Synthesis of high-loading atomic-level dispersed catalysts for highly efficient electrochemical CO₂ reduction reaction (eCO₂RR) to ethylene (C₂H₄) in neutral electrolyte remain challenging tasks. To address common aggregation issues, a host-guest strategy is employed, by using a metal-azolate framework (MAF-4) with nanocages as the host and a dinuclear Cu(I) complex as the guest, to form precursors for pyrolysis into a series of nitrogen-doped porous carbons (NPCs) with varying loadings of dual copper sites, namely NPC_MAF-4-Cu₂-21 (21.2 wt%), NPC_MAF-4-Cu₂-11 (10.6 wt%), and NPC_MAF-4-Cu₂-7 (6.9 wt%). Interestingly, as the loading of dual copper sites increased from 6.9 to 21.2 wt%, the partial current density for eCO₂RR to yield C₂H₄ also gradually increased from 38.7 to 93.6 mA cm⁻². In a 0.1 m KHCO₃ electrolyte, at −1.4 V versus reversible hydrogen electrode (vs. RHE), NPC_MAF-4-Cu₂-21 exhibits the excellent performance with a Faradaic efficiency of 52% and a current density of 180 mA cm⁻². Such performance can be attributed to the presence of ultrahigh-loading dual copper sites, which promotes C─C coupling and the formation of C₂ products. The findings demonstrate the confinement effect of MAF-4 with nanocages is conducive to the preparation of high-loading atomic-level catalysts.

中文翻译：

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在氮掺杂多孔碳中制备超高负载双铜位点，促进中性条件下 CO2 电还原为 C2H4


在中性电解质中合成用于高效电化学 CO₂ 还原反应 （eCO₂RR） 与乙烯 （C₂H₄） 的高负载原子级分散催化剂仍然是一项具有挑战性的任务。为了解决常见的聚集问题，采用主客体策略，使用以纳米笼为主体、以二核 Cu（I） 配合物为客体的金属偶氮酸盐框架 （MAF-4），形成前驱体热解成一系列具有不同负载的双铜位点的氮掺杂多孔碳 （NPC），即 NPC_{MAF-4-Cu 2-21} （21.2 wt%）， NPC_{MAF-4-Cu 2-11} （10.6 wt%） 和 NPC_{MAF-4-Cu 2-7} （6.9 wt%）。有趣的是，随着双铜位点的负载从 6.9 wt% 增加到 21.2 wt%，产生 C₂H₄ 的 eCO₂RR 的部分电流密度也逐渐从 38.7 增加到 93.6 mA ^cm-2。在 0.1 m KHCO₃ 电解质中，在 -1.4 V 下与可逆氢电极（相比。RHE） 中，NPC_{MAF-4-Cu 2-21} 表现出优异的性能，法拉第效率为 52%，电流密度为 180 mA ^cm-2。这种性能可归因于超高负载双铜位点的存在，它促进了 C─C 偶联和 C₂ 产物的形成。研究结果表明，MAF-4 与纳米笼的约束效应有利于制备高负载原子级催化剂。