Engineering Ag-N Single-Atom Sites on Porous Concave N-Doped Carbon for Boosting CO₂ Electroreduction

The electrochemical CO₂ reduction reaction (CO₂RR) offers an environmentally benign pathway for renewable energy conversion and further regulation of the environmental CO₂ concentration to achieve carbon cycling. However, developing desired electrocatalysts with high CO Faradaic efficiency (FE_CO) at an ultralow overpotential remains a grand challenge. Herein, we report an effective CO₂RR electrocatalyst that features Ag single-atom coordinated with three nitrogen atoms (Ag₁-N₃) anchored on porous concave N-doped carbon (Ag₁-N₃/PCNC), which is identified by X-ray absorption spectroscopy. Ag₁-N₃/PCNC shows a low CO₂RR onset potential of -0.24 V, high maximum FE_CO of 95% at -0.37 V, and high CO partial current density of 7.6 mA cm^-2 at -0.55 V, exceeding most of the previous Ag electrocatalysts. The in situ infrared absorption spectra technique proves that Ag₁-N₃ single-atom sites have sole linear-adsorbed CO and can easily desorb *CO species to achieve the highest CO selectivity in comparison with the corresponding counterparts. This work provides significant inspiration on boosting CO₂RR by tuning the active center at an atomic level to achieve a specific absorption with an intermediate.