Engineering Ag–N_x 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.