In-situ construction of iron-modified nickel nanoparticles assisted by hexamethylenetetramine with the internal and external collaboration for highly selective electrocatalytic carbon dioxide reduction.

Carbon dioxide (CO) electroreduction provides a sustainable route for realizing carbon neutrality and energy supply. Up to now, challenges remain in employing abundant and inexpensive nickel materials as candidates for CO reduction due to their low activity and favorable hydrogen evolution. Here, the representative iron-modified nickel nanoparticles embedded in nitrogen-doped carbon (Ni-Fe-NC) with the porous botryoid morphology were successfully developed. Hexamethylenetetramine is used as nitrogen-doped carbon source. The collaboration of internal lattice expansion with electron effect and external confinement effect with size effect endows the significant enhancement in electrocatalytic CO reduction. The optimized Ni-Fe-NC exhibits broad potential ranges for continuous carbon monoxide (CO) production. A superb CO Faradaic efficiency (FE) of 85.0 % realized at -1.1 V maintains a longtime durability over 35 h, which exceeds many state-of-the-art metal catalysts. Theoretical calculations further confirm that electron redistribution promotes the desorption of CO in the process for favorable CO production. This work opens a new avenue to design efficient nickel-based materials by considering the intrinsic structure and external confinement for CO reduction.