Asymmetric Coordination Induces Electron Localization at Ca Sites for Robust CO₂ Electroreduction to CO

Area of Science:

• Electrochemistry
• Catalysis
• Materials Science

Background:

• Single-atom catalysts (SACs) show promise for CO₂ electroreduction.
• Delocalized orbitals in SACs hinder CO₂ activation to *COOH.
• Preventing hydrogen evolution and CO poisoning are key challenges.

Purpose of the Study:

• To develop a strategy for enhancing CO₂ activation in main group SACs.
• To improve the catalytic performance for CO₂ electroreduction to CO.
• To investigate the role of oxygen doping and asymmetric coordination.

Main Methods:

• Theoretical calculations (e.g., DFT) to understand electronic structure and reaction mechanisms.
• X-ray absorption fine spectroscopy (XAFS) for characterizing the catalyst's coordination environment.
• In situ attenuated total reflection infrared spectroscopy (ATR-IR) to monitor reaction intermediates.

Main Results:

• An oxygen-doped calcium SAC with asymmetric N₃O coordination (Ca-N₃O) was synthesized.
• Ca-N₃O demonstrated enhanced electron localization, promoting *COOH formation.
• The catalyst achieved a turnover frequency of ~15,000 h⁻¹ and high CO Faradaic efficiency (≥90%).

Conclusions:

• Oxygen doping and asymmetric coordination effectively enhance CO₂ activation over Ca SACs.
• Ca-N₃O exhibits state-of-the-art performance for CO₂ electroreduction to CO.
• The catalyst maintains high efficiency even under diluted CO₂ conditions.