We synthesized Cu single atoms embedded in a N-doped porous carbon catalyst with a high Faradaic efficiency of 93.5% at −0.50 V (vs. RHE) for CO₂ reduction to CO. The evolution of Cu single-atom sites to nanoclusters of about 1 nm was observed after CO₂ reduction at a potential lower than −0.30 V (vs. RHE). The DFT calculation indicates that Cu nanoclusters improve the CO₂ activation and the adsorption of intermediate *COOH, thus exhibiting higher catalytic activity than CuN_x sites. The structural instability observed in this study helps in understanding the actual active sites of Cu single atom catalysts for CO₂ reduction.

中文翻译：

---

在 CO2 还原为 CO 过程中 Cu 单原子催化剂向纳米团簇的演变

我们合成了嵌入 N 掺杂多孔碳催化剂中的 Cu 单原子，在 -0.50 V（与RHE 相比）下，将 CO ₂还原为 CO 的法拉第效率高达 93.5%。Cu 单原子位点向纳米团簇的演变约为在低于 -0.30 V 的电势下CO ₂还原后观察到 1 nm （相对于RHE）。DFT计算表明Cu纳米团簇提高了CO ₂活化和中间体*COOH的吸附，因此表现出比CuN _x位点更高的催化活性。本研究中观察到的结构不稳定性有助于了解用于 CO ₂还原的 Cu 单原子催化剂的实际活性位点。