Electrochemical Conversion of CO 2 to Syngas with Controllable CO/H 2 Ratios over Co and Ni Single-Atom Catalysts.

The electrochemical CO ₂ reduction reaction (CO ₂ RR) to yield synthesis gas (syngas, CO and H ₂ ) has been considered as a promising method to realize the net reduction in CO ₂ emission. However, it is challenging to balance the CO ₂ RR activity and the CO/H ₂ ratio. To address this issue, nitrogen-doped carbon supported single-atom catalysts are designed as electrocatalysts to produce syngas from CO ₂ RR. While Co and Ni single-atom catalysts are selective in producing H ₂ and CO, respectively, electrocatalysts containing both Co and Ni show a high syngas evolution (total current >74 mA cm ^-2 ) with CO/H ₂ ratios (0.23-2.26) that are suitable for typical downstream thermochemical reactions. Density functional theory calculations provide insights into the key intermediates on Co and Ni single-atom configurations for the H ₂ and CO evolution. The results present a useful case on how non-precious transition metal species can maintain high CO ₂ RR activity with tunable CO/H ₂ ratios.
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