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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非常规晶粒破碎创造了高密度边界，可在安培级电流密度下实现高效的 CO2 到 C2+ 电转化


电催化二氧化碳还原反应（CO2RR）生产多碳产品（C2+）是实现净零碳排放的最可持续的方式之一。在许多方法中，富集铜 (Cu) 催化剂中的晶界 (GB) 已被证明可以提高 C2+ 的产量。然而，它仍然缺乏有效的策略来可控地合成丰富的 GB，这使得高效的 C2+ 生产成为一个持续的挑战，特别是在安培级电流密度下。在此，我们提出了一种新颖的策略，可以在热退火过程中实现非常规的晶粒破碎，从而产生可控的晶界密度。具有最大 GB 密度的催化剂表现出约 100% 的峰值 C2+ 法拉第效率。 H 型池为 70.0 %，流通池为 68.2 %；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相结合表明，GBs的富集产生了更多的活性位点，从而获得了更高的*CO覆盖率，从而促进了*CO-*CO偶联过程并最终实现了高C2+生产性能。