极，RHE）时表现出优异的NRR性能，产氨速率为2.12 μg h cm，法拉第效率为8.41%。值得注意的是，CeO-ZIF-8在六次循环测试中表现出优异的稳定性，产氨速率和法拉第效率的变化可忽略不计。本研究为抑制竞争反应以提高NRR催化剂活性开辟了一条途径，并可能为NRR催化剂设计提供新策略。
