Carbon‐supported single‐atom catalysts exhibit exceptional properties in acidic CO2 reduction. However, traditional carbon supports fall short in building high‐site‐utilization and CO2‐rich interfacial environments, and the structural evolution of single‐atom metals and catalytic mechanisms under realistic conditions remain ambiguous. Herein, an interconnected mesoporous carbon nanofiber and carbon nanosheet network (IPCF@CS) is reported, derived from microphase‐separated block copolymer, to improve catalytic efficiency of isolated Ni. In IPCF@CS nanostructure, highly mesoporous IPCF hinders stacking of CS that provides additional fully exposed sites and abundant bicontinuous mesochannels of IPCF facilitate smooth CO2 transport. Such unique features enable enhanced Ni utilization and local CO2 enrichment, which cannot be achieved over conventional pore‐deficient and discontinuous porous carbon fibers‐based supports. In situ X‐ray and Infrared spectroscopy coupling constant‐potential calculations reveal the dynamic distortion of the planar Ni−N4 to an out‐of‐plane configuration with expanded Ni−N bond during operating CO2 electroreduction. The potential‐driven low‐valance‐state Ni−N4 possesses enhanced intrinsic electrokinetics for CO2 activation and CO desorption yet inhibiting hydrogen evolution. The favorable electronic and interfacial reaction environments, resulted from the in situ tailored Ni site and IPCF@CS support, achieve an FE of near 100% at 540 mA cm−2, a TOF of 55.5 s−1, and a SPCE of 89.2% in acidic CO2‐to‐CO electrolysis.

中文翻译：

---

双连续多孔碳纤维和片状网络上的原位调制镍单原子用于酸性 CO2 还原


碳负载型单原子催化剂在酸性 CO2 还原方面表现出优异的性能。然而，传统的碳载体在构建高位利用率和富含 CO2 的界面环境方面存在不足，并且在现实条件下单原子金属的结构演变和催化机制仍然不明确。在此，报道了一种互连的介孔碳纳米纤维和碳纳米片网络 （IPCF@CS），源自微相分离的嵌段共聚物，以提高孤立的 Ni 的催化效率。在IPCF@CS纳米结构中，高度介孔的 IPCF 阻碍了 CS 的堆积，从而提供了额外的完全暴露位点，而 IPCF 丰富的双连续介通道有助于 CO2 的顺利传输。这种独特的功能可以提高镍的利用率和局部 CO2 富集，这是传统的缺孔和不连续多孔碳纤维载体无法实现的。原位 X 射线和红外光谱耦合恒电位计算揭示了在操作 CO2 电还原过程中，平面 Ni-N4 的动态变形为具有膨胀 Ni-N 键的面外构型。电位驱动的低价态 Ni-N4 具有增强的 CO2 活化和 CO 解吸的内禀电动力学，但抑制析氢。由原位定制的 Ni 位点和IPCF@CS支持产生的有利电子和界面反应环境在 540 mA cm-2 时实现了接近 100% 的 FE，TOF 为 55.5 s-1，在酸性 CO2 到 CO 电解中实现了 89.2% 的 SPCE。