In Situ Modulated Nickel Single Atoms on Bicontinuous Porous Carbon Fibers and Sheets Networks for Acidic CO Reduction.

Carbon-supported single-atom catalysts exhibit exceptional properties in acidic CO reduction. However, traditional carbon supports fall short in building high-site-utilization and CO-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 CO transport. Such unique features enable enhanced Ni utilization and local CO 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-N to an out-of-plane configuration with expanded Ni-N bond during operating CO electroreduction. The potential-driven low-valance-state Ni-N possesses enhanced intrinsic electrokinetics for CO 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, a TOF of 55.5 s, and a SPCE of 89.2% in acidic CO-to-CO electrolysis.