N-doped ordered mesoporous carbon embedded with Ni-N₃-Pyr sites achieve nearly 100% selectivity for CO₂RR to CO

Transition metal-nitrogen-carbon (M-N-C) catalysts show great promise for converting CO₂ into valuable fuels and chemicals via electroreduction (CO₂RR). Nonetheless, controversy remains regarding which specific MNₓ coordination structure in M-N-C catalysts governs CO₂RR performance. We synthesized a series of Ni-NOMC catalysts with high specific surface area and varying NiN₃-Pyr site loadings using SBA-15 as a template, employing a small molecule condensation and pyrolysis strategy. Aberration-corrected scanning transmission electron microscopy (AC-STEM) and X-ray absorption spectroscopy (XAS) confirmed the presence of atomically dispersed Ni sites coordinated by pyrrolic nitrogen (NiN₃-Pyr). The Ni-NOMC-3 catalyst, with a higher NiN 3 -Pyr loading, achieved a remarkable CO Faraday efficiency (FE CO ) of 99.6% at −0.57 V vs. the reversible hydrogen electrode (RHE), while maintaining FE CO > 99% across a broad potential window (−0.17 to −0.97 V vs. RHE). Moreover, the ordered mesoporous structure of this catalyst enhances mass transport properties and optimizes active site accessibility, enabling a high CO partial current density of 157 mA·cm⁻² in a flow cell system. Theoretical simulations further reveal that the NiN₃-Pyr coordination structure exhibits superior catalytic performance for CO₂RR-to-CO compared to other possible NiN x configurations.