Transforming CO Poisoning into a Critical Step for Electrocatalytic C─N Coupling to Urea in a Carbon-Dot-Dominated Nanoreactor.

Modern catalysis science has traditionally viewed carbon monoxide (CO) poisoning negatively due to its detrimental effects, such as the deactivation of metal sites. Here, we demonstrate a transformative approach by converting CO poisoning into a beneficial strategy to achieve high activity and selectivity in urea electrosynthesis. We designed a multiscale and multisite nanoreactor composed of copper-carbon dots (Cu-CDs) and bornite (Cu5FeS4), which exploits CO-poisoned iron sites as anchors to facilitate efficient multi-species integration. This nanoreactor configuration delivers an unprecedented Curea - selectivity of 100%, a high urea yield rate of 1131.84 µg h-1 mgcat -1 and a Faradaic efficiency of 42.35% at an ultra-low potential. Consequently, the catalyst achieves exceptional dual benefits of a high yield rate and low energy consumption of 31.18 kWh kgurea -1, outperforming all previously reported earth-abundant electrocatalysts. Mechanistic studies and theoretical calculations reveal that the strong interaction between Fe and *CO, coupled with spatially separated yet adjacent Fe, Cu1, and Cu2 sites, enables stepwise conversion from *CO to *CONH2 and subsequently to *CO(NH2)2 within the nano-confined space dominated by Cu-CDs. This work provides a groundbreaking catalyst design strategy by effectively harnessing CO poisoning for enhanced electrocatalytic performance.