Ni Nanoclusters Anchored on Ni-N-C Sites for CO₂ Electroreduction at High Current Densities

Transition metal catalyst-based electrocatalytic CO₂ reduction is a highly attractive approach to fulfill the renewable energy storage and a negative carbon cycle. However, it remains a great challenge for the earth-abundant VIII transition metal catalysts to achieve highly selective, active, and stable CO₂ electroreduction. Herein, bamboo-like carbon nanotubes that anchor both Ni nanoclusters and atomically dispersed Ni-N-C sites (NiNCNT) are developed for exclusive CO₂ conversion to CO at stable industry-relevant current densities. Through optimization of gas-liquid-catalyst interphases via hydrophobic modulation, NiNCNT exhibits as high as Faradaic efficiency (FE) of 99.3% for CO formation at a current density of -300 mA·cm^-2 (-0.35 V vs reversible hydrogen electrode (RHE)), and even an extremely high CO partial current density (j_CO) of -457 mA·cm^-2 corresponding to a CO FE of 91.4% at -0.48 V vs RHE. Such superior CO₂ electroreduction performance is ascribed to the enhanced electron transfer and local electron density of Ni 3d orbitals upon incorporation of Ni nanoclusters, which facilitates the formation of the COOH* intermediate.