Electrocatalytic CO2 reduction reaction (CO2RR) to produce multi-carbon products (C2+) is one of the most sustainable manners to achieve net-zero carbon emissions. Among many approaches, enriching grain boundaries (GBs) in copper (Cu) catalysts has been demonstrated to enable enhancement for C2+ production. However, it still lacks effective strategies to controllably synthesize abundant GBs, rendering efficient C2+ production a persistent challenge, especially at ampere-level current density. Herein, we propose a novel strategy, which can achieve unconventional grain fragmentation during thermal annealing and thus create controllable GB densities. The catalyst with the utmost GB density exhibits a peak C2+ faradaic efficiency of ca. 70.0 % in H-type cell and 68.2 % in flow cell; even more impressively, it delivers an ultra-high C2+ current density of 0.768 A cm−2, outperforming most recently reported results. A combination of in situ spectroscopies and theoretical calculations reveal that the enrichment of GBs yields more active sites for a higher *CO coverage, leading to promotion of the *CO-*CO coupling process and ultimately high C2+ production performance.

中文翻译：

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非常规晶粒碎裂为安培级电流密度的高效 CO2 到 C2+ 电转换创造了高密度边界


电催化 CO2 还原反应 （CO2RR） 生产多碳产品 （C2+） 是实现净零碳排放的最可持续方式之一。在众多方法中，在铜 （Cu） 催化剂中富集晶界 （GB） 已被证明可以提高 C2+ 的产量。然而，它仍然缺乏可控合成丰富 GB 的有效策略，这使得高效的 C2+ 生产成为一个持续的挑战，尤其是在安培级电流密度下。在此，我们提出了一种新的策略，可以在热退火过程中实现非常规的晶粒碎裂，从而产生可控的 GB 密度。具有最大 GB 密度的催化剂在 H 型池中表现出约 70.0 % 的峰值 C2+ 法拉第效率，在流通池中表现出约 68.2% 的峰值法拉第效率;更令人印象深刻的是，它提供了 0.768 A cm-2 的超高 C2+ 电流密度，优于最近报道的结果。原位光谱和理论计算的结合表明，GB 的富集会产生更多的活性位点，从而获得更高的 *CO 覆盖率，从而促进 *CO-*CO 偶联过程，并最终实现高 C2+ 生产性能。